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Depression and the Brain

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  • Recurring depressive episodes reduce the size of your hippocampus, a brain area involved in forming emotions and memory; a smaller hippocampus equates to a loss of emotional and behavioral function
  • Chronic inflammation may be the most important underlying risk factor for depression, and virtually all effective treatments for depression also address inflammation
  • Key treatment strategies include trading processed foods for real food, with an emphasis on fermented foods to optimize your gut flora, exercise, and optimizing your vitamin D by getting appropriate sun exposure
 

How Depression Affects Your Brain Structure

July 30, 2015 | 575,533 views
| Available in EspañolDisponible en Español

By Dr. Mercola

That depression can take a toll on your physical health is pretty well-recognized. Recent research has also found that it can actually cause changes in your brain.

Specifically, recurring depressive episodes reduce the size of your hippocampus — an area of your brain involved in forming emotions and memory — stressing the importance of early intervention, especially among teenagers.

Your memory isn't only restricted to remembering dates and passwords; it also plays an important role in developing and maintaining your sense of self.

When your hippocampus shrinks, it's not just your rote memory that is affected, behaviors associated with your sense of self are also altered, and a smaller hippocampus equates to a general loss of emotional and behavioral function.

The good news is the damage is likely reversible, but to do that, you have to actually do something about your situation.

Chronic Depression Can Damage Your Brain

Using brain magnetic resonance imaging (MRI) data of nearly 8,930 people from around the world, an international team of researchers found that those who suffered recurring bouts of depression also had a smaller hippocampus.1,2,3

This applied to about 65 percent of all depressed participants.  Those who were experiencing their first depressive episode did not show evidence of shrinkage, suggesting it's the repetitive recurrence that causes the hippocampus to shrink.

Those who showed hippocampal shrinkage also reported getting depressed earlier than the others, typically before the age of 21.

Previous studies have noted that depressed people tend to have a smaller hippocampus, but it was not known whether this was a predisposing factor, or a result of the illness.

This study reveals the answer: Depression comes first; the brain damage follows...  According to co-author Professor Ian Hickie:4

"[The] more episodes of depression a person had, the greater the reduction in hippocampus size. So recurrent or persistent depression does more harm to the hippocampus the more you leave it untreated.

This largely settles the question of what comes first: the smaller hippocampus or the depression? The damage to the brain comes from recurrent illness...

Other studies have demonstrated reversibility, and the hippocampus is one of the unique areas of the brain that rapidly generates new connections between cells, and what are lost here are connections between cells rather than the cells themselves.

Treating depression effectively does not just mean medicines. If you are unemployed, for example, and then sit in a room doing nothing as a result, this can shrink the hippocampus. So social interventions are just as important, and treatments such as fish oils are also thought to be neuro-protective."

The Inflammatory Roots of Depression

Contrary to popular belief, depression is not likely caused by unbalanced brain chemicals; however there are a number of other biological factors that appear to be highly significant. Chronic inflammation is one such factor.5

Scientists have also found that your mental health can be adversely impacted by factors such as vitamin D deficiency and/or unbalanced gut flora — both of which, incidentally, play a role in keeping inflammation in check, which is really what the remedy to depression is all about.

As discussed in an article by Dr. Kelly Brogan, depressive symptoms can be viewed as downstream manifestations of inflammation.

"The source itself may be singularly or multiply-focused as stress, dietary and toxic exposures, and infection... [I]nflammation appears to be a highly relevant determinant of depressive symptoms such as flat mood, slowed thinking, avoidance, alterations in perception, and metabolic changes,"6 she writes.

Certain biomarkers, such as cytokines in your blood and inflammatory messengers like CRP, IL-1, IL-6, and TNF-alpha, show promise as potential new diagnostic tools, as they're "predictive7 and linearly8 correlative" with depression.

For example, researchers have found that melancholic depression, bipolar disorder, and postpartum depression are associated with elevated levels of cytokines in combination with decreased cortisol sensitivity (cortisol is both a stress hormone and a buffer against inflammation).9

As explained by Dr. Brogan:

"Once triggered in the body, these inflammatory agents transfer information to the nervous system, typically through stimulation of major nerves such as the vagus, which connects10 the gut and brain. 

Specialized cells called microglia in the brain represent the brain's immune hubs and are activated in inflammatory states.

In activated microglia, an enzyme called IDO (indoleamine 2 3-dioxygenase) has been shown11 to direct tryptophan away from the production of serotonin and melatonin and towards the production of an NMDA agonist called quinolinic acid that may be responsible for symptoms of anxiety and agitation.

These are just some of the changes that may conspire to let your brain in on what your body may know is wrong."

Sugar Is One of the Most Inflammatory Ingredients in Your Diet

It's virtually impossible to address inflammation without noting the role of sugar, found in ample supply in most processed foods.

Besides promoting chronic inflammation, refined sugar intake can also exert a toxic effect by contributing to insulin and leptin resistance and impaired signaling, which play a significant role in your mental health.

Sugar also suppresses activity of a key growth hormone called BDNF (brain derived neurotrophic factor), which promotes healthy brain neurons. BDNF levels are critically low in both depression and schizophrenia, which animal models suggest might actually be causative.

In 2004, the British psychiatric researcher Malcolm Peet published a provocative cross-cultural analysis of the relationship between diet and mental illness.12 His primary finding was a strong link between high sugar consumption and the risk of both depression and schizophrenia.

Another study13 published in 2007 found that inflammation may be more than just another risk factor for depression. It may in fact be the risk factor that underlies all others. According to the researchers:

"The old paradigm described inflammation as simply one of many risk factors for depression. The new paradigm is based on more recent research that has indicated that physical and psychological stressors increase inflammation.

These recent studies constitute an important shift in the depression paradigm: inflammation is not simply a risk factor; it is the risk factor that underlies all the others.

Moreover, inflammation explains why psychosocial, behavioral and physical risk factors increase the risk of depression. This is true for depression in general and for postpartum depression in particular."

Eating Real Food May Be Key for Successful Treatment of Depression

The evidence clearly indicates that your diet plays a key role in your mental health, for better or worse. So if you're struggling with depression, mood swings, or feel yourself sliding into "the blues," I strongly advise you to look at what you're eating. The key is to eat real food, ideally organic (to avoid chemical exposures) and locally grown (for maximum freshness).

Also make sure to eat plenty of traditionally cultured and fermented foods, which will help nourish beneficial bacteria in your gut. Good examples include fermented vegetables of all kinds, including sauerkraut and kimchi, kombucha (a fermented drink), as well as fiber-rich prebiotic foods like jicama (Mexican yam).

Optimizing your gut flora appears to be absolutely crucial for good mental health, which is understandable when you consider that gut bacteria actually manufacture neurochemicals such as dopamine and serotonin, along with vitamins that are important for brain health. In fact, you have a greater concentration of serotonin in your gut than in your brain.

I recommend avoiding all types of processed foods, including certified organic ones, as processed foods are no longer "alive." What you're looking for is whole, unadulterated foods, with which to cook from scratch (or eat raw). Processed foods are simply loaded with ingredients known to alter your gut flora and promote inflammation, thereby inviting depression. This includes:

Added sugar and high fructose corn syrup

Genetically engineered (GE) ingredients (primarily corn, soy, and sugar beets) which, besides their own unknown health risks, also tend to be heavily contaminated with glyphosate—a Class 2A carcinogen that can also damage your gut microbiome and has been linked to antibiotic-resistance. Most conventional (non-GE) wheat is also treated with toxic glyphosate prior to harvesting.

By altering the balance of your gut flora, pesticides and herbicides also disrupt the production of essential amino acids like tryptophan, a serotonin precursor, and promote production of p-cresol, a compound that interferes with metabolism of other environmental chemicals, thereby increasing your vulnerability to their toxic effects.

Artificial sweeteners, along with thousands of food additives, most of which have never been tested for safety

Chemicals in the food packaging, such as bisphenol-A (BPA), bisphenol-S (BPS), and phthalates, which can migrate into the food

Trans fats

Exercise Effectively Combats Depression and Helps Rebuild Your Hippocampus

Recent research has shown clear links between inactivity and depression. Women who sat for more than seven hours a day were found to have a 47 percent higher risk of depression than women who sat for four hours or less per day. Those who didn't participate in any physical activity at all had a 99 percent higher risk of developing depression than women who exercised. Indeed, exercise is perhaps one of the most effective yet underutilized treatments for depression.

Studies have shown its efficiency typically surpasses that of antidepressant drugs. One of the ways exercise promotes mental health is by normalizing insulin resistance and boosting natural "feel good" hormones and neurotransmitters associated with mood control, including endorphins, serotonin, dopamine, glutamate, and GABA. 

It also helps rid your body of stress chemicals that can lead to depression, and while depression can shrink your hippocampus, exercise has been shown to increase the volume of gray matter in the hippocampal region of the brain. It also promotes neurogenesis, i.e. your brain's ability to adapt and grow new brain cells. While sugar suppresses brain derived neurotrophic factor (BDNF), thereby raising your risk of depression, exercise boosts it. 

Exercise initially stimulates the production of a protein called FNDC5, which in turn triggers the production of BDNF. BDNF is a remarkable rejuvenator in several respects. In your brain, it not only preserves existing brain cells, it also activates brain stem cells to convert into new neurons, and effectively makes your brain grow larger. Research14 confirming this includes a study by Kirk Erickson, PhD, in which seniors aged 60 to 80 who walked 30 to 45 minutes, three days per week for one year, increased the volume of their hippocampus by two percent.

Meditation Also Alters Your Brain in Beneficial Ways

Meditation is another underutilized tool to optimize mental health. Not only is it helpful for stress relief and gaining greater self awareness (if not a more spiritual perspective of life's ups and downs), it too has been shown to alter the structures of your brain for the better. As reported by Forbes:15

"The practice appears to have an amazing variety of neurological benefits – from changes in grey matter volume to reduced activity in the 'me' centers of the brain to enhanced connectivity between brain regions...

Skeptics, of course, may ask what good are a few brain changes if the psychological effects aren't simultaneously being illustrated? Luckily, there's good evidence for those as well, with studies reporting that meditation helps relieve our subjective levels of anxiety and depression, and improve attention, concentration, and overall psychological well-being."

With regards to depression specifically, a 2014 meta analysis16 of 47 studies concluded that mindfulness meditation can be helpful. While the overall effect size17 was "moderate" at 0.3, Forbes rightfully points out that this is identical to the effect size for antidepressants, which is also 0.3, and the go-to solution in most cases of depression. Like exercise, mindfulness meditation has also been shown to increase cortical thickness in the hippocampus, and brain areas involved in the regulation of emotions and self-referential thought processes.18

Shrinkage of the amygdala has also been noted. In this case, less cell volume in a brain center can be a blessing, as the amygdala controls the subjective perception of fear, anxiety, and stress.

People suffering with anxiety disorders tend to produce too much serotonin in the amygdala, which is why serotonin-boosting drugs like SSRIs can worsen depression and anxiety in some people. Previous studies have also revealed that increased nerve activity in the amygdala is part of the underlying mechanism that produces anxiety. Basically, those with anxiety disorders have an over-active fear center, and meditation may help dampen this over-activity.

Key Strategies to Overcome Depression

Two key strategies for overcoming depression have already been addressed above: diet (trading in the processed foods for real food, with an emphasis on fermented foods to optimize your gut flora), and exercise. Optimizing your vitamin D level by getting appropriate sun exposure (or taking a vitamin D3 supplement with vitamin K2) is another key strategy not to be overlooked. In one previous study, people with the lowest levels of vitamin D were 11 times more prone to be depressed than those who had normal levels.

Considering the fact that vitamin D deficiency is typically the norm rather than the exception, and has been implicated in both psychiatric and neurological disorders, getting your vitamin D level checked and addressing any deficiency is a crucial step.

There's no doubt in my mind that if you fail to address the root of your depression, you could be left floundering and struggling with ineffective and potentially toxic band-aids for a long time. Your diet does play a large part in your mental health, so please address the impact processed foods might be having.

Also be sure to support optimal brain functioning with essential fats. This includes healthy saturated fats like avocados, butter made from raw grass-fed organic milk, raw dairy, organic pastured egg yolks, coconuts and coconut oil, unheated organic nut oils, raw nuts, and grass-fed meats. I also recommend supplementing your diet with a high-quality, animal-based omega-3 fat, like krill oil. This may be the single most important nutrient to battle depression.

Last but not least, add some effective stress-busting strategies to your toolbox. Ultimately, depression is a sign that your body and your life are out of balance. One way to return balance to your life is by addressing stress. Meditation can be helpful, as discussed above. When weather permits, get outside for a walk. But in addition to that, I also recommend using a system that can help you address emotional issues that you may not even be consciously aware of.

For this, my favorite is Emotional Freedom Technique (EFT). Recent research has shown that EFT significantly increases positive emotions, such as hope and enjoyment, and decreases negative emotional states.  EFT is particularly powerful for treating stress and anxiety because it specifically targets your amygdala and hippocampus, which are the parts of your brain that help you decide whether or not something is a threat.19,20

Although you can learn the basics of EFT on your own, if you have a serious mental disorder or depression, I highly recommend consulting a qualified EFT practitioner.21 For serious or complex issue you need a qualified health care professional that is trained in EFT to help guide you through the process, as it typically takes years of training to develop the skill to tap on and relieve deep-seated, significant issues.

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