Background and objectives: Nonalcoholic fatty liver disease (NAFLD) and dementia share common risk factors, including metabolic disorders. However, it is unclear whether NAFLD is associated with dementia risk. We investigated the association between NAFLD and dementia risk, as well as the role of cardiovascular complications, including heart disease and stroke. Methods: In this population-based matched cohort study, we identified all Swedish patients aged ≥65 years with NAFLD identified in the National Patient Registry (NPR) between 1987 and 2016. These were matched with up to ten reference individuals from the population. general in age, sex and municipality in the year of diagnosis. The diagnosis of incident dementia was derived from the NPR or Cause of Death Registry through 2016. Adjusted hazard ratios (aHRs) and 95% confidence intervals (CIs) were calculated with Cox regression models. Results: A total of 2898 patients with NAFLD and 28357 matched controls were identified (median age at entry, interquartile range [IQR], 70 [8]; 55.1% female). During a median follow-up of 5.5 years (IQR: 8.5 years), 145 (5.0%) NAFLD patients and 1291 (4.6%) reference individuals were diagnosed with dementia. Compared with control individuals, patients with NAFLD had higher rates of dementia (aHR 1.38, 95% CI 1.10–1.72) and vascular dementia (aHR 1.44, 95% CI 0.96 –2.23, p=0.07). Comorbid NAFLD and heart disease (aHR 1.50 95% 1.08–2.05) or stroke (aHR 2.60 95% CI 1.95–3.47) confer an increased risk of dementia. Discussion: Nonalcoholic fatty liver disease (NAFLD) had a modest association with higher rates of dementia. This was strongest among NAFLD patients diagnosed with cardiovascular comorbidities. Classification of evidence : This study provides Class II evidence that non-alcoholic fatty liver disease is associated with the development of vascular and non-vascular dementia. |
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People who have nonalcoholic fatty liver disease , a buildup of fat cells in the liver, may have an increased risk of dementia, according to a new study published in Neurology ®, the medical journal of the American Academy of Neurology. Researchers also found that people with this form of liver disease who also have heart disease or have had a stroke may have an even higher risk of dementia.
Nonalcoholic fatty liver disease affects up to 25% of people worldwide and is the most common chronic form of liver disease. Because there are often no symptoms, many people don’t know they have it. When people have symptoms, they may include fatigue and pain or discomfort in the upper right part of the abdomen. While excessive alcohol consumption can cause fatty liver disease, nonalcoholic fatty liver disease can be caused by obesity and related conditions, such as high blood pressure or type 2 diabetes. In a small percentage of people, it can cause inflammation or Hepatic injury.
"Common risk factors for both nonalcoholic fatty liver disease and dementia include metabolic disorders such as high blood pressure, diabetes, and obesity," said study author Ying Shang, PhD, of the Karolinska Institute in Stockholm, Sweden. “So our study sought to determine if there was a link between this form of liver disease and a person’s risk of dementia, independent of these risk factors.”
For the study, researchers looked at 30 years of Swedish patient records and identified 2,898 people aged 65 or older who were diagnosed with non-alcoholic fatty liver disease. The researchers then identified 28,357 people without the disease who were matched by age, sex, and city of residence at the age of diagnosis.
After an average of more than five years of follow-up, 145 people with nonalcoholic fatty liver disease, or 5%, were diagnosed with dementia, compared with 1,291 people without liver disease, or 4.6%.
Researchers adjusted for cardiovascular risk factors such as high blood pressure and diabetes and found that compared to people without liver disease, people with nonalcoholic fatty liver disease had a 38% higher overall rate of dementia. Looking specifically at vascular dementia caused by inadequate blood flow to the brain, researchers found that people with non-alcoholic fatty liver disease had a 44% higher rate than people without liver disease. The researchers did not find a higher rate of Alzheimer’s disease.
People with liver disease who also had heart disease had a 50% increased risk of dementia. Those who had liver disease and stroke had more than 2.5 times the risk of dementia.
“Our study shows that nonalcoholic fatty liver disease is associated with the development of dementia, which may be mainly driven by vascular damage in the brain,” Shang said. “These results highlight the possibility that targeted treatment of this form of liver disease and concurrent cardiovascular disease may reduce the risk of dementia.”
One limitation of the study was that nonalcoholic fatty liver disease is underdiagnosed because people often have no symptoms. Shang said this could lead to underestimating the association between non-alcoholic fatty liver disease and dementia.
The study was funded by the Swedish Research Council.
