Loneliness is associated with risk of cognitive impairment in the Survey of Health, Ageing and Retirement in Europe

Objectives To test whether loneliness is associated with the risk of cognitive impairment up to 11 years later in a European sample of middle-aged and older adults. The study examines whether this association is independent of measures of social isolation, depression, and other risk factors for cognitive impairment and dementia. Methods Participants (N = 14 114) from the Survey of Health, Ageing and Retirement in Europe (SHARE) answered a single item on loneliness at baseline and were assessed for cognitive impairment every 2-to-3 years for 11 years. Participants who scored at least 1.5 standard deviations below the age-graded mean on both a memory recall task and verbal fluency task were classified as impaired. A three-item measure of loneliness was available for a sample of respondents followed up to 4 years. Results Feeling lonely was associated with increased risk of incident cognitive impairment (HR = 1.31, 95%CI = 1.19-1.44), after accounting for age, sex, education, and SHARE country strata. The association was robust but reduced in magnitude when controlling for clinical and behavioral risk factors, health-related activity limitations, social isolation, social disengagement, and depressive symptoms. The association was not moderated by socio-demographic factors and was also apparent when using the three-item loneliness scale instead of the single-item measure. Conclusions These findings expand the extant literature on loneliness and the risk of cognitive impairment in older adulthood. Loneliness is one modifiable factor that can be intervened prior to the development of severe impairment or dementia.