An important part of the brain’s memory center appears to shrink in people with depression: ScienceAlert

It has long been known that depression He has Links to dementia And also specifically For Alzheimer’s diseaseBut how depression and cognitive decline might interact with each other remains unclear.

Now it seems that scientists have discovered a new piece of the puzzle, even if it’s a piece that opens up a lot of new questions.

In a study published in Translational psychiatryResearchers found that people with depression showed a reduction in the volume of a part of the brain necessary for memory processes. Hippocampus.

“Depression has long been associated with an increased risk of developing diabetes Alzheimer’s disease disease, but we still do not fully understand the biological relationship between the two.” He says Neuroscientist and first author Danielle Lu of the University of Southern California (USC).

“By looking closely at individual parts of the hippocampus, we have identified a particular region that may be particularly sensitive to depression in older people.”

The hippocampus is often thought of as Brain memory centerBut in fact it includes many structural subareas that perform different types of memory, learning and navigation functions.

And in the new study – on which it was based Magnetic resonance imaging and pet Screening more than 2,000 cognitively impaired adults aged 50 to 90 – about a third of them had depression – the researchers found that one area of ​​the hippocampus looked different in depressed participants.

This region, a complex region called CA23DG, combines… Hippocampal subfields CA2 and CA3along with a sub-area called Dentate gyrus.

After taking into account factors such as age, gender, body mass index and physical activity levels, CA23DG was found to be smaller in people with depression compared to non-depressed participants.

when Alzheimer’s disease Risk factors were included in the analysis – with researchers observing levels Amyloid and tau proteins in the brainor existence APOE ε4 genetic variant -CA23DG binding was largely unchanged, suggesting that known risk factors for Alzheimer’s disease were not involved in the reduction in CA23DG size.

What this means will need to be explored further in additional studies, but one explanation is that we are looking at two different mechanisms that could affect memory. The hippocampal changes seen in CA23DG may be a distinct phenomenon, unrelated to other biological features of Alzheimer’s disease.

In the baseline level analysis, other regions of the hippocampus – CA1 and – were assessed Small room – There does not appear to be a decrease in volume in people with depression.

But when the researchers took… Use of antidepressants As a factor, they found that people in the study who used antidepressants showed a reduction in the volume of both CA23DG and CA1.

“This seems counterintuitive, as medications should serve to ameliorate the harmful physiological effects of depression in the long term, thus acting as a protective factor against further damage to the hippocampus.” Write in their paper.

“People with severe depression may be more likely to be prescribed depression medications than those with milder depressive symptoms.”

On a similar note, the researchers found that people who had suffered from depression longer (even if their symptoms were controlled and milder) showed a stronger association with lower CA23DG volume than people who had worse depression but were also more likely to be newly diagnosed.

This suggests that the duration of depression may be a factor that can influence changes in the hippocampus, and not just the level of severity of recent symptoms.

But even then, the researchers admit, based on the data here, we don’t know for sure.

“It is possible that the drugs themselves are causing the connection to the hippocampal structure.” The study authors explain. “The effects we see are probably more related to the use of the medication than to the longer duration of depression.”

We will need more research to understand what drives these changes in the hippocampus in people with depression, and for now, these results only show an association — they do not prove that depression or antidepressants are causing CA23DG shrinkage.

For this reason, the research team urges people with depression not to make any sudden changes based on the results.

Related to: There are actually two biologically distinct forms of major depression, a new study says

“In this study, we cannot separate the potential effects of medications from the effects of the severe depression for which the medications are prescribed.” Lou says.

“Long-term studies that follow people before and after treatment will be necessary to understand these relationships. Our results should not be interpreted as a reason for anyone to change or stop taking prescribed medications.”

The results were reported in Translational psychiatry.