Loneliness and lack of social support are associated with classical risk factors of Alzheimer disease and related dementias (ADRD). These findings were published in PLoS One.
Researchers sought to investigate an association between social lifestyle determinants of subjective loneliness and objective social support with major ADRD risk factors.
They used data from the UK Biobank (UKBB), a prospective epidemiological cohort with more than 500,000 participants recruited from across Great Britain. The current investigation (N=502,506; 54.4% women; mean age 56.5±8.1 years, 40-69 years of age when recruited) included a second cohort from the Canadian Longitudinal Study of Aging (CLSA) (N=30,097; 50.9% women; mean age 63.0±10.3 years, 44-89 years of age at enrollment) recruited from 11 cities in 10 provinces in Canada, with baseline data last collected in 2015.
To determine loneliness, UKBB participants were asked, “Do you often feel lonely” Yes/No. CLSA participants were asked, “How often do you feel lonely?” with a positive answer indicating all of the time (5-7 days).
To determine social support, UKBB participants were asked, “How often are you able to confide in someone close to you?” Their response was used as an objective measure of the frequency of social interactions. Researchers denoted lack of social support as confiding less than “daily or almost daily” (positive answer) vs confiding in others more often (negative answer). CLSA participants were asked if they had, “Someone to confide in or talk to about yourself or your problems?” with answers less than “all of the time” or “most of the time” considered positive.
In the UKBB cohort, they noted the first mode (they mapped for 7 partial least squares [PLS] modes) explained the largest fraction of variation with a canonical correlation rho of 0.471 between the sets of variables. Interindividual differences in social richness dominated by loneliness (0.682) and lack of social support (0.437) were strongly paired with the personality traits among the ADRD risk factors, and the neuroticism score (0.408). In the UKBB, the neuroticism score is defined as a composite score of 12 neurotic behavioral domains, including loneliness. Higher scores indicate higher degree of neurotic behavior (0-12). They found social determinants across the 7 modes were related to societal factors (income), mental health factors (personality), and lifestyle factors (exercise).
Regarding the CLSA cohort, they found that the variance in the first mode (rho=0.500) was interpreted by interindividual differences in lack of social support (0.512) and loneliness (0.652) among the social factors, and by watching TV (0.321) and getting a positive screen for depression (0.364) for the risk traits.
UKBB and CLSA analysis with PLS showed the risk factors of ADRD were reflected in the examined social determinants from lifestyle, mental health, and societal in at least 1 of the joint variation modes. However associations with physical health measures were consistently weak. The social domain of the first mode in both cohorts was dominated by lack of social support and loneliness.
Researchers noted in both cohorts, individuals who excessively drank alcohol, experienced sleep disturbances, smoked more, and failed to frequently participate in daylight to vigorous physical activities were more likely to be lonely and lack social support. In the UKBB, there was a 19.7% increase in the odds of feeling lonely associated with a higher number of cigarettes smoked. In the CLSA, there was a 20.1% decrease in the odds of feeling lonely and a 26.9% decrease in having poor social support with increased regular participation in physical exercise with other people.
In the UKBB, there was a 29.0% increase in the odds of feeling lonely and a 9.86% increase in the odds of lacking social support for individuals with difficulty hearing with background noise. There were reduced levels of loneliness and better social support for individuals who used a hearing aid.
In the UKBB, as a function of the neuroticism score, odds of feeling lonely were 3.7 times greater and odds of lacking social support were 1.4 times greater. Researchers noted in both cohorts feelings of happiness linked strongly with reduced loneliness and poor social support.
“Our findings show a large array of associations between these (classical risk factors of ADRD) potentially modifiable risk factors and both loneliness and lack of social support,” researchers concluded. They wrote, “Our collective findings underscore the importance of exploring subjective and objective social isolation in depth to inform policy interventions, especially among the elderly,” and added “Compared to other ADRD risk factors, such as ApoE4 genotype, social isolation is arguably easier to modify, and therefore, particularly promising to target and alter.”
Shafighi K, Villeneuve S, Rosa Neto P, et al. Social isolation is linked to classical risk factors of Alzheimer’s disease-related dementias. PLoS One. Published online February 1, 2023. doi:10.1371/journal.pone.0280471