"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," write Robert S. Wilson, PhD, of the Rush University Medical Center in Chicago, Illinois, and colleagues. "We examined these issues using data from the Rush Memory and Aging Project, a longitudinal clinicopathologic study of risk factors for chronic conditions of old age."Source Medscape
Lonely elderly patients are more than twice as likely to develop Alzheimer's disease (AD)-like dementia than those who are not lonely, according to the results of a 4-year cohort study reported in the February issue of the Archives of General Psychiatry. However, pathology did not reveal Alzheimer's disease or cerebral infarction, suggesting that novel mechanisms may be involved.
"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," write Robert S. Wilson, PhD, of the Rush University Medical Center in Chicago, Illinois, and colleagues. "We examined these issues using data from the Rush Memory and Aging Project, a longitudinal clinicopathologic study of risk factors for chronic conditions of old age."
At baseline and annually thereafter for up to 4 years, 823 participants recruited from senior citizen facilities in and around Chicago, underwent uniform in-home evaluations including detailed cognitive function testing, clinical classification of dementia and AD, and assessment of loneliness with a modified version of the de Jong-Gierveld Loneliness Scale. For participants who died, uniform postmortem evaluation of the brain quantified AD pathologic abnormalities and cerebral infarction.
On the 5-item loneliness scale, mean baseline score was 2.3 ± 0.6. During follow-up, 76 subjects developed clinical AD, based on previously established composite measures of global cognition and specific cognitive functions.
Compared with persons who were not lonely (score, 1.4; 10th percentile), risk for AD was more than doubled in lonely persons (score, 3.2; 90th percentile). Controlling for indicators of social isolation did not affect this 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 during the study, and mean degree of loneliness was robustly associated with cognitive decline and with development of clinical AD.
In 90 participants who died and had brain autopsy, loneliness was unrelated to summary measures of AD pathology or to cerebral infarction.
"Loneliness is associated with an increased risk of late-life dementia but not with its leading causes," the authors write.
Study limitations include predominantly white volunteer cohort, mean observation period less than 3 years, only 76 cases of incident AD, and only 90 autopsies performed.
"The perception of being alone was associated with cognitive decline and development of an AD-like dementia even after controlling for objective indexes of social isolation and other covariates," the authors conclude. "Neither AD pathology nor cerebral infarction could account for the association, suggesting that novel neurobiologic mechanisms may be involved."
The National Institute on Aging and the Illinois Department of Public Health supported this study. The authors have disclosed no relevant financial relationships.
Arch Gen Psychiatry. 2007;64:234-240.
Clinical Context
Little is known about the association of dementia and emotional isolation, although social isolation, defined as having a small social network, being unmarried, and participating in few activities with others, has been associated with increased risk for dementia.
This is a prospective cohort study within the Rush Memory and Aging Project, a longitudinal clinicopathologic study of risk factors for chronic diseases of old age. Loneliness was assessed using a modified version of the de Jong-Gierveld Loneliness Scale, and patients were followed up for incidence of AD and cognitive impairment, and brain autopsies were performed at death.
Study Highlights
Inclusion criteria were absence of dementia and living in retirement communities, subsidized housing, local churches, or social services agencies.
At baseline, all participants underwent structured history, cognitive testing, and comprehensive assessment for AD.
The criteria for AD were from the joint working group of the National Institute of Neurological and Communicative Disease Disorders and Stroke-Alzheimer Disease and Related Disorders Association.
A modified version of the de Jong-Gierveld Loneliness Scale with a 5-point Likert scale was used for self-reported symptoms of loneliness.
Social isolation was assessed by social network size and frequency of participation in social activity, rated on a 5-point scale.
Depressive symptoms were assessed with a 10-item form by the Center for Epidemiological Studies–Depression scale for 9 cognitive activities.
Physical functioning was assessed using the Health Interview Survey.
At each annual evaluation thereafter, 20 cognitive tests were administered including the Mini-Mental State Examination and 19 tests with 7 measures of episodic memory.
A composite measure based on all 19 test results was used to quantify cognitive decline.
Postmortem brain autopsy was performed in subjects who died.
857 subjects completed at least one follow-up evaluation.
Mean follow-up period was 3 years.
Mean age was 81 years, 76% were women, mean years of education was 14 years, 91% were white, 66% lived in retirement homes, 30% in single family homes, and 4% in assisted-living settings.
Loneliness was negatively correlated to social network size, frequency of social activity, and cognitive activity and education.
76 subjects developed dementia that met AD criteria.
Those who developed AD were older, more likely to be men, had lower cognitive function, lower income, and higher levels of loneliness and disability.
The risk for AD increased by 51% for each point on the loneliness scale (relative risk [RR], 1.51).
A person with a high degree of loneliness (90th percentile for score) was 2.1 times more likely to develop clinical AD compared with someone with a low degree of loneliness (10th percentile for score).
More frequent social activity was associated with reduced AD risk (RR, 0.52).
Loneliness was inversely related to level of cognitive activity.
The association of loneliness with AD was unchanged after adjustment for race, income, disability, and vascular risk factors.
Loneliness was inversely related to baseline level of function on each cognitive measure.
Loneliness was associated with more rapid decline in global cognition, semantic memory, perceptual speed, and visuospatial ability.
There was no significant change in loneliness during the study.
135 subjects died, and brain autopsy was performed on 90 subjects.
Baseline loneliness score was unrelated to a global measure of AD pathology identified by silver stain, percentage area occupied by amyloid plaques, and density of neurofibrillary tangles.
The authors concluded that the association between loneliness and AD or cognitive decline was not mediated by AD pathology or cerebral infarction.
Pearls for Practice
In elderly persons, those with loneliness vs those without loneliness have an increased risk for AD-like dementia.
Loneliness is not related to AD pathologic findings or cerebral infarction.
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