Researchers have discovered a potential link between liver fat and brain ageing. According to Reuters on Friday, a type of fatty liver disease that is not related to excess drinking has exhibited greater brain shrinkage than what normally happens with age.

Scientists from the University of Haifa in Israel found that reduced brain volume was linked to non-alcoholic fatty liver disease (NAFLD). The disease adds the equivalent of an extra 4.2 years of ageing for people in their 60s and early 70s. Meanwhile, it added an extra 7.3 years of ageing for people under the age of 60.

The report was published in JAMA Neurology. It's the latest study to establish that people with NAFLD have impaired thinking and decreased brain activity compared with others.

To understand why, the researchers used MRI scans to measure the overall brain volume of 766 middle-aged men and women. Then, they utilised abdominal CT scans to examine their livers. Some 18% of the participants had fatty liver disease.

In an email to Reuters, lead author Galit Weinstein from the School of Public Health at the University of Haifa in Israel said that the research team accounted for other risk factors for brain ageing, such as blood fat levels, heart disease, diabetes, smoking, alcohol consumption, excess weight, lack of exercise and menopausal status.

The researchers found that people with NAFLD had more harmful risk factors than those without the disease. However, even after adjusting the study to encompass these risks, NAFLD was associated with significantly smaller total brain size. This was apparent even in people aged 75 and older, adding an equivalent of an extra 1.5 years of brain ageing compared to peers without fatty liver disease.

Significantly NAFLD didn't appear to be associated with other signs of brain injury or stroke. The researchers noted that NAFLD can be improved by lifestyle changes, like healthy eating and increased physical activity.

"This is extremely important when it comes to brain health, because currently there is usually no cure for neurodegenerative diseases, such as Alzheimer's disease. But it still remains to show in other studies that improvement in fatty liver disease is associated with lower risk of such brain diseases," Weinstein said.

"Fatty liver can be prevented by conducting appropriate lifestyle and diet," Weinstein added. "In turn, if one retains a healthy liver, his/her risk for other diseases, such as diabetes and heart diseases, is also reduced. In this study, we show that keeping a healthy liver may also be linked with a healthier brain."