Does self-reported sleep quality predict poor cognitive performance among elderly living in elderly homes?

OBJECTIVES: Sleep complaints are common among elderly, especially institutionalized elderly, as they experience poorer sleep quality and higher use of sedative hypnotics, when compared to community-dwelling elderly. Recent findings suggest that there may be a relationship between poor quality of sleep and cognitive deficits. This study aimed at studying the relation between sleep quality and cognitive performance in older adults living in elderly homes. METHOD: 100 elderly living in an elderly home in El Mansoura, Egypt, were recruited in this study, 50 cases with subjective poor quality of sleep and 50 controls with subjective good quality of sleep as assessed by Pittsburgh sleep quality index (PSQI). Each participant went through comprehensive geriatric assessment (CGA), including geriatric depression scale (GDS), assessment of cognitive function by mini mental state examination (MMSE). RESULTS: 52% of poor sleepers showed impaired MMSE, while only 24% of good sleepers had impaired MMSE. Both orientation and (attention and calculation) were more affected (P = 0.027 and 0.035, respectively). Linear correlation coefficient between PSQI and different variables revealed significant negative correlation with total MMSE score, attention and calculation. CONCLUSION: Poor quality of sleep is related to cognitive impairment among elderly living in elderly homes and this problem should be taken in consideration among this group of elders.

Changes in glutamate decarboxylase enzyme activity and tau-protein phosphorylation in the hippocampus of old rats exposed to chronic mild stress: reversal with the neuronal nitric oxide synthase inhibitor 7-nitroindazole.

Effects of chronic stress are not completely understood. They may underlie depression and dementia. This study assessed the association between chronic stress, glutamate levels, tau-protein phosphorylation, and nitric-oxide in old rats exposed to chronic mild stress (CMS). Old (>15 months) male Wistar rats were exposed to CMS. Comparison groups included old and young control rats, young CMS-exposed, and old CMS-exposed rats treated with the neuronal nitric-oxide synthase (nNOS) enzyme inhibitor, 7-nitroindazole (20 mg/kg/day i.p.). Hippocampal glutamate levels and glutamate decarboxylase (GAD) activity were determined and tau protein phosphorylation was assessed. Age was a significant (p=0.025) source of variation in glutamate level [811.71+/-218.1, 665.9+/-124.9 micromol/g tissue protein (M+/-SD) in young and old control rats, respectively]. Old rats exposed to CMS were characterized by an increased risk to develop anhedonia. There was significant (p=0.035) decrease in GAD enzyme activity (-60.06%) and increased tau protein hyperphosphorylation in old rats exposed to CMS compared to control. Administration of 7-nitroindazole to CMS-exposed old rats significantly (p=0.002) increased GAD activity, decreased glutamate levels (7.19+/-3.19 vs. 763.9+/-91 micromol/g tissue protein; p=0.0005), and decreased phosphorylation of tau proteins compared to CMS exposed rats.