Download Cognitive structure and real life

Cognitive Structure
and Real Life Implementation
of Scripts in Late Adulthood
L. Godbout, PhD
M. Fiola, MA
C. M. J. Braun, PhD
S. Gagnon, PhD
ABSTRACT. Previous research has demonstrated that healthy senescent cohorts manifest marked impairment in cognitive performance, particularly on tests of executive functions. Studies directly investigating
ADL have found mild and tardive impairment in senescence, and a relation with certain executive functions, but the targeted ADL were very
simple tasks such as memorizing a telephone number or walking a few meters and have always been strictly limited to the accuracy domain–excluding any speed factor. The purpose of the present study was (1) to investigate
performance, in an experimentally controlled manner, in normal senescent
cohorts, on one of the most complex ADL (planning and preparing a
meal under time pressure), more indicative of true quality of life of seL. Godbout is affiliated with the Department of Psychology, Université du Québec à
Trois Rivières, and the Department of Psychology, Université du Québec à Montréal.
M. Fiola is affiliated with the Department of Psychology, Université du Québec à
Trois Rivières.
C. M. J. Braun is affiliated with the Department of Psychology, Université du Québec à Montréal.
S. Gagnon is affiliated with the School of Psychology, University of Ottawa.
Address correspondence to: C. M. J. Braun, PhD, Professeur Titulaire, Centre de
Neurosciences Cognitives, UQAM, C.P. 8888, Succ. Centre-Ville, Montréal, Québec,
Canada, H3C 3P8.
This research was supported by Natural Sciences and Engineering Research Grants
(Canada) to the third and fourth authors, and a Fonds de Recherche en Santé du Québec
grant to the first and third authors.
Physical & Occupational Therapy in Geriatrics, Vol. 23(1) 2004
Available online at http://www.haworthpress.com/web/POTG
 2004 by The Haworth Press, Inc. All rights reserved.
Digital Object Identifier: 10.1300/J148v23n01_03
25
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PHYSICAL & OCCUPATIONAL THERAPY IN GERIATRICS
nior citizens, and (2) to scrutinize its cognitive structure. A large battery
of tests of executive function, including a script generation task were
also administered. It was found that despite numerous marked impairments on tests of executive function, this particular ADL was not globally impaired even in advanced senescence. This finding suggests that
the combination of deep proceduralization over a lifetime and continued
daily practice suffice to maintain complex ADL, i.e., quality of life, well
into late senescence, despite important decline in cognitive resources.
[Article copies available for a fee from The Haworth Document Delivery Service: 1-800-HAWORTH. E-mail address: <[email protected]>
Website: <http://www.HaworthPress.com>  2004 by The Haworth Press, Inc.
All rights reserved.]
KEYWORDS. Aging, frontal, scripts, ADL, supervisory attentional
system, contention scheduler, central executive system, prospective
memory, planning
INTRODUCTION
Cognitive decline in late life primarily involves executive functions
(De Luca, Wood, Anderson, Buchanan, Proffitt, Mahony & Pantelis,
2003), memory (Rabbitt & Lowe, 2000) and cognitive and behavioural
slowing (Schretlen et al., 2000). Each of these three factors contributes
significant distinct variance to the decline of quality of life in the late
years.
Several executive functions depend more on frontal lobe function
than on that of other lobes (Burgess, 2000; Godefroy, Cabaret, PetitChenal, Pruvo & Rousseaux, 1999; Stuss & Alexander, 2000). Executive decline in late life is explainable by regional age-related decline of
brain function (Debettignles, Swihart, Green & Pirozzolo, 1997; Matsuda,
Ohnishi, Asada, Li, Kanetaka, Imabayashi, Tanaka & Nakano, 2003)
and anatomy (O’Sullivan, Jones, Summers, Morris, Williams & Markus,
2001) which starts before senescence to a great extent, if not primarily,
in the frontal cortex (Cowell, Turetsky, Gur & Grossman, 1994;
Schretlen et al., 2000).
Normal senescence is eventually associated with decline in self reported activities of daily living, at least in very late life (Demura et al.,
2003; Femia, Zarit & Johansson, 1997; Willis, 1996).
Some studies have observed correlations between neuropsychological tests of executive function and self ratings of ADL in the elderly
Godbout et al.
27
(Cahn-Weiner et al., 2000; Carlson, Fried, Xue, Bandeen-Roche, Zeger &
Brandt, 1999; Royall, Chiodo & Polk, 2000). It also appears that
neuropsychological tests of executive function manifest impairment in
normal aging long before any impairment of ADL can be documented
with self rating scales (Corey-Bloom, Wiederholt, Edelstein, Salmon,
Cahn & Barrett-Connor, 1996; Crawford & Channon, 2002; Grigsby,
Kaye, Baxter, Shetterly & Hamman, 1998; Steen, Sonn, Hanson &
Steen, 2001).
One must be concerned that a face-saving mechanism could cause a
bias against self-reported age-related decline in ADL, a problem which
can be overcome by direct measurement of ADL. Investigating cohorts
of normal elderly, several research groups have found that neuropsychological tests of executive function significantly correlated with functional status on the Independent Living Scales (ILS), a direct measure of
basic ADL such as simple memory items, managing money, problem
solving regarding transportation, home maintenance, and social adjustment (Cahn-Weiner, Boyle & Malloy, 2000; Carlson et al., 1999), even
when corrected for education, socioeconomic factors and disease-related processes. With these factors controlled, age itself contributes
little variance to the ILS (Bell-McGinty, Podell, Franzen, Baird & Williams, 2000). Much larger cohorts (Grigsby et al., 1998; Carlson et al.,
1999) did present a significant correlation between age and the ILS, but
the actual explained variance is unimpressive, as in the smaller scale
studies (1 to 7%).
The effect of frontal lobe dysfunction on executive function and personality, and ensuing behavioral disturbance or impairment in real life
situations in young adult patients is well established. However, very little is known about how decline of executive function in normal late life
might lead to behavioral disturbance or impairment in ADL.
Script generation is a mental representation of long action chains
leading toward a goal. Shallice (1982) first proposed a frontal lobe/basal
ganglia model of script generation in 1982. He proposed that the nonroutine, more abstract aspects of script generation are processed by a
frontal lobe module which he named the supervisory attentional system
(SAS). He also proposed that the more routine subcomponents of script
generation, individual actions, are processed automatically and procedurally by a basal ganglia module which he named the contention
scheduler (CS). Grafman (1989) has since further developed the neuropsychological articulation of script generation. He insisted on the sequencing aspect of script generation wherein time management is a
constant operant and wherein managerial knowledge units (MKUs) are
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PHYSICAL & OCCUPATIONAL THERAPY IN GERIATRICS
arranged to form chains. Rather than distinguishing the SAS from the
CS, he preferred to state that script generation has the same structure
whether the scripts be abstract or concrete, and that in both cases the
frontal lobe ought to play a critical role.
Exploration of executive components of ADL also has a relatively recent history. Frontal lobe lesions definitely impair ADL (Goel et al.,
1997; Schwartz, Reed, Montgomery, Palmer & Mayer, 1991) including
ADL formatted as routine everyday action chains which must be performed in chronological order toward a goal (Fortin, Godbout & Braun,
2003). Impairment of ADL is believed to involve primarily (or at least
importantly) executive functions of several types, including planning,
flexibility and prospective memory (Acker, 1990; Bassett & Folstein,
1991; Grafman, Sirigu, Spector & Hendler, 1993; Mazaux, Masson,
Levin, Maurette & Barat, 1997; Shallice & Burgess, 1991).
A few attempts have recently been made to operationalize script generation tasks as ADL. Schwartz and colleagues (1991; 1998) concluded
that the impairment of ADL observed in their cohorts of head trauma
patients did not resemble a frontal dysexecutive syndrome as much as a
globally limited attentional capacity. However, the ADL investigated
were very simple (e.g., making a cup of coffee).
Though normal late life is significantly associated with decline of
performance on numerous paper-pencil tests of executive function, it
remains unclear whether there is any real decline of mental or real life
implementation of lengthy routine scripts. Indeed, early senescence
does not seem to involve any decline in mental representation of routine
scripts (Godbout & Soucy, 1996; Godbout, Doucet & Fiola, 2000; Roman, Brownell, Potter & Seibold, 1987; Rosen, Caplan, Sheesley, Rodriguez & Grafman, 2003). On the other hand, when script recitation
tasks involve non-routine situations, impairment is observed in early senescence (Godbout, Cloutier, Bouchard, Braun & Gagnon, 2004).
The present investigation had four purposes concerning normal aging
in healthy, non-demented community dwellers: (1) to confirm significant weakness of executive functions as determined with neuropsychological tests in early senescence, (2) to determine whether mental
representation of routine scripts eventually breaks down in late senescence, and more importantly, the originality of this project was to (3) determine whether a highly routine, yet complex and lengthy multitask
real life activity sequence (a highly constrained and quantifiable behavioural ADL script under time pressure) is impaired in normal late life,
and (4) to determine how it is related to assessments of executive func-
Godbout et al.
29
tions and mental representations of routine scripts. The proposed methodology is identical to Fortin et al. (2003).
METHOD
Participants. Two cohorts of normal women were tested. The study
was limited to women in order to increase homogeneity of the participants’ experience with planning and preparing meals. All participants
were living autonomously and were preparing meals on a daily basis. A
young adult group comprised 23 female students aged 18 to 35. An elderly group consisted of 20 women 65 to 83 years of age. Half the participants of the last group were in early senescence (between 64 and 73
years) and will henceforth be referred to as “young old” and half were in
late senescence (between 74 and 83 years) and will henceforth be referred to as “old old.” In light of previous significant findings using the
same methods and sample sizes in frontal patients (Fortin et al., 2003;
Godbout et al., 2004), it was felt that statistical power of this experiment
would be sufficient. In the approach proposed here, the classical criterion of “large groups from which easily collectible data are obtained” is
replaced by “extremely time consuming data collection from small
small cohorts.” All participants were recruited via a local newspaper.
Exclusion criteria included substance abuse and psychiatric or neurological consultation, or any major health problem (ex: hospitalization
during the last year, cancer, diabetes, vascular, endocrinological, or
other diseases). Elderly participants were also required to be dementia
free as estimated from the Modified Mental Status Scale (Teng & Chui,
1987; limen = 80%) and the Mini Mental Status Examination (Folstein,
Folstein & McHugh, 1975; limen = 24/30). An important inclusion
criterion was that all participants be autonomous with regard to meal
preparation on a daily basis.
There was one left hander in the young adult group and one in the
young old group. All participants signed a consent form before participating (see Table 1).
Standardized tests. Tests selected for routine assessment of executive
functions covered the following four cognitive domains.
1. organization and planning: The Picture Arrangement subtest of
the WAIS-R (Wechsler, 1981) requires the subject to place in sequence, under time pressure, cards describing elements of a situation unfolding in time. The Porteus Mazes-Revised (Arthur, 1947)
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PHYSICAL & OCCUPATIONAL THERAPY IN GERIATRICS
2.
3.
4.
5.
is considered a measure of planning because the subject must analyze and memorize a trajectory through a maze before starting to
draw a pathway towards the exit.
mental flexibility and resistance to interference: The Trail Making
Test (Reitan & Wolfson, 1985) requires linking numbers on a
sheet of paper with a pencil (Part A), in order of increasing magnitude, under time pressure. The second part of the test requires
adapting to a new assignment (shifting sets) in order to link numbers to letters in alternation (Part B).
lexical access and categorization: Thurstone’s Verbal Fluency
Test (Thurstone & Thurstone, 1962), requires that the subject
state words that start with a given letter (the phonological fluency
test) or representing an animal (the semantic fluency test) without
repetition during 10 seconds–requiring rapid lexical access and
effortful attention to avoid repetitions and category errors.
selective and sustained attention: Ruff’s 2-and-7 Test (Baillargeon,
1994; Ruff & Allen, 1996), comprises a phonological attention
task, then a visuospatial attention task, then a task combining the
two previous ones. The last task is far more demanding on working memory.
mental sequencing: Luria’s Graphic Sequences (Luria, 1966) requires the subject to resist maintaining a simple behavioral set by
requiring that the subject alternate between drawing simple and
slightly more complex designs.
Script recitation task. As in Godbout and Doyon (1995), participants
were asked to enumerate out loud “10 to 20 actions, that people generally do, in proper order,” for a specific ADL. Participants were asked to
avoid idiosyncrasies and were given two examples, “getting up in the
TABLE 1. Biographic characteristics of the participants
Age (years)
Groups
Education (years) Mini Mental State
Examination
M
SD
M
SD
Modified Mental
Status Scale
M
SD
M
SD
Young adult
22.78
3.44
15.70
1.06
-
-
-
-
Young old
67.00
2.24
14.30
2.28
29.3
0.7
96.4
2.1
Old old
77.40
2.76
10.10
3.86
28.5
1.2
92.6
4.7
Note. The cut off score for the Mini Mental State Examination is 24/30, and for the
Modified Mental Status Examination, it is 80% out of 100%
Godbout et al.
31
morning” and “putting on your coat and leaving.” After repeating the
instructions correctly, they were asked to generate and recite aloud a
script representing “going to the restaurant” and another representing
“doing the groceries.” The semantic structure of the recited actions was
measured using inclusion criteria based on four types of action (% major, % minor, % trivial and % relevant intrusion) as in Godbout and
Doyon (1995) and Godbout and Bouchard (1999). To be included, an
action had to be mentioned by at least 25% of the participants of the normative study (see Godbout and Doyon, 1995). Actions that met this criterion were subsequently classified as major (mentioned by more than
65% of the participants), minor (mentioned by 45-64% of the participants) or trivial (mentioned by 25%-44% of the participants). A relevant intrusion was marked when the action did not meet the inclusion
criteria but belonged to the particular script. Sequence errors, perseverations and irrelevant intrusions were tallied as in Godbout and
Doyon (1995). Examples of sequence errors, perseverations and irrelevant intrusions in the restaurant script are (1) “paying the bill and then
eating the dessert,” (2) mentioning “paying the bill” twice, and (3) “stopping at the pharmacy,” respectively. Because of the large number of actions which must be sequenced in the subject’s mind, without any
concrete support (no test materials), beyond the limits of immediate rote
memory (which is 7 items plus or minus two), the script task is considered a planning and sequencing task which necessarily solicits working
memory (effortful action-oriented attention).
The ADL task. The assignment consisted of planning and preparing a
complete meal. It was determined that all participants had had frequent
experience with that particular ADL in real life. Participants were required to (1) prepare a menu (2) shop for groceries, and (3) prepare the
meal selected. Each of these tasks comprises a sequence which is incontrovertible. For example, doing the groceries requires taking a cart,
walking the aisles, selecting items, unloading the cart onto the counter,
and taking the bags.
The menu selection task. The participant was seated before a table
with meal suggestion cards (4 entrées, 4 main courses, 4 desserts), an
envelope containing money ($10.00) and a subset of ingredients required for each meal. The participant was required to plan a 3 course
meal within the budget allotted that could be prepared within 45-60
minutes. Only one menu was feasible, canned soup as entrée, boiled potatoes and ground beef for the main course and brownies for dessert.
The task required that the participant take cognizance of the budget, select the menu accordingly and prepare the list of missing ingredients.
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PHYSICAL & OCCUPATIONAL THERAPY IN GERIATRICS
The setting was a hospital cuisinette with two experimenters, one providing the instructions and the other handling the video camera. Participants who prepared an inappropriate menu were requested, afterwards,
to prepare the soup-beef/potatoes-brownie menu so as to create a more
standard context for the subsequent task.
The grocery shopping task. Once the menu was planned, the participant was required to go to the grocery and purchase the missing ingredients, having been instructed to select the smallest quantities of the
essential ingredients only, and to stay within the budget. The experimenters accompanied the participant and took note of the behavior.
The meal preparation task. Once back at the cuisinette, the participant was required to prepare the meal as if for a guest arriving in an
hour–including setting the table for two. To respect this constraint, the
participant had to understand that the dessert had to be prepared first (30
minutes preparation time). Participants were filmed and the experimenters limited their interactions with the participant to a strict minimum.
The neuropsychological tests, script recitation task and ADL were
completed in counterbalanced order.
Scoring System of the ADL Tasks
ADL tasks were scored in two different ways. In a first step, the level
of success in completing the tasks was assessed. Errors belonging to this
category are severe enough to prohibit appropriate completion of the
task. In a second step, all action errors were examined in detail.
Inability to achieve the goal. When errors of this type are made,
chances that the task will be completed successfully decrease. The nature of those errors vary according to the ADL task. For instance, in the
menu selection two errors could be made: selecting the wrong menu
(based on the criteria already mentioned) or the wrong ingredients. For
the grocery shopping, the following errors could occur: purchasing the
wrong items or the wrong quantities, not limiting their purchases to the
given budget or using extra money to buy food items. Finally, for the
meal preparation, four type of errors were also of interest: not following
the recipe, not completing each course of the meal successfully, not preparing the meal within the allotted time, and not finishing the courses simultaneously (not cold or overcooked). For each ADL task, the previous
errors were summed up.
Action errors. Action errors are similar to those tallied in the script
recitation task. For the three ADL tasks, sequence, perseveration, intrusion and omission errors were compiled. In some cases, those errors
Godbout et al.
33
might significantly influence the outcome of the ADL task (e.g., sequence, perseveration, intrusions errors might increase time duration
and decrease the quality of the outcome).
Other types of error were specific to the meal preparation task. This
ADL task is the only one that comprises subscripts corresponding to
each element of the meal (cooking the soup, the meat, the potatoes and
preparing and baking the dessert). One error was associated with strategic planning and anticipation and was termed a first action error. The
second was termed an end point timing error. Appropriate planning of
the meal requires that the participant start by preparing the dessert first
(first action error). It had to be prepared first because the recipe specified that it took far longer to cook than any other course. Participants
also had to anticipate when each course would be ready in order to make
sure that the four courses arrive at completion more or less simultaneously (end point timing error). In addition to anticipation, self-correction and time estimation are most likely involved in assuring that the
meal is ready on time (Fortin et al., 2003). For this last variable, more
than 12 minutes between two courses was the criterion for desynchrony
of courses, based on the fact that none of the controls of the present study
or of the 10 frontally lesioned patients (Godbout, Cloutier, Bouchard,
Braun & Gagnon, 2004) or 10 controls of another study (Fortin et al.,
2003) had surpassed 11 minutes. These latter functions are increasingly
being recognized as none other than prospective memory (Wilkins &
Baddeley, 1978). Indeed, when a lot of interference occurs during a substantial time interval, “planning” becomes “prospective memory”: the
ability to remember to do something in the future.
Alternation behavior. Alternation behavior was also examined in the
meal preparation task. When cooking a meal it is normal to oversee the
various components, in alternation. The cook can lower the heat if a
course seems to be cooking too fast or raise the heat if a course is getting
behind. This requires abandoning a course (ex: cooking the potatoes)
for another (ex: cooking the beef) and vice versa and back and forth. Of
course, alternation can be insufficient or it can be excessive. At any rate,
this behavior was tallied for the meal preparation task only.
Time-on-task. Finally, for all ADL tasks, one last variable was considered. Time on task was noted in minutes. This measure varied considerably and was thus transformed [log10(time required + 1)].
Macrostructure and microstructure of the ADL. In such a complex
multitask ADL, we have proposed (Fortin et al., 2003; Godbout et al.,
2004) that mental operations can be conceptualized and operationalized
in terms of a macrostructure and a microstructure. The macrostructure
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PHYSICAL & OCCUPATIONAL THERAPY IN GERIATRICS
is the representation and implementation of the script as a whole (i.e.,
the actual plan towards a goal). This is a relatively abstract level of representation, germaine to the SAS (Shallice, 1988). The microstructure is
the representation of the highly routine (overlearned and relatively
short) sub-sequences of the script in which individual actions are
termed “nodes” by Grafman (1989) (e.g., greasing the pan, putting the
ground beef in the pan, turning off the element). This is a relatively concrete level of representation, which relates to the CS (see Fortin et al.,
2003). These macro and microstructures cannot be drawn quantitatively
from recited scripts, or even from the menu preparation or grocery
shopping tasks. We believe this is why previous attempts to dissociate
the CS from the SAS, with script recitation tasks, have failed. Only the
meal preparation task lent itself to an operationalization of macrostructure/microstructure construct.
We propose that the script’s macrostructure, in the cooking phase, is
reflected in the first node and the ending. There is a deficit of macrostructure if the participant does not prepare the dessert first (first action
error) and if the courses do not arrive on time or in fast enough sequence
(end point timing error). The former represents a deficit of anticipation
and strategic planning and the second represents an impairment of planning, self-correction and time estimation (Fortin et al., 2003). These latter functions are increasingly being recognized as none other than
prospective memory (Wilkins & Baddeley, 1978). The dessert had to be
prepared first because the recipe specified that it took far longer to cook
than any other course. Errors of the microstructure included sequencing, perseverative, intrusive and omission errors. These errors do not
necessarily result from an inability to abstract the script as a whole.
They reflect more concrete and simple cognitive operations.
The scoring system for our ADL has been developed in the course of
several previous research projects on normal aging (Godbout, Doucet &
Fiola, 2000; Godbout & Soucy, 1996) and frontally lesioned patients
(Fortin et al., 2003; Godbout et al., 2004) as well as normal control
groups in each of these studies. Scoring was done from the videotapes
and notes by two independent raters. In the results section which follows, the alpha criterion is set at .05, and all inference tests are twotailed.
Self-rating of competence on ADL. Finally, the Cognitive Failure
Questionnaire (CFQ) was used to evaluate ADL (Broadbent et al.,
1982). The CFQ is a self-rating questionnaire which measures frequencies of failures of behavior in daily life.
Godbout et al.
35
RESULTS
Matching of the Experimental and Control Groups
An ANOVA revealed a significant difference between groups in education (F(2,40) = 19.4, p < .001), a nearly inevitable effect of generations.
The Tukey post hoc test determined that only the old old group (M =
10.1 years, SD = 3.9) differed significantly from the young adult (M =
15.7 years, SD = 1.1) and young old (M = 14.3 years, SD = 2.3) groups
(see Table 1).
Neuropsychological Tests
For each test measure, the 23 young adult and 20 elderly participants
were compared with ANOVA. As expected, most of the measures of
executive function (14/17) yielded significant group effects compatible
with an age-related decline in performance (see Table 2).
We then proceeded to subdivide the elderly group into young old
(N = 10) and old old (N = 10). For each test measure, the three groups
were compared with ANOVA followed by the Tukey post hoc test for
determination of simple effects. Exactly the same measures of executive function yielded significant group effects as previously, demonstrating an age-related decline in performance. In addition, significant
weaknesses of the old old group relative to the young old group were
observed on Trails B (time), Trails B minus A (time), Luria’s sequences
B, and Semantic fluency. Though most neuropsychological measures of
the present investigation were significantly correlated with education,
the word fluency and Trails B minus A measures were not. This suggests that the effects reported above concerning these two particular
measures can confidently be attributed to age, not education. Furthermore, statistical correction for education via ANCOVA did not bring
any of the significant effects under the alpha criterion. These results
confirm the “classical” cognitive impairment profile reviewed in the
introduction.
The Script Recitation Task
Total actions. The total number of actions generated did not differ as
a function of the two age groups (F(2, 40) = 1.1). This result allowed us
to proceed with the analysis of the semantic structure and pattern of
errors.
36
10.83 (2.61)
1.91 (2.21)
25.39 (7.67)
52.04 (16.75)
26.65 (17.25)
45.48 (17.54)
.22 (.52)
22.83 (8.62)
.22 (.74)
39.70 (10.24)
.39 (.50)
1.26 (1.18)
44.57 (9.32)
.96 (1.15)
.52 (1.56)
94.04 (15.18)
94.35 (13.61)
6.30 (1.68)
4.60 (2.62)
52.90 (20.09)
91.50 (20.75)
38.60 (20.21)
72.10 (16.40)
.60 (.66)
46.20 (12.77)
.20 (.40)
34.80 (9.31)
1.20 (1.94)
2.70 (2.15)
39.70 (7.50)
.90 (.70)
.20 (.60)
60.50 (17.63)
58.40 (15.12)
Group
Young old
n = 10
5.40 (1.50)
5.60 (1.69)
50.90 (7.18)
170.90 (103.67)
120.00 (103.28)
76.70 (19.84)
1.40 (1.28)
58.60 (14.29)
.20 (.40)
29.00 (6.13)
1.40 (1.56)
2.00 (1.48)
30.70 (7.34)
.70 (1.19)
.50 (.81)
50.80 (9.84)
47.60 (13.60)
Old old
n = 10
26.92
11.11
25.79
16.71
10.70
13.52
7.30
38.17
.00
4.61
2.68
3.07
8.93
.19
.24
37.17
48.43
F
.0001a, b
.0001a, b
.0001a, b
.0001b, c
.0012b, c
.0001a,b
.002b
.0001a,b,c
.9957
.0158b
.0810
.0574
.0006b, c
.8255
.7879
.0001a, b
.0001a, b
p
Note. a = significant difference between the young adult and young old groups, b = significant difference between the young adult and old old groups, c = significant
difference between the young old and old old groups.
Tests
Picture Arrangement (WAIS)–Scale score performance
Porteus Mazes–Trials required to complete correctly
Trail Making A–Seconds required to complete
Trail Making B–Seconds required to complete
Trail Making (B minus A)–Seconds required to complete
Luria’s Series A–Seconds required to complete
Luria’s Series A–Perseverative errors
Luria’s Series B–Seconds required to complete
Luria’s Series B–Perseverative errors
Verbal Fluency–Number of words stated in 10 seconds
Verbal Fluency–Perseverative errors
Verbal Fluency–Rule breaking errors
Semantic Fluency–Number of words stated in 10 seconds
Semantic Fluency–Perseverative errors
Semantic fluency–Rule breaking errors
Ruff’s 2-7 Single Task–Items correct
Ruff’s 2-7 Dual Task–Items correct
Young adult
n = 23
TABLE 2. Means (and standard deviations) on standardized tests of executive function and tests of the inference of
group differences
Godbout et al.
37
Semantic content. A 2 ⫻ 4 repeated measures ANOVA was calculated on responses within each of four semantic categories as a function
of the 2 age groups. The semantic categories were major, minor, trivial
or relevant intrusion. Though there was a significant effect of semantic
category (F(1,41) = 14.5, p < .0001), none of the effects involving age
reached significance. Tukey post hoc tests revealed that relevant intrusions were significantly more frequent than each of the three other semantic categories. When the three age groups were compared, these
ANOVAs yielded the same results, confirming the results reported by
Rosen et al. (2002).
Error analysis. Three types of errors were scored, namely sequence
errors, perseverations and irrelevant intrusions. Because of low rates,
non-parametric analyses (Fisher exact probability test) were performed
on cases dichotomized as having committed or not each type of error.
The two group comparison did not reach significance for sequence errors (4/23, 9/20), perseverative errors (1/23, 5/20) or irrelevant intrusions
(0/23, 3/20).
With a three group model, there was a significant deterioration with
age for sequence errors and irrelevant intrusion errors, but not perseverative errors. See Table 3.
None of the script generation task measures were significantly correlated with education, indicating that education was not a confounding
factor of age effects.
TABLE 3. Percentages of cases presenting various types of errors on the script
generation task and probabilities of significant effects based on the Fisher
Exact Test
Types of errors
Young
n = 23
Group
Young old
n = 10
Old old
n = 10
17%
30%
60%
.049 b
Perseveration
4%
20%
30%
.12
Irrelevant intrusion
0%
0%
30%
.005 b
Sequence error
p
Note. a = significant difference between the young adult and young old groups,
b = significant difference between the young adult and old old groups,
c = significant difference between the young old and old old groups.
38
PHYSICAL & OCCUPATIONAL THERAPY IN GERIATRICS
The Activity of Daily Living (ADL)
Inter-judge agreement for ratings of the ADL were at least 98% for
the young adult group data and 97% for the senescent groups, with respect to all ratings except alternation (80%).
Inability to achieve the goal. The rates for this type of error were too
low to support parametric analysis, so for this error measure cases were
dichotomized as presenting one or more errors versus none. Fisher exact probability tests revealed no group differences in preparation of the
menu (10/23, 3/20), in grocery shopping (8/23, 5/20) or in meal preparation (9/23, 6/10). Nor were there group effects in a three group model
(10/23, 2/10, 1/10), (8/23, 4/10, 1/10) (9/23, 3/10, 3/10).
Time-on-task. An ANOVA (two groups) revealed a significant main
effect of age for the grocery shopping condition (t(1,41) = 4.6, p < .0001)
and for the meal preparation condition (t(1,41) = 3.9, p < .0005) but not
for the menu preparation condition. The younger subjects performed
better.
An ANOVA designed for the same inference tests with three groups
instead of two revealed a significant effect of age for the menu preparation condition (F(2,40) = 6.7, p < .01), for the grocery shopping condition
(F(2,340) = 13.7, p < .001) and for the meal preparation condition
(F(2,40) = 6.5, p < .01). In all three cases, post hoc tests revealed that the
old old group was significantly slower than the two other groups.
Alternation behavior. Alternation behavior was analyzed with ANOVA.
In a two group model, the young adult group presented more alternation
than the elderly group (F(1,40) = 14.4, p < .001). In the three group
model, there was significantly more alternation behavior (F(2,40) = 6.8,
p < .01) in the young adult group (M = 53, SD = 18.2) than in the young
old (M = 36, SD = 10.8) or old old groups (M = 37, SD = 9.3), and the
latter two groups did not differ from each other.
Microstructure. In the two group model, there was no main effect of
age in ANOVA with regard to perseverative errors. However, there
were more sequencing errors and irrelevant intrusions in the elderly
group but fewer omissions. The results were similar in the three group
model (see Table 4).
Macrostructure. Errors of the macrostructure consisted of two eventualities: not starting with the dessert in the meal preparation task and
overpassing a synchronization criterion (12 minutes per course) in serving the meal. Taken separately, these two measures did not differ significantly as a function of group as determined by ANOVA in either the
two or three group models. In the three group model, if summed, these
Godbout et al.
39
TABLE 4. Means and standard deviations of four types of errors relevant to the
microstructure on the activity of daily living (ADL) task and tests of the inference of group differences
Error type
Group
F
p
Young adult
Young old
Old old
1.35 (1.53)
.70 (.78)
1.40 (1.36)
.90
.4155
.13 (.34)
1.00 (1.00)
2.10 (3.27)
4.62
.0157b
Sequence
2.39 (1.31)
3.30 (1.68)
3.60 (2.11)
2.26
.1173
Omission
1.04 (1.26)
2.70 (1.62)
2.00 (1.26)
5.38
.0086a
Perseveration
Irrelevant intrusion
Note. a = significant difference between the young adult and young old groups,
b = significant difference between the young adult and old old groups,
c = significant difference between the young old and old old groups.
two error types yielded a significant difference, but only between the
young adult and old old groups. See Table 5.
None of the ADL task measures were significantly correlated with
education, indicating that education was not a confounding factor of age
effects.
Regarding the question of relative magnitude of the effects observed in neuropsychological test measures and ADL performance
task measures (continuous variables only), we converted the F values
to Pearson correlations using Guilford’s (1965) formula; we also calculated intercorrelations of all these measures, and then applied Guilford’s
(1965) inference test of a difference between correlation coefficients.
Script generation tasks measures could not be thus treated as none
were continuous. A first test of interest, serving to determine whether
the neuropsychological tests are more sensitive than the ADL tasks,
was to compare Ruff’s Dual Task measure with the omission error
score on the ADL task. Both of these were the most sensitive to age in
their respective domain (neuropsychological tests versus ADL tasks).
The difference was not statistically significant, indicating that ADL
tasks are just as sensitive to the effect of aging as the most sensitive
neuropsychological tests of the present investigation. Likewise, the
“overall planning” ADL score (i.e., the macrostructure) did not differ
significantly from Ruff’s Dual Task in its ability to distinguish the age
groups.
40
PHYSICAL & OCCUPATIONAL THERAPY IN GERIATRICS
TABLE 5. Macrostructure: Means and standard deviations of two types of “errors” on the activity of daily living (ADL) task and tests of the inference of group
differences
Error type
Young adult
Group
Young old
Old old
F
p
Starting point error
.57 (.84)
.60 (.92)
1.50 (1.12)
3.59
.0368
End point time
interval (seconds
over the time limit)
448 (406)
467 (378)
703 (499)
1.17
.3217
Overall planning
.78 (.90)
.80 (1.25)
2.10 (1.30)
5.24
.0095b, c
Note. a = significant difference between the young adult and young old groups,
b = significant difference between the young adult and old old groups,
c = significant difference between the young old and old old groups.
Planning represents the sum of starting point errors and of incidence of surpassing the 12 minute
synchrony criterion for serving the courses warm.
Prediction of performance on ADL with paper-pencil tasks and tests.
ADL tasks such as the ones implemented here are far too time consuming
and expensive to be of much use in a typical professional neuropsychological evaluation (though that might not be the case for occupational
therapy). Yet, estimation of ADL is the prime concern of most professional neuropsychological evaluations in the elderly population. After
all, the purpose of the evaluation of healthy elderly is usually not so
much to plan remediation, but to recommend a life course (autonomous,
semi-dependent, fully dependent). It is, thus, of interest to determine
whether there are any good inexpensive predictors of ADL. The first
such plausible predictor that comes to mind is the Cognitive Failures
Questionnaire. This questionnaire did not distinguish the age groups
nor did it correlate significantly with any of the ADL measures.
On the other hand, virtually all the neuropsychological test measures
significantly predicted one or several performance scores on the ADL
tasks. The best such predictors, Trails-B and Ruff’s Dual Task, significantly predicted most ADL performance measures. See Table 6 for examples. These results, even the specific pattern of results, corroborates
the relevant previous research cited in the introduction.
The script generation task did not yield scores with distributions sufficiently continuous to justify correlational analysis. However, the sum
of all error types (omissions, irrelevant intrusions, perseverations, sequence errors) was sufficiently continuous for this purpose. This index
Godbout et al.
41
TABLE 6. Prediction of performance on the meal preparation ADL by the Cognitive Failures Questionnaire, a selection of neuropsychological tests and the
composite error score on the script generation task (Pearson product-moment
correlations and probability levels)
Inability
to achieve
the goal
CFQ
Trails-B
seconds
Time on
task
Alternation Requests
behavior for repetition
of the
instructions
.07 (.629) ⫺.10 (0.518) .06 (.687)
.20 (.197)
.30 (.049) ⫺.29 (.058)
Ruff’s Dual ⫺.09 (.551) ⫺.23 (.137)
Task
Script
generation
error score
composite
.45 (.002)
.35 (.019)
Microstructure
Macrostructure
.06 (.679) ⫺.01 (.938) ⫺.01 (.941)
.68 (.0001) .55 (.0001) .45 (.003)
.53 (.0003) ⫺.56 (.0001) ⫺.56 (.0001) ⫺.30 (.050)
.69 (.0001)
.69 (.0001)
.50 (.0006)
.26 (.086)
was a remarkably good predictor of ADL (see Table 6 for examples),
suggesting that a brief script generation task, scored in this manner
might be a new and useful component of a gerontological neuropsychological test battery.
DISCUSSION
As expected, early senescence was characterized by significant deterioration on most of our standardized tests of executive function, and
the decline was significantly exacerbated by late senescence, a finding
unexplainable by differing education levels of the age groups. Of
course, some tests of executive function are more sensitive to normal
aging than others. The set of tests of executive function of the present
investigation included indexes of planning and anticipation (Picture Arrangement and Porteus Mazes), of visuomotor speed and control (Trail
Making Test, Luria’s sequences), of verbal fluency (Phonological fluency, semantic fluency), and of sustained attention (our adaptation of
the Ruff 2-7 task, visual modality only, visual and auditory dual task
version). All of these functions are known to decline in normal aging:
[planning and anticipation: Vakil & Agmon-Ashkenazi, 1997, visuo-
42
PHYSICAL & OCCUPATIONAL THERAPY IN GERIATRICS
motor speed: Rabbitt, 1996, verbal fluency: Mittenberg, Seidenberg,
O’Leary & DiGiulio, 1989, Thuillard & Assal, 1991, sustained attention: Craik & Byrd, 1982; Plude & Hoyer, 1986]. In the present investigation, all these categories manifested decline in early senescence
except verbal fluency–which manifested significant decline only in late
senescence. The relative robustness (resistance to aging), within the domain of executive functions, of verbal fluency, has been previously observed (Daigneault, Braun & Whitaker, 1991). This can easily be
explained by its “vocabulary” component which is indexed as a well established “hold” measure of the WAIS tests, i.e., vocabulary has long
been known to resist aging quite well (Wechsler, 1981).
It is already known that mental genesis of routine scripts (indexed by
recitation), such as those of the present study, is not impaired by early
senescence (Godbout & Soucy, 1996; Light & Anderson, 1983; Roman,
Brownell, Potter & Seibold, 1987). This was confirmed here. All age
groups were comparable in total number of actions and semantic structure. In short, at all ages, participants went about the task with quite similar strategies and cognitive representations. However, there was a
modestly significant decline in ability, as indexed by sequence errors
(an established index of frontal lobe function), (Fortin et al., 2003;
Godbout & Doyon, 1995), by late senescence. Senescent participants
also tend to be generally more idiosyncratic, self-centered, in their
response style (Roman et al., 1987) and we believe this may be the principal explanation of the observed significantly increasing rate of irrelevant intrusions in late senescence. This confirms there exists a certain
robustness of representation of routine scripts in normal aging, but at
the same time specifies that there is a limit to this robustness.
With regard to real life activities of daily living (ADL), this investigation presents the advantage and innovation of an exhaustive quantitative scoring grid of a very complex set of sequential activities under
demanding time constraints. Though routine, these activities could well
be the most complex and demanding in the everyday lives of senescent
retirees. The outcome of this particular component of the present investigation is basically a demonstration of a remarkable robustness of complex routine ADL in normal aging, including late into senescence.
Though the senescent participants were significantly slow (as indexed
by time-on-task which surpassed the allotted limit on average) and significantly idiosyncratic (as indexed by irrelevant intrusions) they were
quite able to carry out the task, to plan and deliver a three course meal.
There are three arguments supporting the view that experience with
these ADL protects them from decline in late life: (1) healthy elderly
Godbout et al.
43
women continue to plan and prepare meals on a daily basis in high proportion (Moane, 1993), (2) significantly greater rates of omission errors
and of alternation behavior of the young adult group in this study suggest that the senescent participants had a stronger procedural memory
for this type of task, and (3) script recitation is not impaired in early senescence when the content of the recitation is routine (overlearned), but
the same task reveals impairment in early senescence when the script
must be recited in reverse order (a condition adding novelty, i.e., load,
to working memory) or when a novel script must be created to deal with
a novel goal (Bourassa, 2000; Bourassa & Godbout, 1996; Godbout &
Bouchard, 1997).
Nevertheless, it seems that frontal lobe-based executive function decline must inevitably impose limits on complex routine ADL requiring
long sequences of actions under time constraints. Indeed, though there
was a deficit of microstructure in senescence, this can best be explained
as a manifestation of the previously described idiosyncratic style of senescence (Roman et al., 1987) rather than as an impairment per se. Our
senescent participants made remarks about the meal not having to do
with their own food preferences and intolerances and had difficulty
de-centering their attitude from their own gastronomic style to this “generic” task which was not adapted to their specific lifestyle. For example, one old old participant declared that she needed more fruits and
vegetables and proceeded, inefficiently, down those aisles in the grocery
store.
In addition, there was a modestly significant decline in the macrostructure by late senescence. The old old participants were slightly impaired in their ability to counter-intuitively sequence the cooking agenda
and to adjust pro-actively all the ongoing subscripts, for optimal end
point synchrony of the ensemble of the courses. In short, the old old participants of this investigation seemed to be faced with mild difficulties
in strategic planning and in prospective memory. This suggests that a
frontal-executive impairment was emerging which had become too profound to be compensated by everyday learning. We propose that strategic
planning (see the introduction) and prospective memory are important
components of complex ADL and both of these draw heavily upon
working memory.
Prospective memory consists of remembering, in the future, to execute a specific action. Prospective memory has been demonstrated to be
frontal lobe based (Cockburn, 1995; Okuda, Fujii, Yamadori, Kawashima,
Tsukiura & Fukatsu, 1998), to relate to several higher order executive
functions (Bisiacchi, 1996; McDaniel, Glisky, Guynn & Routhieux,
44
PHYSICAL & OCCUPATIONAL THERAPY IN GERIATRICS
1999; Shallice & Burgess, 1991; Shapiro, Shapiro, Russell & Alper,
1998) and to be very important in ADL (Marsh, Hicks & Landau, 1998;
McDaniel & Einstein, 1992; Van den Broek, Downes, Johnson, Dayus, &
Hilton, 2000). Prospective memory is known to decline in normal aging
(Daum, Graber, Schugens & Mayes, 1996; Maylor, 1995; Rendell &
Thomson, 1999). It is not yet known which sub-areas of the frontal lobe
might contribute most to prospective memory. Burgess and colleagues
(2000) recently reported a major investigation of effects of focal lesions
on a multitask laboratory activity. They found that lesions to the left
posterior cingulate and forceps major regions gave deficits on “task
learning and remembering, plan-following and remembering one’s actions,” but not “planning.” Remembering task contingencies after a delay was also affected by lesions in the region of the left anterior
cingulate, and rule-breaking and failures of task switching were additionally found in people with lesions affecting the medial and more polar aspects of Brodmann’s areas 8, 9 and especially 10. Planning deficits
were associated with lesions to the right dorsolateral prefrontal cortex.
They distinguished “planning” from “prospective memory,” and considered that the brain basis of each is distinct.
Working memory has been identified as an important component of
ADL (Carlson, Fried, Xue, Bandeen-Roche, Zeger & Brandt, 1999).
One particularly elegant conceptualization of working memory is the
central executive system (CES). The CES is a high order cognitive frontal lobe module which manages multiple complex mental operations
under time pressure, and which is subserved by hemispherically specialized slave systems, namely a left hemisphere phonological loop system and a right hemisphere visuospatial scratchpad (Baddeley, 1986;
Baddeley & Della Sala, 1996; D’Esposito, Detre, Alsop, Shin, Atlas &
Grossman, 1995; Smith & Jonides, 1997). Tasks purported to solicit
one or the other slave system are considered CES tasks when they are
required to be carried out simultaneously under time pressure (dual task
paradigm) (Baddeley & Della Sala, 1996; Baddeley, Della Sala, Papagno &
Spinnler, 1997; Della Sala, Baddeley, Papagno & Spinnler, 1995). The
CES has been demonstrated to lodge principally in the frontal lobes
(Baddeley et al., 1997; Collette et al., 1999). The CES manifests marked
decline in normal aging (Spinnler, Della Sala, Bandera & Baddeley,
1988). Unfortunately, we have not been able to locate any reports of research on the link between the CES and ADL in brain damaged patients,
but the idea has indeed been articulated (Stablum, Umilta, Mogentale,
Carlan & Guerrini, 2000). The findings of the present research indirectly support the notion of a decline of the CES in normal aging. In par-
Godbout et al.
45
ticular, the meal preparation task can be construed to resemble a CES
task: it involves multitasking under time pressure. Recall that the old
old group was significantly slower than the other two groups on the
ADL task.
In short, there is a frontal-executive decline in normal aging, but
script recitation tasks for routine activities and routine ADL under-represent this frontal-executive impairment, even though they draw heavily
upon it, probably because complex routine mental representations and
everyday activities continue to be learned and consolidated (a sort of
proceduralization and automatisation, an increasing easiness or unhesitatingness) even into senescence. Eventually, however, the frontal-executive deterioration of senescence attacks the least routine and least
automatized aspects of such tasks and activities: they make their execution less strategic, less adaptable, on the one hand, and they make it difficult for the senescent participants to handle complex multitasking
under time constraint, i.e., in working memory.
CONCLUSION
Frontal lobe deterioration is an important aspect of normal aging; it is
reflected in neuropsychological tests of executive function, especially
those most demanding–working memory. Activities of daily living
(even complex ones), however, are protected from this decline by deep
proceduralization and daily practice, but eventually cannot escape being
compromised by it.
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