WP22/17: Is there an association between life-course social isolation and brain age

Working Paper 2022/17

An acute indicator of social connectedness is the degree to which an individual is isolated, i.e. lacking contact with others. There has been growing recognition of social isolation as a significant threat to public health and well-being that requires intervention at a societal level (Holt-Lunstad, et al., 2017; Leigh-Hunt, et al., 2017).

Dementia – a syndrome of progressive cognitive impairment affecting mainly older people – is a major cause of disability, dependency, and death among older people (WHO, 2017). Recent systematic reviews have concluded that a lack of social contact is associated with elevated dementia risk (Desai, et al., 2020; Kuiper, et al., 2015), while longitudinal studies have shown that social isolation is related to cognitive decline in older adults (Lara, et al., 2019; Luo & Li, 2021; Shankar, et al., 2013).

‘Brain age’ can be used as a marker of cognitive decline that may lead to dementia. Magnetic resonance imaging (MRI) measures of brain structure can be analysed to estimate biological brain age (Franke, et al., 2019; MacDonald & Pike, 2021). Relatively greater brain age has been shown to predict accelerated cognitive decline and dementia risk (Franke & Gaser, 2012).

Using data from the Dunedin Study, we have recently identified four distinct life-course trajectory groups of social isolation (low, increasing, decreasing, and high; Lay-Yee, et al., 2021). This study will investigate the relationship between these life-course trajectories of social isolation and brain age – as a biomarker of cognitive decline.

We will use data from the Dunedin Multidisciplinary Health and Development Study on social isolation, ages 5–38, and brain age measures taken from MRI assessments at age 45.

Loneliness Across the Life Course

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