Social lifestyle determinants, including social isolation, are associated with neurodegeneration risk factors, according to a new study by Kimia Shafighi of McGill University, Canada, and colleagues published in the open-access journal PLOS ONE. Alzheimer’s disease and related dementias (ADRD) is a growing public health crisis with an annual global cost of over US$1 trillion. There is increasing evidence that social isolation is associated with an increased risk of ADRD, but the relationship between social lifestyle and other known ADRD risk factors is less well understood.
In the new work, the researchers studied data from 502,506 UK Biobank participants and 30,097 people enrolled in the Canadian Longitudinal Study of Aging. Both studies had questionnaires that included questions about loneliness, frequency of social contact, and social support. The study found a large number of associations between potentially modifiable ADRD risk factors and both loneliness and lack of social support. Individuals who smoke excessively, drink excessively, experience sleep disturbances, and often fail to participate in moderate to vigorous physical activity—all known risk factors for ADRD—are more likely to be lonely and lack social support. had more possibilities. For example, in CLSA, an increase in regular participation in physical exercise with others was associated with a 20.1% decrease in the odds of feeling lonely and a 26.9% decrease in the odds of having poor social support.
Physical and mental health factors previously associated with ADRD, such as heart disease, vision or hearing loss, diabetes, and neurotic and depressive behaviors, were associated with both subjective and objective social isolation. In the UKBB, for example, difficulty hearing with background noise corresponded to a 29.0% increase in the odds of feeling lonely and a 9.86% increase in the odds of lacking social support. The odds of feeling lonely and lacking social support were 3.7 and 1.4 times higher, respectively, as a function of a participant’s score for neuroticism. The authors conclude that social isolation, which is more easily modifiable than genetic or underlying health risk factors, may be a promising target for preventive clinical action and policy interventions. The authors say: “Given the uncertain impact of social distancing measures imposed by COVID-19, our findings underline the importance of examining the multilevel effect of social isolation to inform public health interventions for ADRD.”