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Can Depression Affect Your Ability to Think?

Medically reviewed by Timothy J. Legg, PhD, CRNP on July 26, 2016Written by Holly Case

You might think that depression is just about being sad. You may not feel like doing the things that used to bring joy. You may not have much energy either. But if you frequently feel confused and distracted, don’t dismiss these symptoms. They’re a sign of major depressive disorder (MDD).

The link between MDD and cognitive processing

MDD is linked to problems with thinking and other cognitive processes. A study reported in the Journal of the Anxiety and Depression Association showed significant links between depression and cognitive function.

The following abilities are impaired in people with MDD:

  • attention
  • memory
  • ability to learn
  • decision-making
  • language processing
  • executive function (e.g., ability to multi-task or easily shift focus)

What causes cognitive problems in depression?

MDD is different than situational depression because it lasts longer. Many people with MDD have depression that lasts for extended periods. Having multiple episodes of prolonged depression is typical. These prolonged states of depression change parts of the brain and how they function.

Areas of the brain control how we respond to situations around us. Research suggests there’s a connection between damage to certain regions of the brain and an inability to cope with tasks. The same brain changes made people more likely to ruminate over things they’ve said or done.

High insulin levels are also linked to depression. People with type 2 diabetes are more likely to show problems with cognitive processing and memory. People who have multiple episodes of MDD over their lifetimes are also more likely to develop Alzheimer’s disease. It’s clear that depression and mental functioning go hand in hand. And there’s often a biological basis for both.

MDD and attention

Nearly everyone has some moments when they feel inattentive, but this is especially common for people with MDD. You may find it harder to follow along with the plot line of a complex movie. Maybe you frequently lose your place while reading. Conversations can be overwhelming because you’re prone to losing your train of thought.

People with MDD have more difficulty paying attention for long periods. They also find it more difficult to switch from one task to another. If you feel like you can’t focus, it’s not your fault.

MDD and memory loss

Do you find yourself forgetting the names of people you just met? Maybe you’re frequently missing the due dates for bills. Or you’re forgetting where you placed your glasses or keys. This is another common symptom of MDD.

A study in Behavioural Brain Health suggests that self-reported depression has a negative impact on memory. The study had participants fill out questionnaires that determined their level of depression. Then the participants had to view a series of objects on a computer screen. Upon being asked if they had seen the item before, most could distinguish between old and new items. But their results were different when shown something similar to what they had seen before. They believed they had already seen it. This shows that depressed people don’t have complete amnesia. Rather, they’re just missing details.

How MDD affects your ability to learn

Research shows that depression is linked to issues with working memory. Think of working memory as short-term storage on a computer. Information stored here must eventually make it into long-term storage. This takes place in part of the brain called the hippocampus. Chronic depression causes the hippocampus to shrink. This makes it more difficult for the brain to focus and learn.

If you’re trying to learn a new skill, such as a new language, you may find it incredibly challenging. Don’t give up or stress over it. Just know that it’s a part of having MDD.

Use of medication to treat cognitive dysfunction

The good news about the link between MDD and cognitive problems is that treatment may reverse the changes. Of course, the type of treatment may play a big role in their degree of success. Treatment isn’t always successful in all people, either. Those with many years of untreated MDD are less likely to respond well to antidepressants. Senior adults may also have age-related brain changes that make treatment less successful. Late-onset major depression also makes poor response to antidepressants more likely.

Studies suggest that certain antidepressants improve memory performance. However, the results aren’t always consistent. Antidepressants are also limited by which brain functions they can improve. Some studies found that certain antidepressants did not improve psychomotor speed or processing, both of which affect learning.

You may need to experiment with different drugs to find the right one. SNRI antidepressants such as duloxetine (Cymbalta) affect multiple parts of the brain. This may be helpful because many parts of the brain are involved in depression. A study in American Journal of Psychiatry reports that combinations of multiple medications may also be more likely to provide relief.

L-triiodothyronine (T3) may help people with treatment-resistant depression. It’s especially helpful when used with tricyclic antidepressants (TCAs) or monoamine oxidase inhibitors (MAOIs).

Stimulants such as methylphenidate (Ritalin) or D-amphetamine (Dexedrine) may also be beneficial. These stimulants are usually used to get a quick response and in combination with other antidepressants.

MDD can impact your ability to think, but a variety of treatments may help you live a healthier, more functional life.

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