Is Non-Alcoholic Fatty Liver Disease Connected with Cognition? The Complex Interplay between Liver and Brain

The prevalence of non-alcoholic fatty liver disease (NAFLD) and its progressive form, non-alcoholic steatohepatitis (NASH), is increasing in parallel with the rising rates of obesity and type 2 diabetes. Approximately one in four adults are diagnosed with liver steatosis globally. NAFLD is associated with insulin resistance, hypertension, obesity, visceral adiposity, and dyslipidaemia. These risk factors are often accompanied by inflammation and oxidative stress, which also play a role in extrahepatic diseases, including conditions related to the central nervous system, such as mild cognitive impairment and Alzheimer’s disease. The number of people living with dementia is approximately 55 million and is estimated to increase to approximately 2 billion people by 2050. Recent studies have found that NAFLD is associated with poorer cognition. The aim of this review was to summarise the findings of hitherto studies that have linked NAFLD with cognition and dementia, as well as to discuss the potential liver–brain pathways.