As you get older, your chances for getting dementia rises steadily. One in 100 people in their late 60s have dementia, while this rises to 6 in 100 people in their late 70s, and as many as 20 in 100 in their late 80s. There are many factors that are thought to play a role in the development of the condition; a family history of dementia, your lifestyle, and if you have certain health conditions, such as diabetes, high blood pressure and high cholesterol.
Previous research has also suggested that older people with depression are more likely to develop Alzheimer’s disease – the most common type of dementia – but very few studies have looked into the impact of depression on other types, including vascular dementia. If you have Alzheimer’s disease, small lumps of protein form in your brain. Vascular dementia, on the other hand, occurs when blood vessels in or near your brain become damaged, so your brain cells don’t get enough blood and die.
For the study, the researchers examined the findings of 23 studies looking at nearly 50,000 people over the age of 50. People with depression were compared to those who weren’t affected by the mental health disorder, and the researchers tried to determine whether one group was more likely than the other to develop Alzheimer’s disease and vascular dementia. Half of the studies lasted for at least five years, with some going on for 17 years.
When the researchers eliminated the studies that didn’t account for factors that can increase dementia risk, such as age and health, they discovered that people with depression had twice the risk of vascular dementia than those who didn’t have depression. However, we can’t be certain that people had a higher risk of dementia solely because of their depression, as other factors – such as lifestyle and other health issues – might have played a role.