The impact of social relationships on cognitive performance in the older adult : emotional loneliness is detrimental to cognitive performance : a thesis presented in partial fulfilment of the requirements for the degree of Doctor of Clinical Psychology at Massey University, Palmerston North

Abstract

The present study examined the influence of loneliness and objective social isolation on cognitive performance at baseline (time 1) and after two years (time 2) among older adults aged 65 - 84 years old. The exploration of the moderating role of objective social isolation on the relationship between loneliness and cognitive performance was investigated. The role education may have in moderating the relationship between loneliness, objective social isolation and cognitive performance was also investigated. This study extends previous work on loneliness and social isolation, and cognition in two ways. While previous research has found a link between loneliness, objective social isolation, and cognition, many studies have considered loneliness and objective social isolation independent of each other when investigating their relationship with cognition. This study investigated the relative and synergistic relationship between loneliness, objective social isolation and cognition. Secondly, Weiss (1973) conceptualised loneliness as emotional loneliness or social loneliness. Social loneliness as a risk factor for cognitive performance in the older adult has been overlooked. This study considered both emotional loneliness and social loneliness, as two different forms of loneliness that may influence cognition in the older adult. The current study examined the impact of three different types of social isolation (emotional loneliness, social loneliness and objective social isolation) on global cognition and cognitive domains (memory, fluency, language and visuospatial ability). Pre-existing data from the New Zealand Longitudinal Study of Ageing (NZLSA; 2010 and 2012) was used for analysis. The relationships between emotional loneliness, social loneliness and objective social isolation were examined using standard quantitative statistical procedures with linear hierarchical multiple regression being the primary technique. Results showed that loneliness (emotional and social) and objective social isolation may be differentially important for cognitive performance in the older adult. Emotional loneliness had an association with global cognition, verbal fluency, language and visuospatial ability, though not memory at baseline. At the two year follow-up emotional loneliness had an association with global cognition, memory, language, and visuospatial ability, though not verbal fluency. Social loneliness did not have an association with cognition at baseline, and was found to be a suppressor variable at the two year follow-up. Objective social isolation had an association at baseline with visuospatial ability only, which did not carry through to the two year analysis. Novel findings were that older adults who were emotional lonely and not socially isolated had poorer cognitive performance at baseline for global cognition, language and visuospatial tasks, than those who were emotionally lonely and socially isolated. Also older adults who had low levels of education and were socially isolated performed better in visuospatial tasks at baseline than older adults with low levels of education who were not socially isolated. Explanations of why emotional loneliness influence cognition is discussed, with a focus on the ‘lonely in the crowd’ subsample of older adults. Limitations of the study and implications for future research, such as need for longitudinal research that includes control variables such as personality factors, stress and sleep is also discussed.