Download Effects of ageing on gastrointestinal motor function

J. L. Madsen, J. Graff
References
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Received 24 September 2002; accepted in revised form 12 September
2003
Age and Ageing Vol. 33 No. 2  British Geriatrics Society 2004; all rights reserved
Effects of ageing on gastrointestinal
motor function
JAN L. MADSEN, JESPER GRAFF
Department of Clinical Physiology and Nuclear Medicine 239, Hvidovre Hospital, University Hospital of Copenhagen,
Kettegård Allé 30, DK-2650 Hvidovre, Copenhagen, Denmark
Address correspondence to: J. L. Madsen. Fax: (+45) 3622 3750. Email: [email protected]
Abstract
Background: existing data on the effect of ageing on gastrointestinal motility are few. In this study, we assessed the propulsive
effect of all main segments of the gastrointestinal tract in a group of healthy older people.
Methods: 16 healthy volunteers (eight women, eight men) of mean age 81 years (range 74–85 years) participated in the
study. Gastric emptying and small intestinal and colonic transit rates were determined by gamma camera technique. The
154
Gastrointestinal motor function
technique was also used to measure the postprandial frequency of antral contractions. Furthermore, we assessed the effects
of gender, body mass index and smoking on the motility variables. The results were compared with data from 16 healthy
individuals (eight women, eight men) of mean age 24 years (range 20–30 years).
Results: advanced age did not inXuence gastric emptying or small intestinal transit rate. Older individuals had a slower
colonic transit than young individuals (P = 0.0008). No difference was found in postprandial frequency of antral contractions
between older and young subjects. None of the motility variables was affected by gender or body mass index. Smokers had
a faster colonic transit than non-smokers (P = 0.0022).
Conclusion: normal ageing seems to reduce the propulsive capacity of the colon, whereas gastric and small intestinal motility is
not affected.
Keywords: ageing effects, gastric emptying, small intestinal transit, colonic transit, postprandial frequency of antral contractions,
gastrointestinal transit time, gastrointestinal motor function, elderly
Introduction
So far, relatively little work has been done to describe the
gastrointestinal changes associated with normal ageing and
in many instances normal data on which to base clinical
comparisons are not available [1]. Thus, only a few studies
have been published that describe normal colonic motility
among older subjects, and similar limitations apply to gastric
and small intestinal motor function. The studies that have been
done commonly reveal conXicting results due to differences
in the used methodology. In addition, the increasing prevalence
of coexisting diseases and medications with age make studies
on healthy individuals beyond the seventh decade of life
difWcult. However, owing to a large functional reserve capacity
of the gastrointestinal tract ageing seems to have little direct
clinical effect on most gastrointestinal functions [2].
Traditional techniques for studying gastrointestinal motor
function are inconvenient, invasive, or imprecise. Radiological
procedures with barium sulphate suspensions only provide
qualitative results. Intubative techniques are inconvenient,
and intubation itself may interfere with normal gastrointestinal
motility. The hydrogen breath test gives an index of the time
taken for the head of the fermentative substrate to pass from
the mouth to the caecum. However, the test does not permit
the obtaining of a separate small bowel transit time, and small
intestinal bacterial overgrowth may inXuence the results.
Ultrasonography and MRI can only be used to evaluate gastric
motor function. In recent years, repetitive gamma camera
imaging after oral intake of physiological radiolabelled markers
has proven useful for the quantitative assessment of the
motor function of all main segments of the gastrointestinal
tract [3, 4]. In the present study, therefore, scintigraphy was
used to assess gastric emptying rate and small bowel and
colonic transit rate among healthy older volunteers. Furthermore, we evaluated the separate effects of gender, body mass
index and smoking on these motility variables.
Methods
Subjects
Sixteen healthy volunteers (eight women, eight men) of mean
age 81 years (range 74–85 years) and mean body mass index
25.0kg/m2 (range 21.6–29.7kg/m2) participated in the study.
Two were smokers. Results were compared with data from
16 healthy volunteers (eight men, eight women) of mean age
24 years (range 20–30 years) and mean body mass index
22.4 kg/m2 (range 18.9–26.5 kg/m2) [5]. Five were smokers.
None of the participants had antecedents of abdominal surgery
except for appendectomy, abuse of alcohol, or treatment
with drugs including laxatives that were known to interfere
with normal gastrointestinal motility. None of the volunteers
had symptoms referable to gastrointestinal disease or reported
constipation or obstructed defaecation during the investigations. All subjects were recruited by advertisement within the
community. Written informed consent was obtained from
all volunteers and the local medical ethics committee
approved the study protocol.
Measurements
Gastrointestinal transit was measured with gamma camera
technique [5, 6]. Studies began in the morning after an overnight fast. In 10 minutes, each subject ingested a 1600-kJ
mixed liquid and solid meal (80 g of bread, 120 g of egg
omelette, 200 g of water) containing radiolabelled markers.
As a liquid marker 4 MBq of 111In diethylenetriamine pentaacetic acid (111In-DTPA) was added to the water, and as
a solid marker 20 MBq of 99m Tc stannous colloid was added
to the egg omelette. Anterior and posterior images were
acquired with the subject in the upright position. Imaging
was repeated at 30-minute intervals until no radioactivity
could be detected in the small intestine. If the examinations
had not already been Wnalized, the subjects had a further
meal at 13.00 h and 17.00 h. For the following days, imaging
was repeated at 24-hour intervals until all radioactivity had
cleared from the colon. All volunteers kept their usual diet
and smoking habits during the whole study period. Postprandial frequency of antral contractions was assessed from
anterior dynamic images of 1 sec each, which were acquired
for 5 minutes at 60 minutes after the radiolabelled meal [7].
Data analysis
Regions of interest for integration of radioactivity were
delineated manually around the stomach and the colon on each
image. To minimise errors in the interpretation, sequential
images were displayed forwards and backwards in time, showing the movement of the markers. Counts were corrected for
down scatter, gamma ray attenuation and physical decay. The
155
J. L. Madsen, J. Graff
percentage of marker in the small intestine was estimated
from the percentage of marker in the stomach and in the
colon. Due to the relatively quick input of radiolabelled marker
into the stomach and the colon, the directly obtained timeactivity curves reXected gastric and colonic transit quite well.
By contrast, the relatively slow process of gastric emptying
had considerable inXuence on the directly obtained small
intestinal time-activity curves. Therefore, the mathematical
principle known as deconvolution analysis was used to
construct the time-activity curves to be expected from an
instantaneous input of all radioactive marker into the small
intestine [6]. For statistical comparisons, the information
given by each time-activity curve was condensed into one
single variable, the mean transit time, by dividing the area
beneath the curve with its initial, maximum, value. This variable, which expresses the mean time for all radioactive material
to enter and leave the corresponding gastrointestinal segment,
does not presuppose particular emptying or transit kinetics [6].
Due to the short physical half-life of 99mTc colonic mean transit times were only obtained for 111In-labelled liquid marker.
The method used to process the dynamic images has been
described elsewhere [5]. For precise presentation of the antrum,
each set of dynamic images was at Wrst reframed into a single
image, and a box region of interest was localized over the
distal antrum close to the pylorus. Then the position of the
geometric centre of radioactivity was determined on each
1-second image. On the assumption that the horizontal
oscillations of the geometric centre of radioactivity in the
region of interest reXected the contractile activity of the antrum,
fast Fourier transform analysis was used to Wnd the frequency
of these contractions.
Statistical analysis
Multiple regression analysis was used to evaluate the effects
of age, gender, body mass index and smoking on the mean
transit times. The level of signiWcance was 0.05.
Results
Results of gastrointestinal motility assessments are shown in
Figures 1–3 and in Table 1. Results of the multiple regression
analysis appear in Table 2 . Advanced age did not inXuence
gastric emptying or small intestinal transit rate. Older
individuals had a slower colonic transit than young individuals
(P=0.0008). No difference was found in postprandial frequency
of antral contractions between older and young subjects. None
of the motility variables was affected by gender or body
mass index. Smokers had a faster colonic transit than nonsmokers [30 hours (14–44 hours) versus 59 hours (27–98 hours),
P = 0.0022].
Discussion
There is relatively little information about the effects of ageing
on gastrointestinal motor function in humans, although this is
likely to be fundamental to an understanding of gastrointestinal symptoms, appetite regulation, and absorption of both
nutrients and oral drugs. A number of studies have been performed in subjects who were hospitalised or taking drugs that
might affect gastrointestinal function [8, 9]. The extrapolation
156
Figure 1. Gastric emptying of liquid and solid marker in
16 older and 16 young volunteers. Horizontal bars indicate
mean values.
of the results of such studies to healthy older populations is
dubious. However, there seems to be an increase in gastrointestinal disorders of function and motility with ageing. The
most frequent gastrointestinal motor problems encountered
by the gastroenterologist in the older patient include
dysphagia, dyspepsia, anorexia and constipation [2]. In some
of the patients, delayed gastric emptying and decreased
peristalsis with slowing of intestinal transit explain the symptoms. However, even though an increased prevalence of several
common gastrointestinal motor disorders occurs in older
people, ageing per se appears to have minor direct effect on
most gastrointestinal functions, in large part because of the
functional reserve capacity of the gastrointestinal tract [1].
In our study, multiple regression analyses with age, gender,
body mass index and tobacco smoking as explaining variables
were used to evaluate the separate effect of each variable on
gastrointestinal motility. The analyses showed that advanced
age did not inXuence gastric emptying, postprandial frequency
of antral contractions or small intestinal transit rate, whereas
the older subjects had a longer colonic mean transit time than
the young subjects. The process of normal ageing, therefore, seems to reduce the propulsive efWcacy of the colon.
The effect of ageing on gastric motility has evoked some
interest, but it is still controversial whether gastric emptying
changes in advanced age. The present observation is consistent
with most of the previous reports [10–12]. However, other
studies showed that radiolabelled liquids or digestible solids
Gastrointestinal motor function
Figure 2. Small intestinal transit of liquid and solid marker in
16 older and 16 young volunteers. Horizontal bars indicate
mean values.
emptied more slowly from the stomach in older subjects
[13, 14]. In the majority of these studies, the magnitude of
the changes were relatively small, so that the emptying rates
were, for the most part, within the range observed in the
younger subjects. A plausible mechanism leading to slower
gastric emptying in older persons has not been deWned. In a
previous study, Clarkston and his colleagues noticed a high
incidence of sympathetic or parasympathetic dysfunction in
a group of older subjects, but there was no relationship
between gastric emptying and autonomic nerve dysfunction
[14]. Our observation that ageing did not inXuence the postprandial frequency of antral contractions is in accordance
with the recent report from Shimamoto and his colleagues
[15]. The enteric nervous system that is considered to control
the frequency of the underlying gastric slow waves, therefore,
appears to be preserved during normal ageing. Overall, ageing
seems to have only minor effects on normal gastric motility.
So far, little attention has been directed towards small
intestinal motility in advanced age. In a previous study
based on ambulatory manometry, Husebye and Engedal
found that the changes of the migrating motor complex
were within the range of normality for young individuals
[16]. Furthermore, the investigaters noticed that the motility
patterns after a meal were normal. In another recent study,
the hydrogen breath test did not show any effect of ageing on
orocaecal appearance time of lactulose [14]. Our Wnding that
the propulsive activity of the small intestine was unchanged in
Figure 3. Colonic transit of liquid marker in 16 older and 16
young volunteers. Horizontal bars indicate mean values.
Table 1. Results of gastrointestinal motility assessments in
older and young healthy volunteers
Older volunteers (n = 16)
Young volunteers (n = 16)
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
GMTT (liquids) 1.37 (1.07–1.85) hours
GMTT (solids)
2.07 (1.32–3.03) hours
SIMTT (liquids) 4.95 (2.21–8.00) hours
SIMTT (solids)
4.77 (2.53–8.13) hours
CMTT
66 (29–98) hours
PPFAC
3.3 (2.8–3.6) per minute
1.59 (1.18–1.96) hours
2.12 (1.53–2.73) hours
4.24 (2.70–6.60) hours
3.87 (2.48–5.89) hours
39 (14–75) hours
3.2 (3.0–3.4) per minute
Values are means (ranges); GMTT, gastric mean transit time; SIMTT, small
intestinal mean transit time; CMTT, colonic mean transit time; PPFAC,
postprandial frequency of antral contractions.
Table 2. Overall effects of age, gender, body mass index
and smoking on gastrointestinal motility variables expressed
as results of multiple regression analysis
Age
Gender
BMI
Smoking
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
GMTT (liquids)
GMTT (solids)
SIMTT (liquids)
SIMTT (solids)
CMTT
PPFAC
P = 0.0540
P = 0.8084
P = 0.7791
P = 0.4345
P = 0.0008
P = 0.4574
P = 0.2349
P = 0.1761
P = 0.2544
P = 0.1502
P = 0.4123
P = 0.4082
P = 0.5027
P = 0.4577
P = 0.2123
P = 0.1540
P = 0.6249
P = 0.9338
P = 0.1783
P = 0.0766
P = 0.2478
P = 0.4156
P = 0.0022
P = 0.4450
BMI, body mass index; GMTT, gastric mean transit time; SIMTT, small intestinal
mean transit time; CMTT, colonic mean transit time; PPFAC, postprandial
frequency of antral contractions.
157
J. L. Madsen, J. Graff
older healthy volunteers is in accordance with these observations. Thus, it is unlikely that small bowel abnormalities
such as malabsorption and bacterial overgrowth are due to
age-related motility changes.
It is commonly assumed that complaints of chronic constipation, as well as alterations in colonic functioning, are natural
consequences of the process of normal ageing [17]. However, existing data do not clearly implicate colonic dysmotility
in healthy older adults and chronic constipation does appear to
be associated more frequently with abnormalities of reXex
mechanisms that control the rectal function [1]. The ageing
inXuence on colonic or whole gut transit rate has been the
subject of few previous studies, which were all based on
radiological principles [18–20]. None of these studies pointed
out signiWcant differences between young and older subjects,
although Metcalf and her colleagues noted a tendency
towards a longer mean colonic transit time in the older
subjects [19]. The current results indicate a frequent delay in
colonic transit during the seventh and eighth decade in
individuals that do not report constipation or straining at
defaecation. Age-related changes in both the neurons and the
receptors of the enteric nervous system might be responsible
for our observation. Thus, studies on ageing showed a
substantial reduction in the number of neurons in the
myenteric plexus [21] and an increased density of opioid
receptors in the colon of aged guinea pigs [22]. Accordingly,
speciWc opioid antagonists appeared to improve chronic
constipation in geriatric patients [23]. It should be recognised,
however, that variations in physical activity levels, eating
habits and psychological factors might have inXuenced our
recordings too.
Premenopausal women seem to have slower gastric
emptying than postmenopausal women and men [24, 25].
Probably, the delayed emptying is due to the high progesterone
level during the luteal phase of the menstrual cycle. In our
study, gastric emptying assessment in young women was
not done in a speciWc phase of the menstrual cycle and may
explain why, therefore, we did not Wnd gender-related differences in gastric emptying. In agreement with previous
reports, our study did not show important effects of gender
on small intestinal and colonic motility [12, 26].
We did not reveal a relationship between body mass
index and gastrointestinal motility. It is probable, however,
that we would have observed an effect of body composition
if volunteers with very low or very high body mass index
were included. It has been shown by others that obese people
might have faster gastric emptying than those non-obese [27].
To the best of our knowledge an effect of body composition on small bowel or colonic motility has not been documented so far.
Smoking and transdermal or intravenous administration
of nicotine has been shown to delay gastric emptying and
accelerate colonic and rectosigmoid transit [28, 29]. In partial
accordance with these reports, our study showed a considerably shorter colonic mean transit time among smokers
than non-smokers. The precise mechanism is not known,
but adrenergic as well as cholinergic systems in the gastrointestinal tract are activated by nicotine and the response
seems to depend on the ratio of receptor types present.
158
With a predominantly parasympathetic innervation of the
colon, the expected effect of nicotine should be an increased
motor activity that might explain our observation.
Key points
• No age-related changes were found in gastric emptying
rate and postprandial frequency of antral contractions.
• Ageing did not inXuence the small intestinal transit rate.
• The colonic transit was delayed in the older group.
Acknowledgement
This study was supported by grants from the Danish Hospital
Foundation for Medical Research, the Region of Copenhagen,
the Faroe Islands and Greenland.
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Received 8 April 2003; accepted in revised form 15 September
2003
Age and Ageing Vol. 33 No. 2  British Geriatrics Society 2004; all rights reserved
Determinants of sleep quality in the healthy
aged: the role of physical, psychological,
circadian and naturalistic light variables
BERNADETTE HOOD, DOROTHY BRUCK, GERARD KENNEDY
Department of Psychology, Victoria University, Australia
Address correspondence to: B. Hood, Department of Psychology, Victoria University, PO Box 14428, MCMC 8001, Australia.
Fax: (+61) 3 936 52218. Email: [email protected]
Abstract
Ageing is associated with a decrease in the quality of night-time sleep with 30% of aged persons experiencing chronic insomnia.
Treatment of insomnia typically involves the use of hypnotic medications and these have been associated with a range of
negative outcomes in this population cohort. The development of age-related insomnia has been linked, in part, to changes in
the strength of the circadian regulation of sleep, these changes typically leading to increased fragmentation of the sleep–wake
cycle. Management of insomnia may therefore be linked to strengthening of these regulatory control mechanisms. Previous
research has indicated that both daily activity levels and ambient light exposure may act as zeitgebers to consolidate sleep–
wakefulness cycles. The current study utilised a naturalistic design to explore the relationship between light, activity and
159