Low folate predicts accelerated cognitive decline: 8-year follow-up of 3140 older adults in Ireland

Objective To examine associations of plasma folate concentrations and risk of global and domain-specific cognitive decline in older people. Methods Data of 3140 participants from The Irish Longitudinal Study on Ageing (TILDA), a nationally-representative cohort of adults aged >= 50 years were used over 8-year follow-up. Biannual cognitive assessments included the Mini-Mental State Examination (MMSE), verbal fluency and immediate and delayed word recall tests (Waves 1-5) and the Montreal Cognitive Assessment, (MoCA) (Waves 1 and 3). Plasma folate concentrations were measured in stored blood collected at baseline. Mixed effects Poisson and linear regression determined associations between baseline folate concentrations and cognition. Results In multivariable-adjusted models of those aged >= 50 years at baseline, low folate at baseline (<11.2 nmol/L) was associated with higher proportions of MMSE errors (incidence rate ratio [IRR] = 1.10; 95% confidence interval [CI] (1.00, 1.21), lowest vs. highest quintile) over 8 years. Plasma folate <21.8 nmol/L predicted declines in episodic memory for immediate (beta [beta] = -0.26; 95% CI (-0.48, -0.03), beta = -0.29; 95% CI (-0.50, 0.08) and beta = -0.29; (-0.50, -0.08), for lowest three vs. highest quintile) and delayed recall (beta = -0.20; 95% CI (-0.38, -0.01), beta = -0.18; 95% CI (-0.37, -0.01) and beta = -0.19; (-0.36, -0.01) lowest three vs. highest quintile). There were no significant associations in a subsample aged >= 65 years. Conclusion In those aged >= 50 years, lower concentrations of folate may have differential relationships with cognitive domains. Folate <11.2 nmol/L predicted a decline in global cognitive function, while <21.8 nmol/L predicted poorer episodic memory. Low folate was associated with accelerated decline in cognitive function and is an important marker for cognitive decline among older people.

Automated summary

In individuals aged 50 and above, low plasma folate concentrations may be associated with different cognitive domains. Low folate is associated with a decline in global cognitive function and poorer episodic memory.