Sensory-cognitive associations are only weakly mediated or moderated by social factors in the Canadian Longitudinal Study on Aging

Anni Hämäläinen,Natalie Phillips,Walter Wittich,M Kathleen Pichora-Fuller,Paul Mick

doi:10.1038/s41598-019-55696-5

Abstract

Sensory and cognitive function both tend to decline with increasing age. Sensory impairments are risk factors for age-related cognitive decline and dementia. One hypothesis about sensory-cognitive associations is that sensory loss results in social isolation which, in turn, is a risk factor for cognitive decline. We tested whether social factors are associated with cognitive and sensory function, and whether sensory-cognitive associations are mediated or moderated by social factors. We used cross-sectional data from 30,029 participants in the Canadian Longitudinal Study of Aging, aged 45–85 years, who had no reported cognitive impairment or diagnosis of dementia. We found strong independent associations of self-reported social variables with hearing (pure-tone audiometry), vision (pinhole-corrected visual acuity), and executive function and weaker associations with memory. The moderating and mediating effects of social variables on sensory-cognitive associations were weak and mostly non-significant, but social factors could be slightly more important for females and older people. Partial retirement (relative to full retirement or not being retired) may have protective effects on cognition in the presence of hearing loss. These findings confirm the association between social factors and sensory and cognitive measures. However, support is weak for the hypothesis that social factors shape sensory-cognitive associations.

Highlights

Cognitive and sensory impairments are frequently comorbid in older adults[1,2,3,4,5,6,7,8,9]
Exclusion criteria included living in institutions, living on First Nations reserves, full-time service in the Canadian Armed Forces, inability to respond in English or French, and cognitive impairment suspected by Canadian Longitudinal Study of Aging (CLSA) staff
The non-significant effect of participation frequency on executive function may be partially due to the moderate correlation between social participation types and frequency (Fig. 1) such that the variance associated with social participation may be captured by the number of types of participation rather than by participation frequency

Summary

Introduction

Cognitive and sensory impairments are frequently comorbid in older adults[1,2,3,4,5,6,7,8,9]. Cognitive decline has been hypothesized to result from long-term sensory deprivation, possibly because cognitive health is compromised by reduced social activity due to sensory impairments This is consistent with evidence suggesting that social isolation increases the risk of cognitive decline and dementia[10,16]. To examine sensory-cognitive-social associations, we used baseline cognitive, sensory, social, and health data from community-dwelling older adults who participated in the Canadian Longitudinal Study of Aging (CLSA,[20]). They were deemed to be cognitively normal and had no self-reported diagnosis of dementia. We test whether (1). cognitive measures are independently associated with measures of social factors; (2). previously observed sensory-cognitive associations (Phillips et al unpublished) remain significant after controlling for social factors; and (3). sensory-cognitive associations are moderated or mediated by social factors

Methods

Results

Conclusion