Social lifestyle determinants, including social isolation, are associated with risk factors for neurodegeneration, according to a new study published in the open access journal PLOS ONE by Kimie Shafighi of McGill University in Canada and colleagues.
Alzheimer’s disease and related dementias (ADRD) are a growing public health crisis with an annual global cost of more than $1 trillion in the US. There is increasing evidence that social isolation is associated with an increased risk of ADRD, but the links between social lifestyle and other known risk factors for ADRD are less well understood.
In the new work, researchers studied data on 502,506 participants in the UK Biobank and 30,097 people enrolled in the Canadian Longitudinal Study of Aging. Both studies had questionnaires that included questions about loneliness, frequency of social interaction, and social support.
Risk factors for ADRD
The study found a wide range of associations between potentially modifiable risk factors for ADRD and loneliness and lack of social support. Individuals who smoked more, drank excessively, experienced sleep disturbances, and did not participate in frequent light-to-vigorous physical activities all known risk factors for ADRDwere more likely to be lonely and lack social support.
For example, in the CLSA, increased regular participation in physical exercise with other people was associated with a 20.1% reduction in the likelihood of feeling lonely and a 26.9% reduction in poor social support.
Physical and mental health factors previously associated with ADRD, such as cardiovascular disease, visual or hearing impairment, diabetes, and neurotic and depressive behaviors, were also associated with both subjective and objective social isolation.
For example, in the UKBB, hearing difficulty with background noise corresponded to a 29.0% increase in the likelihood of feeling lonely and a 9.86% increase in the likelihood of a lack of social support. The odds of feeling lonely and lacking social support were also 3.7 times and 1.4 times higher, respectively, depending on the participant’s neuroticism score.
The authors concluded that social isolation, which can be modified more easily than genetic or underlying health risk factors, could be a promising target for preventive clinical action and policy interventions. Given the uncertain impact of social distancing measures imposed by COVID-19, our findings underscore the importance of examining the multilevel effect of social isolation to inform public health interventions for ADRD.
