As humans, it is important that we are able to make memories of events in our lives to be able to survive. In the case of anxiety, particularly strong memories of traumatic or stressful events are made and the normal adaption and coping mechanisms to this memory aren’t working correctly. This leads to manifestation of anxiety and anxiety disorders like PTSD.
The hippocampus (shown in figure above) is part of the limbic system and is vital for storing memories. Thus, it plays a role in the brain response to stress. The dentate gyrus (DG) is a region of the hippocampus that specifically is involved in formation of episodic memories. Glucocorticoid hormones are responsible for enhancing memory formation and are released within the limbic system in response to events, where they bind to glucocorticoid receptors (GR). Within the DG, there is also a double histone mark (H3S10p-K14ac) that is responsible for opening up genes associated with memory formation for transcription.
Normally, GABA (an inhibitory neurotransmitter) is involved in regulating the responsiveness of the DG to stressful events and thus reducing anxiety. During stress, glutamate (an excitatory neurotransmitter) binds to its receptor in the DG and activates the NMDAr-ERK-MAPK pathway. Basically, binding of glutamate allows calcium ions to enter and activates molecules (MEK and ERK) to lead to gene transcription. GR works with the NMDAr-ERK-MAPK pathway to activate H3S10p-K14ac and allow gene transcription.
In people with anxiety, there is an increase of GR in the DG. There is also an increase in H3S10p-K14ac. Increased histone mark levels leads to increased transcription of genes like c-fos and erg-1. This leads to increased memory formation. There is also less GABA to regulate all of these processes associated with stress.
Exercise as a Treatment
Exercise is known to have many benefits for the human body. Of course, exercise improves a person’s physical health, but it may even improve mental health. Exercise results in more GABA receptors and GABA producing enzymes. This increase of GABA means there is more inhibition of the DG. This inhibition decreases the activation of the associated signaling pathways and consequent gene transcription. All around leading to lower levels of anxiety and possibly enhanced cognition.
Regular exercise may be beneficial for those with anxiety. Perhaps even as a prescription in co-treatment to classical pharmacological and behavioral therapies. Eventually, a person with anxiety may be able to use only exercise and behavioral therapies for treatment. This could extend to more mental health diseases and disorders than just anxiety, like depression.
So, if exercise has such well known benefits to overall physical health and the added potential benefits to mental health, why is there not more of a push for exercise in schools, college, and life. Many schools are removing or reducing physical education classes to focus more on academic classes. There is a general societal notion that we should exercise, but society also makes it difficult to do so. For college students, after a full day of classes they may feel like there’s not enough time for exercise with work, studying, and other responsibilities.
The concept of exercise also makes it intimidating. Exercise doesn’t have to mean an hour long hard work-out and being super fit. Simply being active, increasing the heart rate, for a short amount of time could provide the benefits. When dealing with the next stressor life throws out, go for a walk and get active to allow the brain to process the events in a healthy manner.
For more on anxiety and the brain visit: https://www.ncbi.nlm.nih.gov/pubmed/24478733