The Root Cause of mental illness: behavioral, genetic, and environmental
For some time, scientists have known the three primary factors that cause mental illness: behavioral, environmental, and genetic factors all contribute to the root cause of mental illness. In fact, the root cause of mental illness can be found at the intersection of genetics, environmental, and behavioral factors.
Mapping the genome and the ensuing research has made possible incredibly precise and targeted pharmacological approaches to treating mental illness with medication like Wellbutrin. The genes responsible for mental illness are being discovered, as well as treatments specifically targeting those genes. The search for the root cause of mental illness is beginning to come to an end.
What Is Mental Illness?
A majority of scientists view mental health illness as a communication problem between different neurotransmitters. Essentially, the brain’s nerves are not communicating the way they should because the neurotransmitter chemicals used to communicate are off. For example, people with depression have lower levels of serotonin.
Serotonin is a neurotransmitter that the brain uses to reward us and make us feel good. It does that by having neurons transmit serotonin back and forth throughout the brain. However, for people with depression, there is not enough serotonin produced. Medication used to treat this is called SSRI selective serotonin reuptake inhibitor, and it works by increasing the amount of serotonin available in between neurons in the brain.
There is currently no physiological diagnostic test for mental health disorders like depression, anxiety, or bipolar. However, some mental health illnesses like schizophrenia and OCD can be detected by brain scans. Research is currently underway attempting to identify depression or anxiety via blood markers. Such a breakthrough would be game-changing for diagnostic effectiveness.
Essentially, mental health illness is a disease of the brain- there are structural or functional differences in the brains of people who have mental health disorders and those that don’t.
One interesting correlation uncovered by researchers in recent years has to do with the comorbidity of mental illness or the presence of two or more mental health issues.
Studying the medical records of nearly 6 million Danish citizens, psychiatrist Oleguer Ripoll came to a surprising conclusion; any mental disorder predisposed a patient to every one of the other mental illnesses. It didn’t even matter how distinct the symptoms were[1]
In consideration of the preceding and other data from other research, scientists have begun redefining mental illness. Scientists and researchers are split into two camps; those that believe mental illness has two dimensions, and those that think there are multiple dimensions. The two-dimension camp views mental illness as being caused by a single genetic variation with the more refined details (like the specific type of mental health illness being decided by other genes). On the contrary, the multiple dimension camp disagrees, advocating for a complex interaction of genetic, environmental, and biological factors as the cause of mental illness.
No one denies the genetic factor or factors in mental health disorders; it’s the role of those factors which researchers are disputing. Below you can see the degree of heritability between psychiatric disorders. Notice the high degree of correlation between depression and anxiety- this means that these two disorders share more similar genes than other disorders. Same for Schizophrenia and Bipolar Disorder. This makes sense when one considers the similarities between these two disorders. For example, during a manic episode, Bipolar sufferers can develop delusions and hallucinations suggestive of schizophrenia. Depending on the severity of the manic episode, there can be significant psychotic features.
Citations
1. Plana-Ripoll, O. et al. JAMA Psychiatry 76, 259–270 (2019).