Context: Social isolation in old age has been associated with risk of developing dementia, but the risk associated with perceived isolation, or loneliness, is not well understood.Objective: To test the hypothesis that loneliness is associated with increased risk of Alzheimer disease (AD).Design: Longitudinal clinicopathologic cohort study with up to 4 years of annual in-home follow-up.Participants: A total of 823 older persons free of dementia at enrollment were recruited from senior citizen facilities in and around Chicago, Ill. Loneliness was assessed with a 5-item scale at baseline (mean±SD, 2.3±0.6) and annually thereafter. At death, a uniform postmortem examination of the brain was conducted to quantify AD pathology in multiple brain regions and the presence of cerebral infarctions. Main Outcome Measures:Clinical diagnosis of AD and change in previously established composite measures of global cognition and specific cognitive functions.Results: During follow-up, 76 subjects developed clinical AD. Risk of AD was more than doubled in lonely persons (score 3.2, 90th percentile) compared with persons who were not lonely (score 1.4, 10th percentile), and controlling for indicators of social isolation did not affect the finding. Loneliness was associated with lower level of cognition at baseline and with more rapid cognitive decline during follow-up. There was no significant change in loneliness, and mean degree of loneliness during the study was robustly associated with cognitive decline and development of AD. In 90 participants who died and in whom autopsy of the brain was performed, loneliness was unrelated to summary measures of AD pathology or to cerebral infarction. Conclusion:Loneliness is associated with an increased risk of late-life dementia but not with its leading causes.

Little is known about the relative benefits of cognitively stimulating activities at different points in the lifespan. In a cohort of 576 older persons without dementia, we assessed current and past (childhood, young adulthood, middle age) frequency of cognitive activity; availability of cognitively stimulating resources in the home in childhood and middle age; and 5 domains of cognitive function. Past cognitive activity and cognitive resources were positively correlated with both current cognitive activity and current cognitive function. The association with cognitive function was reduced after controlling for current cognitive activity, however. Current cognitive activity was associated with better cognitive function, especially semantic memory and perceptual speed, even after controlling for past activity. The results suggest that past cognitive activity contributes to current cognition principally through its association with cognitive activity in old age. (JINS, 2005,11, 400–407.)

We examined the association of diverse measures of social engagement with level of function in multiple cognitive domains in 838 persons without dementia who had a mean age of 80.2 (SD = 7.5). Social network size, frequency of social activity, and level of perceived social support were assessed in linear regression models adjusted for age, sex, education, and other covariates. Social activity and social support were related to better cognitive function, whereas social network size was not strongly related to global cognition. The results confirm that higher level of social engagement in old age is associated with better cognitive function but the association varies across domains of social engagement.Social engagement refers to maintenance of social connections and participation in social activities (Bassuk, Glass, & Berkman, 1999). Recent research suggests that older people who are more socially engaged tend to have a higher level of cognitive function (Barnes, Mendes de Leon, Bassuk et al., 1999;Holtzman et al., 2004;Yeh & Liu, 2003;Zunzunegui, Alvarado, del Ser, & Otero, 2003) compared to less engaged persons. With few exceptions (Barnes et al., 2004), these studies have not assessed nonsocial experiences such as cognitive activity and physical activity that have also been associated with level of cognitive function (Dustman, Emmerson, & Shearer, 1994;Wilson et al., 1999) and rate of cognitive decline (Weuve et al., 2004;. Thus, the Copyright © Taylor & Francis Group, LLC Address correspondence to Kristin R. Krueger, 600 S. Paulina Street, Suite 1038, Chicago, IL 60612. kris2blink@yahoo.com. Publisher's Disclaimer: Full terms and conditions of use: http://www.informaworld.com/terms-and-conditions-of-access.pdf This article may be used for research, teaching and private study purposes. Any substantial or systematic reproduction, re-distribution, reselling, loan or sub-licensing, systematic supply or distribution in any form to anyone is expressly forbidden. The publisher does not give any warranty express or implied or make any representation that the contents will be complete or accurate or up to date. The accuracy of any instructions, formulae and drug doses should be independently verified with primary sources. The publisher shall not be liable for any loss, actions, claims, proceedings, demand or costs or damages whatsoever or howsoever caused arising directly or indirectly in connection with or arising out of the use of this material. In the present study, we examined the relation of social engagement to level of cognitive function in older persons from the Rush Memory and Aging Project, a clinical-pathologic study of risk factors for common chronic conditions of old age. We used three measures of social engagement: social network size, frequency of participation in social activities, and perceived level of social support. Cognition was assessed with a battery of 19 performance tests administered in an approximately 1-h session. Based in part on a factor analysis of the tests at baseline, composit...

The results suggest that higher extraversion and lower neuroticism are associated with reduced risk of mortality in old age and that these associations are mediated in part by personality-related patterns of cognitive, social, and physical activity.