People who have non-alcoholic fatty liver disease – a build up of fat cells in the liver – may have a higher risk of dementia, according to a new study.
The research also indicates that people with the disease, who also have heart disease or who have had a stroke, might have an even higher risk of dementia.
Research suggests non-alcoholic 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 do not know they have it, but when there are symptoms these can include fatigue and pain or discomfort in the upper right abdomen.
While excessive alcohol use can cause fatty liver disease, non-alcoholic fatty liver disease can be due to obesity and related conditions like high blood pressure or type 2 diabetes.
Study author Ying Shang, of the Karolinska Institute in Stockholm, Sweden, said: “Common risk factors for both non-alcoholic fatty liver disease and dementia include metabolic disorders like high blood pressure, diabetes and obesity.
“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.”
In the study, researchers looked at 30 years of national Swedish patient registry records and identified 2,898 people aged 65 and older who were diagnosed with non-alcoholic fatty liver disease.
They also identified 28,357 people without the disease who were matched for age, sex and city of residence at age of diagnosis.
Researchers followed the patients up for an average of more than five years, and found that 145 with non-alcoholic fatty liver disease, or 5%, were diagnosed with dementia, compared to 1,291 people without liver disease, or 4.6%.
When other factors, like high blood pressure and diabetes, were taken into consideration, the study found that when compared to people without liver disease, those with non-alcoholic fatty liver disease had a 38% higher rate of dementia overall.
When looking specifically at vascular dementia, which is caused by inadequate blood flow to the brain, researchers found people with non-alcoholic fatty liver disease had a 44% higher rate than people without liver disease.
They did not find a higher rate of Alzheimer’s disease.
According to the study, people with liver disease who also had heart disease had a 50% greater risk of dementia.
And those who had liver disease and stroke had more than a 2.5 times greater risk of dementia.
Ms Shang added: “These results highlight the possibility that targeted treatment of this form of liver disease and co-occurring cardiovascular disease may reduce the risk of dementia.”
Dr Rosa Sancho, head of research at Alzheimer’s Research UK, said: “This finding highlights the fact that our brains don’t operate in isolation from the rest of our body and improving our physical health can help to reduce our risk of dementia and support a healthy brain.
“Current evidence suggests that being physical and mentally active, staying socially connected, not smoking, only drinking in moderation, eating a balanced diet, and keeping cholesterol and blood pressure levels in check can all play a part in improving brain health.”
The findings are published in the Neurology journal.