CANBERRA, AUSTRALIA — Depression and anxiety cause one area of the human brain to become “significantly” larger, according to an Australian study.
The study, published by Australian National University (ANU) researchers recently, looked at the brains of more than 10,000 people.
The study shows that depression alone causes the hippocampus, the part of the brain linked to memory and learning, to shrink.
And in contrast, they found that when depression and anxiety occur together the part of the brain linked to emotions, the amygdala, increases in size.
“Many studies looking at the effect of depression on brain do not account for the fact that people who have depression often experience anxiety too,” Daniela Espinoza Oyarce, the lead author of the study, said in a statement.
“We found people who have depression alone have lower brain volumes in many areas of the brain, and in particular the hippocampus.
“This becomes even more relevant later in life because a smaller hippocampus is a risk factor for Alzheimer’s disease and may accelerate the development of dementia.”
Those with both depression and anxiety experienced less shrinkage in many brain areas, a finding that Espinoza Oyarce said indicated that the true effect of depression on the brain has been underestimated.
“Anxiety lowers the effect of depression on brain volume sizes by 3 percent on average – somewhat hiding the true shrinking effects of depression,” she said.
“More research is needed into how anxiety lowers the effects of depression, but for the amygdala, perhaps anxiety leads to overactivity.”
It is estimated that 45 percent of Australians will experience a mental health condition at some point in their lifetime.
According to leading mental wellbeing support organization Beyond Blue in any one year around a million Australian adults have depression and more than 2 million have anxiety.