Previously, I reviewed some ways that our brains become inflamed. Today, I will connect inflammation with depression and then as promised will explain why methylated folate can help. Inflammatory markers such as C-reactive protein (CRP) are often elevated in depressed patients. We see an increased incidence of depression in stressed individuals, those with medical illness or obesity, those on highly processed diets and the sleep deprived. Each of these conditions are strongly associated with inflammation. Some folks are apparently resistant to this effect and will be inflamed but not depressed. We now know that multiple mechanisms work together to cause depression with inflammation being one of them. Following are some of the ways that inflammation contributes to depression.
1. Neurotransmitters which modulate mood such as serotonin, norepinephrine and dopamine are depleted in the inflamed brain.
2. Substances which help the brain rewire itself, such as brain derived neurotrophic factor (BDNF), are depleted by inflammation. This “neuroplasticity” is crucial in maintaining a healthy mood.
3. The neuroendocrine (brain hormone) system is affected by inflammation with cortisol often being chronically elevated. Elevated cortisol is associated with depression.
4. Specific areas of the brain such as the anterior cingulate and the basal ganglia when inflamed lead directly to depressed symptoms.
These are some of the well understood mechanisms which explain the connection between depression and inflammation. Please understand that I am not trying to say that depression is always primarily caused by changes in brain chemistry. I am simply presenting the relevant physiology so that we can later appreciate the positive effects of lifestyle changes on depression as well as the benefits of a particular supplement.