Publications

OBJECTIVES

To test whether the addition of melatonin to bright-light therapy enhances the efficacy in treating rest-activity (circadian) disruption in institutionalized patients with Alzheimer's disease (AD).

DESIGN

Randomized, controlled trial.

SETTING

Two nursing homes in San Francisco, California.

PARTICIPANTS

Fifty subjects (mean age 86) with AD.

INTERVENTION

Experimental subjects received 1 hour of morning light exposure (> or = 2,500 lux in gaze direction) Monday to Friday for 10 weeks and 5 mg melatonin (LM, n=16) or placebo (LP, n=17) in the evening. Control subjects (n=17) received usual indoor light (150-200 lux).

MEASUREMENTS

Nighttime sleep variables, day sleep time, day activity, day:night sleep ratio, and rest-activity parameters were determined using actigraphy.

RESULTS

Linear mixed models were employed to test the primary study hypotheses. No significant differences in nighttime sleep variables were found between groups. At the end of the intervention, the LM group showed significant improvement in daytime somnolence as indicated by a reduction in the duration of daytime sleep, an increase in daytime activity, and an improvement in day:night sleep ratio. The LM group also evidenced a significant increase in rest-activity rhythm amplitude and goodness of fit to the cosinor model.

CONCLUSION

Light treatment alone did not improve nighttime sleep, daytime wake, or rest-activity rhythm. Light treatment plus melatonin increased daytime wake time and activity levels and strengthened the rest-activity rhythm. Future studies should resolve the question of whether these improvements can be attributed to melatonin or whether the two zeitgebers interact to amplify efficacy.

OBJECTIVE

Older adults with type 2 diabetes are more likely to fall, but little is known about risk factors for falls in this population. We determined whether diabetes-related complications or treatments are associated with risk of falls in older diabetic adults.

RESEARCH DESIGN AND METHODS

In the Health, Aging, and Body Composition cohort of well-functioning older adults, participants reported falls in the previous year at annual visits. Odds ratios (ORs) for more frequent falls among 446 diabetic participants whose mean age was 73.6 years, with an average follow-up of 4.9 years, were estimated with continuation ratio models.

RESULTS

In the first year, 23[corrected]% reported falling; 22, 26, 30[corrected], and 31[corrected]% fell in subsequent years. In adjusted models, reduced peroneal nerve response amplitude (OR 1.50 -95% CI 1.07-2.12], worst quartile versus others); higher cystatin-C, a marker of reduced renal function (1.38 [1.11-1.71], for 1 SD increase); poorer contrast sensitivity (1.41 [0.97-2.04], worst quartile versus others); and low A1C in insulin users (4.36 [1.32-14.46], A1C 8%) were associated with risk of falls. In those using oral hypoglycemic medications but not insulin, low A1C was not associated with risk of falls (1.29 [0.65-2.54], A1C 8%). Adjustment for physical performance explained some, but not all, of these associations.

CONCLUSIONS

In older diabetic adults, reducing diabetes-related complications may prevent falls. Achieving lower A1C levels with oral hypoglycemic medications was not associated with more frequent falls, but, among those using insulin, A1C