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Stress, Depression, Addiction and Your Brain

May 5 2021
9 min read
Woman looking off to the side with a slight smile.

Your emotional state, as well as your current mental health, can affect your memory and attention now and throughout your future.

In fact, a brain that is not taxed by stress, depression or addictive behaviors can continue to grow and develop as we get older.

This article is adapted from 30 Days to a Better Brain, by Richard Carmona, M.D., M.P.H., F.A.C.S., president of the Canyon Ranch Institute and a former Surgeon General of the United States.

The connection between retaining memories, neurogenesis (the birth of new brain cells) and mood is quite clear. Memories are built and stored in the brain’s temporal lobes and the hippocampus, areas that are intimately linked to emotion and mood. The amygdala is where we store powerful emotions such as disgust and fright and is connected to memory areas where we interpret faces and emotional expression. Another area, called the anterior cingulate cortex, is where we analyze an incoming stimulus for emotional content. This is the area responsible for mapping out past memories and making predictions based on them.

By utilizing these neighboring regions at the same time, the brain is constantly connecting memory, mood and emotions as it cross-references them so we can make new decisions.
Let’s take a look at the way mood, emotions and mental health can take a toll on your brain.


We know that stress negatively affects the brain. At Canyon Ranch we see stressed-out people who are operating in survival mode. They feel frenetic and exhausted. They can’t think clearly because they don’t have the resources; the brain’s response to stress is to shut down everything except those systems that are going to keep you alive.

Prolonged, chronic stress also prompts the brain to begin to compensate with another survival mechanism. During periods of chronic stress, the neurotransmitters, or brain chemicals, that are vital for healthy cognitive function become depleted. These include the chemicals that power your brain, such as dopamine, epinephrine and acetylcholine, the neurotransmitter that’s most responsible for attention and memory. To make up for the loss of brainpower, the pituitary gland inside the brain signals the adrenal gland, located above the kidneys, to release a replacement hormone known as cortisol. This hormone is produced in greater quantities when we are stressed, and provides the energy our brain needs to continue to function.

The good news is that our brains are well-suited to manage small doses of cortisol; however, elevated levels of cortisol overstimulate the brain, and this overstimulation eventually depletes you emotionally, physically and intellectually. Worse, too much cortisol can change the physical structure of the brain, causing the hippocampus to shrink. This is a problem because the hippocampus is the part of the brain most important for short-term memory. In order to maintain your ability to create and store memories, it’s vitally important to manage your stress and cortisol levels.

Cortisol causes dendrites to retract. Dendrites are the projections that allow neurons to communicate quickly with other brain cells. When you retract those dendrites, retrieving stored information becomes harder. High levels of cortisol also cause a certain degree of cell death because when you’re chronically stimulated, you’re releasing a large amount of the amino acid glutamine. Glutamine causes the cells to open up and allow in a rush of calcium, which helps the chemical message move from one cell to the next. But if a cell gets too much calcium, it may die. This is why the creation of new neuronal connections takes place to a lesser extent when you are under stress.


Our personalities and worldviews absolutely influence the ways our brains age. People who are more curious about life and who handle stress well are going to be able to maintain better brain health as compared with those who are not interested in learning new things, who are pessimistic and cynical and get angry all the time and who are loaded with stress.

We know this is true because depression is also linked to the overproduction of cortisol. In one 2003 study published in the American Journal of Psychiatry, the volume of the hippocampus was less in people who had depression than in people of the same age and the same health who didn’t have depression. However, when the depression was treated, whether with medications or psychotherapy, researchers actually saw a rebound in terms of the hippocampal volume, suggesting there is some degree of reversibility. The findings also showed that antidepressants, when used appropriately, may have a neuroprotective effect.

We also know that stressful events promote neurochemical changes that may be involved in the provocation of depression. What’s more, people who are profoundly depressed act as if they have dementia.

When we are depressed, there’s an overactivation of certain brain regions, such as the ones responsible for worrying, and an underactivation of others, such as the hippocampus and certain parts of the prefrontal cortex, which can cause the symptoms of dementia.

People with low mood may find it hard to think, and the deeper a person is in depression, the harder it is to think clearly. This condition then affects memory, attention and judgment. If people suffer from obsessive-compulsive behavior or thoughts, they may fixate on one topic and not pay attention to the rest of what is going on around them. Or they start having intrusive negative thoughts.

It’s difficult to determine if depression causes the symptoms of dementia, or if dementia causes depression, in older adults. Some become depressed when they lose brain function, or when they realize that their lives are more limited. Neurologists and psychologists agree that enhancing mood is a good initial step, regardless of which condition came first. By treating the depression, they find that cognitive function can get better.


The brain creates habits and addictions in a process that involves a three-step activity loop called the dopamine reward system, which releases the “feel-good” brain chemical dopamine in anticipation of exposure to pleasure. However, when we develop addictive behaviors, they actually make us less happy. Frequent exposure to addictive behaviors and substances decreases the number of dopamine receptors in the brain. With fewer receptors, lower levels of dopamine are activated, leaving more intense cravings and increased stress. Over time, it takes a larger exposure of whatever you are addicted to in order to reach the level of reward.

The catch is that the brain can’t keep up with demand. Instead, it strives to reach homeostasis, or balance, so that each time you are exposed to the addictive substance or behavior, the brain releases less dopamine, not more. When this happens, the euphoric feeling doesn’t come back at all. Yet many people will still continue to drink or smoke in the hope that it will return.

What’s more, many addictive substances directly cause cognitive failures. Alcoholics are known to experience blackouts, which are memory gaps that occur even when they are conscious. Both illegal street drugs and prescription pain medications can tamper with memory, cloud judgment, limit attention and increase forgetfulness.

The long-term damage of drug and alcohol addiction is related to cognitive decline as it both kills off brain cells and disrupts brain chemical production, which is directly linked to dementia.

Surprisingly, it doesn’t take much to create damage: In a 2011 study from Northumbria University, people who smoked cigarettes only on weekends caused as much damage to their memory as those who smoked on a daily basis.

Some people will try to self-medicate their low mood or anxiety with alcohol, drugs or food. Many come home from a hard day of work and pour themselves a few drinks in order to release the tension of the day. Unfortunately, the strategy they’ve chosen may offer temporary relief, but can cause bigger health problems down the road, such as obesity, liver disease and cognitive decline. Addiction is serious, and it can require professional help. When you develop addictive behaviors, you have to identify them so you can stop them. If you believe you have an addiction, talk to your doctor to find the right programs that address your particular health issues.

Indeed, managing your mood in healthy ways is a key prescription for a healthy brain.

A headshot of Chief of Health Innovations, Richard Carmona.

About the Expert

A headshot of Chief of Health Innovations, Richard Carmona.

Richard Carmona

MD, MPH, FACS, Chief of Health Innovation

From days of homelessness as a child, Dr. Richard Carmona worked his way up to serving as 17th U.S. Surgeon General (2002 – 2006). He’s a renowned integrative medicine physician, trauma surgeon, and global public health leader with military service and law enforcement experience. His long-standing leadership role and personal relationship with Canyon Ranch reflect a shared vision to promote healthy living.

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