Abstract
INTRODUCTION: Prior studies have observed associations between poverty measured at single or across diffuse periods of the life course and cognitive function measured in later life. Few studies examine the relationship between cumulative poverty exposure and midlife cognition or address confounding of this relationship by early-life cognitive ability. METHODS: To estimate the effect of cumulative poverty with midlife cognitive function, we analysed data from National Longitudinal Survey of Youth 1979 participants with ≥3 family income measures over a 20-year period (1990-2010) who completed the modified Telephone Interview for Cognitive Status when ~48 years of age (N=2923). We defined participants' cumulative poverty status by the proportion of their family income measures <200% of the Federal Poverty Limit: 0 (never), <1/3 but >0 (sometimes), ≥1/3 but less than all (often) and all (always). Armed Forces Qualification Test score defined early-life cognitive ability. We used linear regression models to examine the association between cumulative poverty and sample-standardised z-scores for memory, attention and global cognitive function. RESULTS: Overall, 37.9% of participants were never, 26.6% were sometimes, 27.5% were often and 8.0% were always in poverty. In fully adjusted models and relative to participants never in poverty, those often (beta: -0.13; 95% CI -0.23 to -0.04) and always (beta: -0.37; 95% CI -0.53 to -0.22) in poverty had lower z-scores for midlife global cognitive function. Likewise, their z-scores were lower for midlife memory function. CONCLUSIONS: Longer durations of poverty exposure may be more detrimental for midlife cognition. This relationship was not fully explained by early-life cognitive ability.