NAFLD and cognitive decline in older adults: a longitudinal cohort study

Nonalcoholic Fatty Liver Disease (NAFLD) is increasing in older adults, but no evidence exists on the longitudinal association between NAFLD and cognitive decline at old ages. The aim of this 7-year longitudinal study was to examine whether presence of NAFLD at baseline and/or its change (i.e. progression or regression) over the follow up predict the rate of cognitive decline over the same timeframe in older adults, independent of potential confounders. Participants included 457 community dwelling men and women aged 65 to 87 (mean ±SD: 70.9±4.1) years old, living near Bologna (Northern Italy). Global cognitive status was evaluated using Mini-mental State Examination (MMSE). Hepatic steatosis was assessed by abdominal ultrasound and categorized as absent, mild, moderate or severe. Participants were also classified into three subgroups according to their progression, stability or regression in hepatic steatosis over the follow up. Generalized estimating equation (GEE) models with 30 minus MMSE total score as the dependent variable with a Poisson distribution were used to test the longitudinal associations. Covariates included demographics, education, activities of daily living, alcohol, smoke, body mass index (BMI), waist circumference, hypertension, dyslipidemia, diabetes, insulin resistance and inflammation. As results, I found no significant association between baseline presence/severity of hepatic steatosis and either cross-sectional cognitive status or longitudinal rate of cognitive decline (P> .05). In addition, participants who underwent regression in the degree of hepatic steatosis over the follow-up presented accelerate cognitive decline over the same timeframe compared to the rest of the population, independent of covariates and even after adjusting for longitudinal change in BMI and waist circumference (P= .03). A nested sensitivity analysis confirmed this trend even when including only participants starting from moderate-severe hepatic steatosis at baseline. In conclusion, the present study suggests that in older adults NAFLD regression rather than progression is associated with accelerated cognitive decline.