People who have obsessive compulsive disorder (OCD) experience intrusive thoughts, fears and/or urges, called obsessions, which are related to cleanliness, symmetry, order or contamination. Someone with this disorder may spend several hours of each day performing repetitive compulsive behaviors such as checking, cleaning, washing and counting to reduce their anxiety. Although many people with OCD attempt to ignore their obsessions and compulsions, they may have much difficulty controlling them or stopping them from occurring.
According to the National Institutes of Health (NIH), researchers have uncovered different genetic factors, structural and functional brain abnormalities (e.g., abnormal regulation of neurotransmitters such as serotonin, glutamate and dopamine) and other environmental factors, including stress and childhood exposure to the streptococcal infection that can increase a person’s risk for developing symptoms of OCD. However, the underlying molecular mechanisms that influence behaviors associated with OCD have yet to be identified.
Role of glutamate in OCD
Currently, the main treatments available to people with this disorder are psychotherapy (i.e., talk therapy) and medications, including antidepressants and antipsychotics. Reduced amounts of serotonin, a brain chemical (neurotransmitter) that plays a role in mood, anxiety, sleep, appetite and other important functions, have been found in individuals who have OCD. As such, antidepressants including selective serotonin reuptake inhibitors (SSRIs) have been used for treating patients with OCD to change the levels of serotonin in the brain.
Many people show significant improvement with antidepressants such as selective serotonin reuptake inhibitors (SSRIs). However, there is a need for a more effective treatment option for individuals who have OCD.
Researchers have also observed abnormalities in the neurotransmitters glutamate and dopamine in individuals who have OCD. The mechanisms that control these brain chemicals have also been studied. Glutamate, the major excitatory neurotransmitter in the spinal cord and brain, plays an important role in learning, memory and neural development, which are regulated by two different types of receptors: ionotropic and metabotropic. Recent research suggests that targeting the receptors for glutamate may be effective for reducing the symptoms of OCD.
Targeting mGluR5 signaling to reduce OCD-like behaviors in mice
A new study by Nicole Calakos, M.D., Ph.D., an associate professor of neurology at Duke University Medical Center, and her colleagues, suggested that metabotropic glutamate receptor (mGluR5) signaling may be the underlying mechanism responsible for the behaviors associated with OCD. The researchers found that having too much signaling of this mGluR5 receptor could produce behaviors associated with OCD.
The researchers treated Sapap3 knockout (KO) mice, which “demonstrate several OCD-like phenotypes, including increased striatal activity, increased anxiety-like behaviors and excessive and pathologic self-grooming that persists despite causing harmful facial lesions.” In other words, the KO mice exhibit behaviors and neural mechanisms similar to those observed in humans with OCD.
By using an mGluR5 antagonist to block the ability of glutamate to bind to the receptors, the researchers were able to inhibit the OCD-like behaviors in the KO mice. The results of this study suggested that inhibiting the activity of mGluR5 could be a potential mechanism to target when developing new medications for the treatment of OCD to help them manage their obsessions and compulsions.
Sovereign Health offers comprehensive treatment programs to patients with mental health conditions such as OCD and anxiety disorders as well as substance use disorders and co-occurring disorders. For more information about the behavioral health treatment services offered at Sovereign Health, please call our 24/7 helpline.
About the author
Amanda Habermann is a staff writer for Sovereign Health. A graduate of California Lutheran University, she received her M.S. in clinical psychology with an emphasis on psychiatric rehabilitation. Her master’s thesis was written on “The effect of parental codependency on elementary school children’s social and emotional development,” and her research has been accepted for poster presentations at the Western Psychological Association. She brings to the team her extensive clinical background and skills in psychological testing and assessment, clinical diagnosis, research and treatment, and recovery techniques for patients with mental illness. She is a passionate researcher and enjoys staying up to date on the newest topics in the field. For more information and other inquiries about this article, contact the author at firstname.lastname@example.org.