Momentary loneliness and cognitive performance variability in daily life: an ecological momentary assessment study.

Loneliness is increasingly recognised as a dynamic risk factor for cognitive health outcomes, yet little is known about how momentary fluctuations in loneliness relate to cognitive functioning in daily life. In the current research, 157 mid-to-later life adults completed ecological momentary assessments five times per day for 20 days, reporting momentary loneliness and completing brief mobile cognitive tasks. Using Bayesian mixed-effects location-scale models, we examined within- and between-person associations between momentary loneliness and both levels and variability of cognitive performance across processing speed, working memory, and episodic memory. Results showed largely null and inconsistent associations between loneliness and overall cognitive performance (across cognitive domains). However, exploratory domain-specific analyses indicated that greater instability in momentary loneliness was associated with greater variability in processing speed and working memory. At the within-person level, greater momentary loneliness was associated with better and less variable episodic memory performance, with associations differing by social context, trait loneliness, and age. Overall, findings suggest that associations between loneliness and cognitive functioning in daily life may not be uniform but vary across cognitive domains, timescales, and contextual conditions, highlighting the importance of dynamic and context-sensitive models.