Mental Illnesses are Brain Diseases

Written by Monte Nido & Affiliates East Coast Medical Director Dr. Molly McShane, MD, MPH

Molly McShane_PhD MPH_Chief of PsychiatryDr. McShane is a board certified psychiatrist and practices psychotherapy and medication management for a range of psychiatric conditions. Dr. McShane dives into the neurobiology and genetics of mental health disorders in this week’s blog post.

It is an exciting time in the world of brain and mental health research. Over the past few years, there has been an exponential increase in research findings in the neurobiology and genetics of mental health disorders. While we have known for decades that mental disorders are related to dysfunction in brain pathways, we are now able to say that mental illnesses are brain diseases.

Most diseases develop, progress and/or resolve due to a number of factors including biology, genetics, psychological co-morbidities and environmental exposures. Like most diseases, eating disorders typically occur in individuals with a genetic predisposition, meaning they born with genes inherited from their parents, which are associated with eating disorders. Data shows that 50 to 80 percent of the risk of developing an eating disorder is related to genetics. Clinically, we know this. It is very common for my patients to tell me they have family members with eating disorder histories. In fact, first degree relatives of patients with eating disorders are over eleven times more likely to have anorexia nervosa compared to controls. There are over forty genes involved in the regulation of eating disorder behaviors, motivation, reward, personality traits and emotions. The relationship between the genes and environment is complex. These genes may be turned on or off by environmental triggers. Of course, environment (exposure to social media that over-emphasize image, involvement in certain activities like dance, modeling or wrestling, etc.) can play a significant role in the development of an eating disorder.

Certain temperaments are associated with the development of eating disorders. While specific genes have not yet been identified with temperament, we do know that temperament traits are often constant throughout life, before, during and after experiencing an eating disorder. The temperament traits commonly seen in individuals with eating disorders include harm avoidance, perfectionism, neuroticism, compulsivity, dysphoric mood, low self-directedness, impulsivity, sensation seeking, lack of planning and lack of persistence. Individuals with eating disorders may experience one or more of these temperament traits throughout life, while the eating disorder symptoms often change over time. It can be helpful to address the management of temperament traits in therapy.

Brain research has revealed that neurochemistry is disrupted in individuals with eating disorders. Serotonin and dopamine are neurotransmitters that are involved in complex signaling pathways. These pathways are dysregulated in eating disorders, mood and anxiety disorders. Dopamine is involved in functions related to reward, pleasure, movement, compulsion and perseveration. Serotonin is involved in functions related to mood, memory processing, cognition and sleep. Considerable evidence suggests that altered serotonin and dopamine functions contribute to dysregulation of appetite, mood, impulse control and temperament in individuals with eating disorders. Restriction causes reduced plasma levels of tryptophan, the precursor to serotonin, which modulates serotonin activity and therefore symptoms of anxiety and depression. In individuals without eating disorders, dopamine is associated with a positive reinforcement effect in feeding. In other words, eating feels good.

In anorexia nervosa, dopamine dysregulation diminishes the reward effects of food, so that eating does not necessarily feel good. Data suggests low levels of dopamine receptors and weakened responsivity of dopamine is associated with increased eating and weight. We also know that appetite-regulating hormones, like leptin and ghrelin, may affect dopamine functioning. Leptin is an appetite suppressing chemical, and ghrelin stimulates the appetite. In patients with anorexia nervosa, ghrelin is abnormally low. In patients with binge eating, leptin is abnormally low. These findings help confirm that eating disorders are not due to “lack of will power”. There are chemical alterations in the brain that affect the development and persistence of eating disorder symptoms.

The more we as providers understand the biological basis of eating disorders, the better equipped we are to provide effective treatments. Based on new research in the field, novel medications are being studied that may help us better treat eating disorders. Psychiatric medications that target serotonin and dopamine pathways, such as SSRIs, can be very helpful in the treatment of eating disorders and co-morbid anxiety and mood disorders. Usually, the best treatment for eating disorders is a multidisciplinary approach involving a therapist specializing in eating disorders, a psychiatrist, nutritionist and primary care physician.

Content originally posted on October 5, 2017 at