Diabetes and cardiovascular disease increase dementia risk, study finds

People with at least two of the diseases type 2 diabetes, heart disease and stroke have double the risk of developing dementia, according to a new study.

Those who are living with more than one of the conditions, known as cardiometabolic diseases, showed an accelerated speed of cognitive decline and double the risk of cognitive impairment and dementia, expediting their development by two years, researchers in Sweden said.

Type 2 diabetes and heart diseases are some of the main risk factors for dementia, a syndrome associated with an ongoing decline of brain functioning.

Dementia develops slowly over decades. It first manifests as gradual cognitive decline that only shows up in cognitive tests and then degenerates into cognitive impairment, affecting a person's memory.

Researchers at the Karolinska Institutet in Sweden studied the links between cardiometabolic diseases and dementia.

“Few studies have examined how the risk of dementia is affected by having more than one of these diseases simultaneously, so that’s what we wanted to examine in our study,” Abigail Dove, a doctoral student at the Aging Research Centre, part of the Department of Neurobiology, Care Sciences and Society, Karolinska Institutet, said.

“In our study, the combinations of diabetes/heart disease and diabetes/heart disease/stroke were the most damaging to cognitive function,” she added.

Individuals who had just one cardiometabolic disease did not display a significantly higher risk of dementia.

“This is good news", Ms Dove said. "The study shows that the risk only increases once someone has at least two of the diseases, so it’s possible that dementia can be averted by preventing the development of a second disease.”

The correlation between cardiometabolic diseases and the risk for dementia was stronger in the participants who were under 78 years old, according to the study, published in the Alzheimer’s & Dementia journal.

“We should therefore focus on cardiometabolic disease prevention already in middle age, since the risk of cognitive failure and dementia appears higher among those who develop a cardiometabolic disease earlier in life,” Ms Dove added.

For their study, the researchers extracted data from the Swedish National Study on Aging and Care on a total of 2,500 healthy, dementia-free individuals over the age of 60 living on Kungsholmen in Stockholm.

At the start of the study, the incidence of cardiometabolic diseases was assessed through medical records and clinical investigation.

The participants were then followed for twelve years with medical examinations and cognitive tests in order to monitor changes in cognitive ability and the development of dementia.

The presence of more than one cardiometabolic disease accelerated the speed of cognitive decline and doubled the risk of cognitive impairment and dementia, expediting their development by two years.

The magnitude of the risk was increased with a greater number of diseases.