— Black Dog Institute (@blackdoginst) July 1, 2015
The researchers found 65% of the depressed study participants had recurrent depression and it was these people who had a smaller hippocampus, which is near the centre of the brain and is involved with long-term memory, forming new memories, and connecting emotions to those memories.
The findings of the largest international study to compare brain volumes in people with and without major depression were published in the medical journal Molecular Psychiatry.
The University of Sydney’s brain and mind research institute led the Australian arm of the study. Its co-director, Professor Ian Hickie, said those people in the study experiencing their first depressive episode had a normal hippocampus size.
“But the more episodes of depression a person had, the greater the reduction in hippocampus size,” he said.
“So recurrent or persistent depression does more harm to the hippocampus the more you leave it untreated. This largely settles the question of what comes first: the smaller hippocampus or the depression? The damage to the brain comes from recurrent illness.”