Depression

Does Being Depressed Make You More Likely to Dwell on Negative Memories?

September 30, 2019

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Persistent feelings of hopelessness, emptiness, guilt, and disinterest are among the core symptoms of depression. Given that negative emotions such as these are such a defining factor of the condition, it isn’t exactly inconceivable that those who suffer from depression might possess seemingly pessimistic tendencies. 

However, recent studies indicate that people with depression aren’t merely displaying a “glass-half-full” type of mentality. Instead, the researchers suggest that depression might cause a negative memory bias due to impairments in the brain’s structure. 

Keep reading to find out more about:

  • Physical changes that can occur in the brain due to depression
  • Negative memory bias and research linking it to depression
  • Treatment options for depression

How Does Depression Impact the Brain Physically?

Not only can depression impact the body physically—weight gain or loss, muscle pain, headaches, etc.—but it can also result in physical changes in the brain. These physical changes can include brain shrinkage, brain inflammation, oxygen restriction, and reduced functionality.

Map of the brain with functions
The brain is an extraordinarily complex organ, and researchers are still in the process of learning about it and the way it works. This means that when it comes to mental health conditions like depression, not much is known for certain. 

Brain Shrinkage

A recent study suggests that depression can cause certain areas of the brain to shrink. These areas include:

  • The hippocampus, which affects learning and memory
  • Thalamus, which affects sleep, consciousness, and alertness
  • Amygdala, which affects emotional processing
  • Frontal lobe, which affects problem solving and judgement
  • And prefrontal cortex, which affects decision-making and cognitive control

Because we still have so much to learn about depression (and the brain in general), researchers aren’t entirely sure about the areas of the brain that can shrink due to depression or the extent to which these areas can shrink. However, any region of the brain that loses volume is likely to suffer impaired function afterward. 

Brain Inflammation

Researchers have yet to determine whether depression causes brain inflammation or vice versa. That being said, brain inflammation is definitely associated with depression, and one study even found that people suffering from depression for over 10 years might have 30 percent more inflammation in their brains than those who have been depressed for a shorter period of time. 

Brain inflammation can cause brain cells to die, which can lead to decreased cognitive function and reduced neuroplasticity, affecting brain development, memory, learning, and mood. 

Oxygen Restriction

Again, it’s unclear which is the cause and which is the effect in the case of depression and oxygen restriction. Studies hypothesize that depression can cause changes in breathing, which in turn can reduce the levels of oxygen that are present in the body. This can lead to damaged brain cells and brain-cell death. 

Reduced Functionality

Memory, mood, attention, and executive function can all be reduced due to structural changes in the brain possibly caused by depression. According to Healthline, “Changes typically take a minimum of eight months to develop. The potential for persisting dysfunction in memory, executive function, attention, mood, and emotional regulation does exist after bouts of longer-lasting depression.” 

Negative Memory Bias

What is It?

Negative memory bias is the higher retention of negative information in memory as opposed to remembering more information that is positive or neutral. This bias also means an increased likelihood to ruminate on these negative memories rather than focusing on ones that evoke feelings of happiness. 

Diagram of the brain
Did you know that the hippocampus got its name because it resembles a seahorse? “Hippos” means “horse” in Greek, and “kampus” means “sea monster.” Image courtesy of Medical News Today

Research Connecting Negative Memory Bias and Depression

The hippocampus is a part of the brain that plays a major role in recollection and memory storage. Our brains record past experiences by encoding memories in clusters called engrams. Using calcium imaging, researchers are able to track engrams and analyze the patterns that correspond with the creation, processing, and retrieval of memories. 

In a study conducted at McGill University in Montreal, a research team used mice to observe the way that stress can affect the visitation of negative memories in the hippocampus. First, the researchers separated the mice into two groups: a stress-susceptible group and a stress-resilient group. The researchers then reactivated negative engrams in the mice’s hippocampi, hypothesizing that the stress-susceptible group would be more likely to exhibit depressive behavior. 

Psychology Today writes that “mice that retained more negative information were more likely to revisit the negative memory and behave in a depressed manner, whereas mice that retained less negative information were less likely to revisit the memory and behave in a depressed manner.” 

Does this mean that negative memory bias can be directly associated with depression? Not exactly—however, the results from the study indicate that the hippocampus might be partially responsible for some of the behaviors that accompany depression, as well as some of its symptoms. The researchers hope that their findings will lead to new therapeutic approaches to depression treatments that focus on inhibiting negative engrams. 

Treating Depression 

When it comes to treating depression, the most common approaches are psychotherapy and medication. Subjectivity and different emotional responses are part of what makes depression so difficult to effectively treat. This means that there are a variety of treatment options, even within each category of treatment. 

Psychotherapy

Talk therapy is typically the first treatment recommendation that patients with depression receive. Therapy comes in many different shapes and forms, and the version of therapy that is effective for one person might not yield the same positive results for another. Many therapists use a combination of techniques, but cognitive behavioral therapy (CBT) is one of the most common types of therapy that is used to treat depression. CBT focuses on modifying the cognitive processing of emotions in order to establish healthier thought patterns. 

Medication

If therapy alone proves inadequate to treating someone’s depression, the next course of action is usually medication. Again, there are many different kinds of antidepressants, and it’s difficult to know which kind will be most effective for which person. The most commonly prescribed family of antidepressants are selective-serotonin reuptake inhibitors (SSRIs). 

Treatment-Resistant Depression

Though psychotherapy and medication are beneficial for many people, sometimes they aren’t enough. As many as one third of patients have treatment-resistant depression, or depression that does not respond to treatment. Fortunately, there are additional treatment methods for depression, even if they are not as commonly known as therapy and antidepressants. 

One of these methods is transcranial magnetic stimulation (TMS), a psychiatric treatment that specializes in relieving symptoms of treatment-resistant depression. TMS uses magnetic pulses to stimulate mood centers in the brain that are thought to play a role in depression. Unlike electroconvulsive therapy, which is another way to treat treatment-resistant depression, TMS is non-invasive and does not require sedation, meaning that the patient is fully conscious throughout the treatment. 

TMS therapy has few side effects, and because it is non-pharmaceutical, most patients are able to continue taking antidepressants while going through treatment. In order for TMS to work, the therapy must be applied on a daily basis for an extended period of time, usually around six weeks. This enables the magnetic pulses to create substantial, lasting changes in the brain. Most sessions of TMS only last around 30 minutes, and afterward, the patient can resume daily activity immediately, as TMS does not affect cognition. 

Finding the right way to treat your depression can be a long, draining process. Hopefully, as the science around mental health continues to advance, we will get closer to a faster, more effective method of determining the best treatment process for each individual.

Bring Recovery Back into the Picture with TMS 

If you have treatment-resistant depression, you may be one of the many people who could benefit from TMS. As mentioned earlier, depression can cause physical changes to occur in the brain. Through magnetic stimulation, counteractive changes can be made, effectively “rewiring” the brain and reducing or eliminating depression symptoms. 

Again, there is still so much more that we do not know about the brain, its functions, and the conditions—like depression—that can affect the way a person thinks, feels, and acts. TMS could be the answer to the question that you’ve been asking yourself ever since you were first diagnosed with depression: “Why aren’t I getting better?” Ask your doctor about it today.

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