This study examined the association between loneliness and risk of incident all-cause dementia and whether the association extends to specific causes of dementia.

Longitudinal.

Community.

Participants were from the UK Biobank (N = 492,322).

None.

Loneliness was measured with a standard item. The diagnosis of dementia was derived from health and death records, which included all-cause dementia and the specific diagnoses of Alzheimer’s disease (AD), vascular dementia (VD), and frontotemporal dementia (FTD), over 15 years of follow-up.

Feeling lonely was associated with a nearly 60% increased risk of all-cause dementia (HR = 1.59, 95% CI = 1.51–1.65; n = 7,475 incident all-cause). In cause-specific analyses, loneliness was a stronger predictor of VD (HR = 1.82, 95% CI = 1.62–2.03; n = 1,691 incident VD) than AD (HR = 1.40, 95% CI = 1.28–1.53; n = 3135 incident AD) and was, surprisingly, a strong predictor of FTD (HR = 1.64, 95% CI = 1.22–2.20; n = 252 incident FTD). The associations were robust to sensitivity analyses and were attenuated but remained significant accounting for clinical (e.g. diabetes) and behavioral (e.g. physical activity) risk factors, depression, social isolation, and genetic risk. The association between loneliness and all-cause and AD risk was moderated by APOE ϵ4 risk status such that the increased risk was apparent in both groups but stronger among non-carriers than carriers of the risk allele.

Loneliness is associated with increased risk of multiple types of dementia.

Loneliness functionally varies and is determined by the degree of interaction with others. We examined weekly fluctuations in reported loneliness as a function of frequency of social interactions in old age. We hypothesized that emotional and social components of loneliness would be related to different types of social relationships.

Participants reported their feeling of loneliness and their social interaction quantity (frequency of meetings) via a weekly based diary, over 6 weeks.

Diary study.

The study included 55 older adults with different dwelling arrangements (M = 73.4, SD = 6.97).

Measures of Loneliness (the De Jong-Gierveld Loneliness Scale), Social Interaction and Contact, and sociodemographic parameters were used.

Social and emotional loneliness fluctuated over the course of the 6-week study. Frequency of meeting friends was related to emotional loneliness and total feelings of loneliness. Frequency of meeting close/trusted figures was related to emotional loneliness which appeared the following week. Other variables were not associated with either changes in loneliness or its dimensions.

Loneliness in old age is changeable. The emotional component of loneliness seems to be dominant in determining overall feelings of loneliness and is more sensitive to externally chosen social interaction.

The COVID-19 pandemic greatly impacted the social lives of older adults across several areas, leading to concern about an increase in loneliness. This study examines the associations of structural, functional, and quality aspects of social connection with increased loneliness during COVID-19 and how these associations vary by sociodemographic factors.

Secondary data analyses on a nationally representative survey of older US adults.

The 2020 Health and Retirement Study (HRS) COVID-19 module.

The study sample includes 3,804 adults aged 54 or older.

Increased loneliness was based on respondents’ self-report on whether they felt lonelier than before the COVID-19 outbreak.

While 29% felt lonelier after COVID-19, middle-aged adults, women, non-Hispanic Whites, and the most educated were more likely to report increased loneliness. Not having enough in-person contact with people outside the household was associated with increased loneliness (OR = 10.07, p < .001). Receiving emotional support less frequently (OR = 2.28, p < .05) or more frequently (OR = 2.00, p < .001) than before was associated with increased loneliness. Worse quality of family relationships (OR = 1.85, p < .05) and worse friend/neighbor relationships (OR = 1.77, p < .01) were related to feeling lonelier. Significant interactions indicated stronger effects on loneliness of poor-quality family relationships for women and insufficient in-person contact with non-household people for the middle-aged group and non-Hispanic Whites.

Our findings show an increase in loneliness during COVID-19 that was partly due to social mitigation efforts, and also uncover how sociodemographic groups were impacted differently, providing implications for recovery and support.