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J. L. Madsen, J. Graff References 1. The World Bank. Chapter 1, The Changing World. In World Development Report 1999/2000 New York: Oxford University Press, 1999: 31–50. 2. Asplund K, Carlberg B, and Sundström G. Stroke in the elderly. Observations in a population-based sample of hospitalized patients. Cerebrovasc Dis 1992; 2: 152–7. 3. Di Carlo A, Lamassa M, Pracucci G et al. Stroke in the very old: clinical presentation and determinants of 3-month functional outcome: A European perspective. European BIOMED Study of Stroke Care Group. Stroke 1999; 30: 2313–9. 4. Sharma JC, Fletcher S, Vassallo M. Strokes in the elderly – higher acute and 3-month mortality – an explanation. Cerebrovasc Dis 1999; 9: 2–9. 5. Jamrozik K, Broadhurst RJ, Forbes S, Hankey GJ, Anderson CS. Predictors of death and vascular events in the elderly : the Perth Community Stroke Study. Stroke 2000; 31: 863–8. 6. Hackett ML, Duncan JR, Anderson CS, Broad JB, Bonita R. Health-related quality of life among long-term survivors of stroke: results from the Auckland Stroke Study, 1991–1992. Stroke 2000; 31: 440–7. 7. Jørgensen HS, Nakayama H, Raaschou HO, Gam J, Olsen TS. Silent infarction in acute stroke patients. Prevalence, localization, risk factors, and clinical signiWcance: the Copenhagen Stroke Study. Stroke 1994; 25: 97–104. 8. Jørgensen HS, Nakayama H, Raaschou HO, Olsen TS. Effect of blood pressure and diabetes on stroke in progression. Lancet 1994; 344: 156–9. 9. Jørgensen HS, Plesner AM, Hübbe P et al. Marked increase of stroke incidence in men between 1972 and 1990 in Frederiksberg, Denmark. Stroke 2001; 23: 1701–4. 10. World Health Organisation. Stroke–1989. Recommendations on stroke prevention, diagnosis, and therapy. Report of the Age and Ageing 2004; 33: 154–159 DOI: 10.1093/ageing/afh040 WHO Task Force on Stroke and other Cerebrovascular Disorders. Stroke 1989; 20: 1407–31. 11. Scandinavian Stroke Study Group. Multicenter trial of hemodilution in ischemic stroke–background and study protocol. Stroke 1985; 16: 885–90. 12. Lindenstrøm E, Boysen G, Christiansen LW, Hansen BR, Nielsen PW. Reliability of the Scandinavian Neurological Stroke Scale. Cerebrovasc Dis 1991; 1: 103–7. 13. Statistical Package for Social Sciences for Windows®. Version 9.0. Chicago, IL: SPSS, 1998. Computer Programme. 14. Norusis MJ. Logistic regression analysis. In SPSS for Windows, Advanced Statistics. Chicago, IL: SPSS, 1993: 1–30. 15. Wolf PA, Abbott RD, Kannel WB. Atrial Wbrillation: a major contributor to stroke in the elderly. The Framingham Study. Arch Intern Med 1987; 147: 1561–4. 16. Kelly-Hayes M, Wolf PA, Kannel WB, Sytkowski P, D’Agostino RB, Gresham GE. Factors inXuencing survival and need for institutionalization following stroke: the Framingham Study. Arch Phys Med Rehabil 1988; 69: 415–18. 17. Bonita R, Anderson CS, Broad JB, Jamrozik KD, StewartWynne EG, Anderson NE. Stroke incidence and case fatality in Australasia. A comparison of the Auckland and Perth population-based stroke registers. Stroke 1994; 25: 552–7. 18. Petty GW, Brown RD Jr, Whisnant JP, Sicks JD, O’Fallon WM, Wiebers DO. Survival and recurrence after Wrst cerebral infarction: a population-based study in Rochester, Minnesota, 1975 through 1989. Neurology 1998; 50: 208–16. 19. Dennis MS, Burn JP, Sandercock PA, Bamford JM, Wade DT, Warlow CP. Long-term survival after Wrst-ever stroke: the Oxfordshire Community Stroke Project. Stroke 1993; 24: 796–800. 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. References 1. Orr WC, Chen CL. Aging and neural control of the GI tract: IV. Clinical and physiological aspects of gastrointestinal motility and aging. Am J Physiol 2002; 283: G1226–31. 2. Firth M, Prather CM. Gastrointestinal motility problems in the elderly patient. Gastroenterology 2002; 122: 1688–700. 3. Camilleri M, Zinsmeister AR. Towards a relatively inexpensive, noninvasive, accurate test for colonic motility disorders. Gastroenterology 1992; 103: 36–42. 4. Bonapace ES, Maurer AH, Davidoff S, Krevsky B, Fisher RS, Parkman HP. Whole gut transit scintigraphy in the clinical evaluation of patients with upper and lower gastrointestinal symptoms. Am J Gastroenterol 2000; 95: 2838–47. 5. Graff J, Brinch K, Madsen JL. Gastrointestinal mean transit times in young and middle-aged healthy subjects. Clin Physiol 2001; 2: 253–9. 6. Brinch K, Larsson HBW, Madsen JL. A deconvolution technique for processing small intestinal transit data. Eur J Nucl Med 1999; 26: 272–6. 7. Madsen JL, Graff J, Fugisang S. A simpliWed method for processing dynamic images of gastric antrum. Nucl Med Commun 2000; 21: 1037–41. 8. Evans MA, Triggs EJ, Cheung M, Broe GA, Creasey H. Gastric emptying rate in the elderly: implications for drug therapy. J Am Geriatr Soc 1981; 29: 201–5. 9. Kupfer RM, Heppell M, Haggith JW, Bateman DN. Gastric emptying and small-bowel transit rate in the elderly. J Am Geriatr Soc 1985; 33: 340–3. 10. Moore JG, Tweedy C, Christian PE, Datz FL. Effect of age on gastric emptying of liquid–solid meals in man. Dig Dis Sci 1983; 28: 340–4. 11. Shay SS, Eggli D, McDonald C, Johnson LF. Gastric emptying of solid food in patients with gastroesophageal reXux. Gastroenterology 1987; 92: 459–65. 12. Madsen JL. Effects of gender, age, and body mass index on gastrointestinal transit times. Dig Dis Sci 1992; 37: 1548–53. 13. Horowitz M, Maddern GJ, Chatterton BE, Collins JP, Harding PE, Shearman DJ. Changes in gastric emptying rates with age. Clin Sci 1984; 67: 213–18. 14. Clarkston WK, Pantano MM, Morley JE, Horowitz M, LittleWeld JM, Burton FR. Evidence for the anorexia of aging: gastrointestinal transit and hunger in healthy elderly vs. young adults. Am J Physiol 1997; 272: R243–8. Sleep quality in ageing 15. Shimamoto C, Hirata I, Hiraike Y, Takeuchi N, Nomura T, Katsu K. Evaluation of gastric motor activity in the elderly by electrogastrography and the (13)C-acetate breath test. Gerontology 2002; 48: 381–6. 16. Husebye E, Engedal K. The patterns of motility are maintained in the human small intestine throughout the process of aging. Scand J Gastroenterol 1992; 27: 397–404. 17. Stewart RB, Moore MT, Marks RG, Hale WE. Correlates of constipation in an ambulatory elderly population. Am J Gastroenterol 1992; 87: 859–64. 18. Becker U, Elsborg L. A new method for the determination of gastrointestinal transit times. Scand J Gastroenterol 1979; 14: 355–9. 19. Metcalf AM, Phillips SF, Zinsmeister AR, MacCarty RL, Bearth RW, Wolff BG. SimpliWed assessment of segmental colonic transit. Gastroenterology 1987; 92: 40–7. 20. Nagengast FM, van der Werf SD, Lamers HL, Hectors MP, Buys WC, van Tongeren JM. InXuence of age, intestinal transit time, and dietary composition on fecal bile acid proWles in healthy subjects. Dig Dis Sci 1988; 33: 673–8. 21. Gabella G. Fall in the number of myenteric neurons in aging guinea pigs. Gastroenterology 1989; 96: 1487–93. 22. Culpepper-Morgan J, Holt PR, Kreek MJ. Increased mu and kappa opiate receptors in guinea pig colon with age (Abstract). Gastroenterology 1988; 94: A82. 23. Kreek MJ, Paris P, Bartol MA, Mueller D. Effects of short term oral administration of the speciWc opioid antagonist naloxone on fecal evacuation in geriatric patients (Abstract). Gastroenterology 1984; 86: A1144. Age and Ageing 2004; 33: 159–165 DOI: 10.1093/ageing/afh051 24. Petring OU, Flachs H. Inter- and intrasubject variability of gastric emptying in healthy volunteers measured by scintigraphy and paracetamol absorption. Br J Clin Pharmacol 1990; 29: 703–8. 25. Gryback P, Hermansson G, Lyrenas E, Beckman KW, Jacobsson H, Hellstrom PM. Nationwide standardisation and evaluation of scintigraphic gastric emptying: reference values and comparisons between subgroups in a multicentre trial. Eur J Nucl Med 2000; 27: 647–55. 26. Degen LP, Philips SF. Variability of gastrointestinal transit in healthy women and men. Gut 1996; 39: 299–305. 27. Tosetti C, Corinaldesi R, Stanghellini V et al. Gastric emptying of solids in morbid obesity. Int J Obes Relat Metab Disord 1996; 20: 200–5. 28. Scott AM, Kellow JE, Shuter B, Nolan JM, Hoschl R, Jones MP. Effects of cigarette smoking on solid and liquid intragastric distribution and gastric emptying. Gastroenterology 1993; 104: 410–16. 29. Rausch T, Beglinger C, Alam N, Gyr K, Meier R. Effect of transdermal application of nicotine on colonic transit in healthy non-smoking volunteers. Neurogastroenterol Motil 1998; 10: 263–70. 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