Poor metabolic health, also known as “metabolic syndrome”, is defined as having three or more of the following: a large waist circumference, high triglycerides, high blood pressure, high blood sugar, and lower levels of high-density lipoprotein (HDL) cholesterol, sometimes known as ‘good’ cholesterol. Previous studies have shown that having poor metabolic health could increase the risk of developing dementia, but it was unclear whether it is linked to worse brain health even in people who do not have dementia. Maintaining both brain structure and cognitive abilities are crucial for healthy ageing as the loss of both can negatively impact brain health and might indicate progression towards dementia. The researchers investigated whether having poor metabolic health affected brain volume and cognitive abilities by analysing results from 37,395 UK Biobank participants who did not have dementia; 7,945 of the participants had poor metabolic health when they joined the UK Biobank study. Interestingly, our findings show that it is also associated with worse brain health even in individuals without dementia.