Every day we seemingly learn about the discovery of another factor or factors linked to a higher risk of dementia. The dementia risk factor du jour is liver disease – specifically, non-alcoholic fatty liver disease – a buildup of fat cells in the liver. According to a new study from the Karolinska Institute in Stockholm, Sweden, the liver disease may confer a higher risk of dementia. This form of liver disease in patients with heart disease or who have had a stroke may have an even higher risk of dementia.
Non-alcoholic fatty liver disease is the most common chronic liver disease, affecting up to 25 percent of people worldwide. It is underdiagnosed because people often do not have symptoms. This could lead to underestimating the association between non-alcoholic fatty liver disease and dementia. If symptoms are present, they include pain or discomfort in the upper right abdomen and fatigue.
Excessive alcohol use can cause fatty liver disease, but non-alcoholic fatty liver disease is far more common. It is often due to obesity or metabolic conditions, such as type 2 diabetes or high blood pressure. In a small percentage of people, it can lead to liver inflammation or liver damage.
“Common risk factors for both non-alcoholic fatty liver disease and dementia include metabolic disorders like high blood pressure, diabetes and obesity,” says Ying Shang, PhD, of the Karolinska Institute. “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 other risk factors.”
Researchers looked at Swedish patient registry records and identified 2,898 people aged 65 and older who were diagnosed with non-alcoholic fatty liver disease. They then identified 28,357 people without the disease who were matched for age, sex, and city of residence at time of diagnosis.
After adjustment for cardiovascular risk factors like high blood pressure and diabetes, they found that when compared to people without liver disease, people with non-alcoholic fatty liver disease had a 38% higher rate of dementia.
Looking specifically at vascular dementia caused by inadequate blood flow to the brain, people with non-alcoholic fatty liver disease had a 44% higher rate of dementia than people without liver disease. Researchers did not find a higher rate of Alzheimer’s disease.
People with liver disease who also had heart disease had a 50 percent greater risk of dementia. Those who had liver disease and stroke had more than a 2.5 times increased risk.
“Our study shows that non-alcoholic fatty liver disease is associated with the development of dementia, which may be driven mainly by vascular damage in the brain,” says Shang. “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.”
The study is published in the journal Neurology.