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What is the Connection Between OCD and the Brain?

Micah Abraham, BSc
What is the Connection Between OCD and the Brain?

Though it is as yet unknown precisely why obsessive-compulsive disorder (OCD) occurs, many theories exist. Studies of the brains of those with OCD show certain activities that differ from the brains of people without OCD. Also, there are certain physical features present in the brains of people with OCD that lead scientists to believe that the structure of the brain itself may play a part in causing OCD.

This article will look at the different features of the brain that are thought to contribute to OCD behaviors.

The Brain Causes of OCD

Even though the brains of those with OCD do differ, it's not as simple as saying that your brain causes your disorder. Lifestyles and experiences still contribute to OCD symptoms, and the disorder itself can be reduced without even altering your brain. 

However, there is no denying that there are some theories about the differences between those with OCD and those without OCD. The following are some of the initial findings:

Serotonin Abnormalities

Insufficient serotonin levels in the brain and body are thought to be a major contributing factor to OCD. This is why medication for most anxiety disorders, including OCD, involves antidepressants known as selective serotonin reuptake inhibitors or SSRIs.

Serotonin is a chemical in the brain known as a neurotransmitter. Sufficient levels of serotonin allow for chemicals to travel effectively between brain cells or neurons, whereas insufficient levels prevent this from happening, causing mood fluctuations and stress. SSRIs increase your serotonin levels by limiting its reuptake by the neurons so that enough is available to keep the synapses firing and messages traveling smoothly within the brain.

In people with OCD, serotonin receptors are under stimulated due to limited serotonin production, leading to a decrease in serotonin receptors and, often, an increase in receptors for stress-related chemicals such as norepinephrine and cortisol. This combination may be contributing to an environment that changes brain function.

Genetic Mutation

In relation to serotonin abnormalities, studies have shown a possible link between a particular genetic mutation of the human serotonin transporter gene and OCD.

In one study, the transporter gene, hSERT, was found to be mutated in multiple families with no biological relation to one another.

People who develop OCD in childhood or young adulthood are particularly likely to have a parent or parents with the disorder. Due to the number of people with OCD whose parents have also been diagnosed, there is contention over whether this points to OCD as a hereditary disorder or to nurture rather than nature is a primary factor in the development of the disorder.

Grey Matter

The brains of people with OCD differ significantly from the brains of people with other anxiety disorders regarding their brain's' grey matter.

Grey matter is exactly what it sounds like: namely, grey-colored brain matter that is made up of neurons, or brain cells, and capillaries through which thoughts and chemicals travel. Grey matter occupies parts of the brain in charge of functions such as muscle control, sensory perception, speech, memory, and emotions.

People with OCD have an increased amount of grey matter between sections of the brain known as the bilateral lenticular nuclei and the caudate nuclei and less grey matter in other sections, including the bilateral dorsal medial frontal gyrus and the anterior cingulate gyrus. People with other anxiety disorders have the opposite abnormalities.

Why this difference is present in people with OCD has not been accounted for, but the consistency of the difference may support the theory that OCD is a biological trait.

Striatal Abnormality

The striatum is a part of the brain responsible for planning and movement coordination. Striatal abnormalities in mice have been shown to cause behaviors similar to OCD, such as excessive and compulsive grooming. It is suspected that striatal abnormalities in humans have much the same effect, and may be a key component in at least some cases of OCD.


In children, it has been proposed that PANDAS, also known as pediatric autoimmune neuropsychiatric disorders associated with streptococcal infections, or strep, for short, may be a contributing factor to eventual adult OCD. Other bacterial and viral infections that produce similar immunological responses have also been implicated in childhood-onset OCD.

The body's immunological responses to the infection, rather than the infection itself, are thought to be the cause of eventual OCD, though the reason for this is not well understood. The immunological response thought to be responsible for eventual OCD symptoms is the production of particular proteins that the body uses to fight the foreign bacteria.

OCD symptoms may begin either during or after a strep infection. While strep can be diagnosed if suspected by testing a throat swab ad treated via antibiotics, the best way to treat OCD symptoms in children is through cognitive behavioral therapy (CBT) and the use of SSRIs.

OCD as Evolution

How the brain is structured and functions may have to do with the theory posed by evolutionary psychologists that humans developed OCD behaviors as a survival mechanism. OCD type behaviors such as compulsive cleanliness and sensitivity to environmental irregularities may have provided early humans with evolutionary advantages. Evolutionary psychologists contend that people with OCD are simply people who inherit more of these behavioral brain traits than others.

Even if OCD behaviors were developed to help humans thrive and evolve as a species, individuals with this disorder will assert that OCD as a disorder does not help them personally to thrive or evolve, but instead keeps them stuck in their routines. Escaping OCD primarily involves getting your brain the help it needs, whether through therapy, medication, or healthy lifestyle choices that can affect the way your brain works for the better.

Healthy Ways to Change Your Brain

While the antidepressant medications SSRIs or serotonin reuptake inhibitors are frequently prescribed for increasing serotonin levels in the brain and body, you can also increase these levels by taking up the following healthy behaviors:

While the above activities can be valuable, they are still fairly basic. You still need a comprehensive option that will decrease your overall anxiety and help you control your obsessive-compulsive disorder. Remember, even though there may even be a genetic reason for OCD, your mind can adapt. Learn to cope with anxiety, and your OCD symptoms will decrease.

Article Resources
  1. Ozaki, N., D Goldman, W. H., Plotnicov, K., Greenberg, B. D., J Lappalainen, G. R., & Murphy, D. L. (2003). Serotonin transporter missense mutation associated with a complex neuropsychiatric phenotype. Molecular Psychiatry, Volume 8, 933-936. Molecular Psychiatry, Volume 8, 933-936.
  2. Welch, Jeffrey; et al, J; Rodriguiz, RM; Trotta, NC; Peca, J; Ding, JD; Feliciano, C; Chen, M et al. (August 2007). Cortico-striatal synaptic defects and OCD-like behaviours in Sapap3-mutant mice. Nature 448 (7156): 894-900. doi:10.1038/nature06104.
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