A person's dementia risk is shaped partly by factors that cannot be altered, including age, gender and genetics. Other influences may be modifiable, such as smoking, cardiovascular disease, high blood lipids, physical activity, alcohol consumption, hearing loss and high blood pressure.

Dementia is not a single disease. It is a collection of symptoms that can result from several different disorders, which means the risks may vary depending on the underlying cause. Researchers at Lund University examined how individual risk factors are connected to brain changes associated with Alzheimer's disease and vascular dementia.

"Much of the research available on the risk factors that we ourselves can influence does not take into account the different causes of dementia. This means that we have had limited knowledge of how individual risk factors affect the underlying disease mechanisms in the brain," explains Sebastian Palmqvist, senior lecturer in neurology at Lund University and senior physician at the Memory Clinic at Skåne University Hospital.

Researchers Tracked Brain Changes for Four Years

The study involved almost 500 participants who had an average age of 65 and showed no signs of cognitive impairment. Researchers followed them for four years, measuring changes in the brain's white matter, the nerve fibers that are often damaged in vascular dementia.

The team also monitored levels of amyloid β and tau, two proteins associated with Alzheimer's disease. Their goal was to determine how both modifiable and nonmodifiable risk factors were related to changes in the brain over time.

Vascular Risks Were Linked to White Matter Damage

Most of the modifiable factors examined, including smoking, cardiovascular disease, high blood lipids and high blood pressure, were associated with damage to blood vessels in the brain. They were also linked to a more rapid buildup of changes in white matter.

"We saw that most modifiable risk factors -- smoking, cardiovascular disease, high blood lipids and high blood pressure, among others -- were linked to damage to the brain's blood vessels and a faster accumulation of so-called white matter changes. This damage impairs the function of the blood vessels and leads to vascular brain damage - and can ultimately lead to vascular dementia," says Isabelle Glans, doctoral student at Lund University and resident in neurology at Skåne University Hospital.

The researchers also identified possible connections between certain risk factors and the proteins involved in Alzheimer's disease.

"Diabetes was associated with increased accumulation of amyloid β, while people with lower BMI had faster accumulation of tau. However, these findings need to be investigated further and validated in future studies," continues Isabelle Glans.

Healthy Habits May Reduce Multiple Forms of Damage

Adopting healthier habits and addressing modifiable risks may help delay the appearance of Alzheimer's symptoms. This may be especially important because many people with dementia have more than one type of disease process occurring in the brain, including both vascular damage and Alzheimer's related changes.

Palmqvist said that improving vascular and metabolic health may therefore remain valuable even for people at risk of Alzheimer's disease.

"Focusing on vascular and metabolic risk factors can still help reduce the combined effects of several brain changes that occur simultaneously," he concludes.