It’s well-known that depression can take a toll on your mental health, but did you know it can affect other aspects of brain health, too?
“People with depression exhibit differences in their brain as revealed through neuroimaging,” says Avigail Lev, PsyD, a clinical psychologist with the Bay Area CBT Center in California. Research shows that, over long periods of time, these physical changes in the brain caused by depression could lead to changes in the way the brain functions.
For instance, these changes can make it harder for someone to focus on and complete their usual work-related or personal responsibilities or rely on their memory over time. This can cause additional stress or frustration in everyday life.
So, how exactly does depression change the brain? Here are four ways, according to experts.
1. Depression Can Cause Parts of the Brain to Shrink, Leading to Memory Problems
“Depression can take a toll on your memory, and this isn’t just a matter of forgetfulness,” says Brent Nelson, MD, an adult interventional psychiatrist and chief medical information officer at PrairieCare, a division of Newport Healthcare in St. Cloud, Minnesota.
The issue with depression and memory is not so much memory loss but obstacles to storing, consolidating, and retrieving memories, says Dr. Lev.
The connection between memory problems and depression may be related to changes in the brain. The hippocampus, a part of the brain that can be changed by depression, is essential for forming memories, explains Dr. Nelson. “Studies have found that the hippocampus can decrease in size and activity in those with long-standing depression,” he says.
Shrinkage of the hippocampus may be related to cortisol, a hormone released by the body in response to stress. “Chronic stress and elevated cortisol levels associated with depression can also contribute to hippocampal changes, resulting in memory effects,” says Nelson.
Specifically, research shows that the hippocampus is the part of the brain most exposed to high concentrations of cortisol. Long-term stress can lead neurons (brain cells) in the hippocampus to die, resulting in shrinkage of the hippocampus, the same research shows. Researchers are still learning whether the body’s release of cortisol itself or dysregulation with the body’s release of cortisol are what leads the hippocampus to shrink.
2. Depression May Contribute to Inflammation, Which Can Harm Brain Health
“There’s good evidence that depression contributes to inflammation, and, in general, depressed people have greater levels of inflammation than non-depressed people,” says James C. Jackson, PsyD, the director of behavioral health at the ICU Recovery Center in Nashville, Tennessee.
One theory for why people with depression have higher levels of inflammation is that stress may cause changes in the immune system. This may contribute to an increased inflammatory response from the central nervous system, which in turn might contribute to the development of depression, according to a review published in October 2021 in the Journal of Clinical Neurology.
Researchers don’t yet know exactly how the brain’s response to inflammation affects its networks — and if it’s the depression causing the inflammation or the other way around. One hypothesis is that inflammation caused by chronic stress disrupts neural pathways (connected brain cells that send signals from one part of the brain to another), potentially contributing to depression.
“Inflammation is harmful for the brain and likely contributes to adverse effects,” says Dr. Jackson. But how much depression contributes to inflammation versus the other way around is still not known, he adds.
3. Depression May Change the Prefrontal Cortex, Which Can Make It Harder to Pay Attention and Concentrate
“Executive functions, such as planning, decision-making, and problem-solving, can also be impaired by depression, leading to difficulties in daily life and work,” adds Nelson. “This is often due to dysfunction in the prefrontal cortex, a key brain region for executive functions.”
Changes to the prefrontal cortex may also affect mood, motivation, and attention among people with depression, according to a review published in CNS Neuroscience and Therapies.
According to the same review, prefrontal areas of the brain, such as the prefrontal cortex, experience significant decreases in thickness over time among people with depression.
When this happens, people with depression may experience executive dysfunction, meaning a person’s ability to manage their emotions, thoughts, and actions are disrupted. Executive dysfunction can also impact attention and concentration, says Jackson.
4. Depression’s Effects on the Prefrontal Cortex May Lead to Slower Processing Speed
Although the effects of depression on processing speed — “the speed at which you respond to questions, the speed at which you engage in conversation, the length of time it takes you to remember someone’s name,” Jackson explains — are not often talked about, these effects can have profound daily implications on someone’s life.
In a study published in 2019 in Progress in Neuro-Psychopharmacology and Biological Psychiatry, researchers gave neuropsychological tests to 106 people with current major depression, 119 people with remitted major depression (meaning the symptoms have subsided), and 120 controls without major depression, in order to study how depression affects processing speed, as well as learning and memory.
The results showed that people with current major depression had slower processing speed compared with both people with remitted major depression and controls.
Among those who have processing speed, attention, and concentration difficulties, the prefrontal cortex tends to show reductions in overall activity as well as reductions in synchronization with other regions, which means different parts of the brain might not be working together as well on complex tasks, explains Nelson.
Are the Brain Health Effects of Depression Permanent?
Researchers don’t yet know for sure whether the effects of chronic depression on the brain are permanent. But seeking professional treatment for depression — or sticking to your treatment, if you’ve already gotten help — can not only help you feel better emotionally, but it can help improve your brain health and cognitive well-being, too.
“The good news is that treatment can make a significant difference,” says Nelson. “Therapy, especially cognitive behavioral therapy (CBT), helps individuals develop strategies to address rumination and negative thinking patterns.”
If you suspect you have depression, know that seeking treatment early on can help avoid some of the effects on brain health before they happen, says Jackson. The potential signs and symptoms of depression, according to the National Institute of Mental Health, include:
- A sad, anxious, or empty mood that won’t go away
- Feeling hopeless
- Feeling irritable, frustrated, or restless
- Losing interest in things you used to enjoy
- Isolating yourself from friends and family
- Having trouble sleeping or sleeping too much
- Eating a lot less or a lot more than usual, leading to unintentional weight gain or loss
- Having trouble remembering things, concentrating, or making decisions
- Feeling aches, pains, digestive issues, or headaches that don’t have another medical explanation
- Losing your desire for sex or intimacy
- Using alcohol or drugs more frequently
- Having suicidal thoughts or behaviors
If you or a loved one is considering suicide, dial 988 to reach the Suicide and Crisis Lifeline, which is available 24 hours a day, seven days a week.