Background: Lifestyle and vascular factors have been linked to cognitive decline and dementia, but the role of dietary fats for cognitive impairment is less clear. Objectives: To investigate the association of midlife dietary fat intake to cognitive performance, and to the occurrence of clinical mild cognitive impairment (MCI) later in life in a non-demented population. Methods: Participants of the Cardiovascular risk factors, Aging and the Incidence of DEmentia (CAIDE) study (n=1409) were derived from random, population-based samples studied in midlife and re-examined in late-life (follow-up of 20.9 years). A wide variety of cognitive tests were conducted for assessing global cognitive function, episodic, semantic and prospective memory, psychomotor speed, and executive function. Altogether 82 (5.8%) subjects were diagnosed as having clinical MCI. The demented subjects (n=68) were excluded from the current analyses. Dietary information was collected with a structured questionnaire and an interview. Logistic regression analyses were used to calculate associations between dietary fat intake and the risk of clinical MCI. To analyze the effect of fat intake on cognition, analyses of covariance (ANCOVA) were applied in multivariate models. Results: Abundant saturated fat (SFA) intake from milk products and spreads at midlife was associated with poorer global cognitive function and prospective memory and with an increased risk of clinical MCI (OR 2.36, 95% CI 1.17-4.74) after adjusting for demographic and vascular factors, other fats and ApoE. On the contrary, higher intake of polyunsaturated fatty acids (PUFA) was associated with better semantic memory. Also frequent fish consumption was associated with better global cognitive function and semantic memory. Further, higher PUFA-SFA ratio was associated with better psychomotor speed and executive function. Conclusions: Our data suggests that dietary fat intake at midlife affects cognitive performance and the occurrence of clinical MCI in late-life. Thus, dietary interventions may modify cognitive performance and the risk of clinical MCI.
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