Scientists in the US have found a link between symptoms of depression and changes in memory. The findings are published today (Wednesday 9 May) in the scientific publication, Neurology.
The researchers studied over 1,000 stroke-free volunteers, who completed tests of memory, thinking and depressive symptoms as well as having an MRI scan to study the brain’s structure.
The study found that 22% of the volunteers were classed as having ‘greater depressive symptoms’, and these volunteers were more likely to be female, Hispanic and taking anti-depressants.
The volunteers completed a series of tests to assess memory and thinking skills, including verbal memory. Researchers also carried out MRI scans, to study the brain’s structure.
The memory tests done at the start of the study revealed that people with greater symptoms of depression had worse episodic memory – the ability to recall specific events in the past. A decline in episodic memory is a well-recognised early symptom of Alzheimer’s disease.
When the scientists looked at the structure of the brain on MRI scans, they found that people with greater symptoms of depression also tended to have a smaller brain size and changes to the brain’s blood vessels. However, the size of the hippocampus – part of the brain important for memory – did not change in those with greater depressive symptoms.
Researchers also measured changes in people’s memory and thinking over an average of five years but found no link between changes in memory and thinking and more severe symptoms of depression.
Dr David Reynolds, Chief Scientific Officer at Alzheimer’s Research UK, said:
“We know that there is a link between depression and memory loss, but it’s been difficult to pin down the exact nature of this relationship. This study did find several brain changes associated with greater symptoms of depression, but the size of the brain region involved in memory was no different and people’s thinking skills over five years remained the same.
“It’s difficult to draw firm conclusions from the study as we don’t know if anyone had or developed dementia before, during or after the study. It’s important to understand how health and lifestyle factors can influence long-term dementia risk, but it’s still not clear whether depression contributes to memory problems or vice versa. To continue to unpick this link we need to see sustained investment in dementia research.”