Scientists have established a link between depression and damage to specific areas of the brain for the first time.
Researchers at the University of Aberdeen were able to show that the location of lesions deep in the brains of elderly test subjects had a bearing on whether the damage would lead to a physical impairment, cognitive difficulty or depressive symptoms.
People with higher levels of intelligence and better physical fitness in early life were also shown to be less likely to suffer from depression in old age, according to the study, published in the journal Archives of Gerontology and Geriatrics.
Previous studies have established the link between brain lesions, usually caused by blood vessel disease, and depression. Brain lesions deep within the structure of the organ have now been shown to be linked to depression, while those on the cerebellum or brain stem are more likely to cause physical impairment.
Depression affects one in five elderly people, rising to two in five for those in residential care, according to the Royal College of Psychiatrists. With the elderly population increasing, the study’s authors say their discovery will contribute to the understanding of an illness that can be difficult to diagnose accurately.
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“What this is relevant to is frailty in the elderly,” Alison Murray, professor of radiology at the University of Aberdeen, said. “We know that as people get older, they don’t usually get single ailments, they tend to decline on a number of fronts.
“These things often coexist, so people become a bit cognitively impaired, their mood is low, they’re less physically able, or a combination of all three. What this research indicates is that you can map out which is likely to be the main outcome, depending on where the lesions are.”
The research involved carrying out MRI scans of 240 people in the Aberdeen Birth Cohort, a group of people born in the city in 1936, who were assessed in primary school, forming a benchmark for future research.
Higher levels of intelligence and better physical fitness reduced the risk of depressive symptoms even in people with deep brain lesions, the study found.
“This supports the whole concept that exercise is good for brain and mood and can reduce depressive symptoms,” Professor Murray said.
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“In terms of practical applications, this research means that in the future, we can use this information to identify those at greater risk of depressive symptoms and in doing so target appropriate people to treat.”
The research feeds into a larger study being undertaken at the University of Edinburgh that aims to improve the poor understanding of risk factors for depression in the wider population.
“We’re collecting data on people across Scotland and looking at depression and trying to identify the life-course risk factors. Depression is an over-arching term that can be linked to a number of illnesses underneath that.
“This study is to look at a much larger number of people, with deep brain MRI [results] like this, at how we can better understand what the risk factors for depression are.”