Loneliness and cognitive function in adults aged 50 years and older: a systematic review; and, Loneliness and psychotic-like experiences in middle-aged and older adults: the mediating role of selective attention to threat and external attribution biases
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Date
13/01/2023Author
Lucjan, Pawel
Metadata
Abstract
Loneliness is a common experience across the lifespan, including older age. It is linked with
multiple adverse health outcomes, such as anxiety, depression, or psychosis at the clinical
and subclinical levels. Furthermore, loneliness can influence human cognition and has been
associated with poorer cognitive function and biased information processing. With the world's
population growing older, it is of increasing importance to understand better how loneliness
affects the health and well-being of the ageing population. Furthermore, because of the wide
impact on health and the fact that loneliness can be effectively addressed, with the most
effective interventions targeting underlying social cognition, loneliness may be a viable target
of a broad range of interventions aiming at clinical populations as well as preventative
strategies for the general population.
Chapter one of this thesis presents the results of a systematic review of cross-sectional
and longitudinal studies on the association between loneliness and cognitive function in
middle-aged and older adults (age ≥ 50) without recognised cognitive impairment. A search of
six electronic databases supplemented by a manual search yielded twelve articles containing
thirteen studies from nine countries. The studies indicated that loneliness was weakly
associated with poorer global cognition in older adults without recognised cognitive
impairment and predicted accelerated cognitive decline. Most evidence came from studies
using the MMSE to assess global cognition. Findings from studies using other measures of
global cognition or specific cognitive domains were largely lacking and inconclusive.
Furthermore, the limitations of the evidence and the review more broadly are discussed,
including the clinical heterogeneity of included studies and measurement bias. Nevertheless,
we concluded that interventions promoting healthy cognitive ageing would benefit from
addressing loneliness as one of the risk factors. Future research directions are provided.
Chapter two presents the findings of an empirical study testing the hypothesis of whether
the association between loneliness and psychotic-like experiences was mediated by two
specific cognitive biases: selective attention to threat bias; and a tendency to attribute negative
events to external causes, such as other people. A convenience sample (n = 642) of middleaged
(40-59 years) and older adults (>60 years) was recruited online. This study found that
loneliness was associated with an increased rate of psychotic-like experiences. A parallel
mediation model indicated that two cognitive mechanisms mediated this association. Thus,
loneliness increased both attention to threat and external attribution bias, which in turn were
associated with an increased rate of psychotic-like experiences. This model proved robust
after adjusting for possible clinical and socio-demographic confounders, including anxiety and
depressive symptoms. The impact of age was observed as moderating factors. This study
demonstrates the feasibility of using the psychosis continuum framework in the ageing
population as an alternative to clinical studies. The study limitations and directions for future
research are also discussed.