Common Risk Factors That Contribute To Both Mental Illness and Substance Abuse

It is not uncommon for individuals who live with mental illness to develop a drug addiction or vice versa—for those with a drug addiction to receive a mental illness diagnosis. In fact, findings reveal that as many as one in four individuals who have a serious mental illness also live with a substance abuse disorder. In youths, that number is much higher. Though there are fewer studies on the correlation between youth SUD and SMI, research suggests that over 60 percent of adolescents in community-based substance abuse treatment programs also meet the diagnostic criteria for mental illness.  

This area of study is of particular interest to researchers as though there seems to be comorbidity between substance abuse and mental illness, it's difficult for them to pinpoint which came first: the SUD or the SMI. It's a classic case of the chicken or the egg phenomenon. What confounds researchers even more is the fact that the disorders seem to share many of the same risk factors. You can explore those risk factors below.

Genetic Vulnerabilities

According to the National Institute on Drug Abuse, mental illness and substance abuse share several major risk factors. Genetic vulnerabilities are the first one. According to the findings, approximately 40 to 60 percent of a person's vulnerability to substance abuse disorder can be attributed to his or her genes. One active study on comorbidity further shows that once a person develops either SUD or SMI, he or she has an even greater risk for developing a second disorder.

Most of a person's predisposition for experience either or both SUD or SMI hinges on the complex interactions between his or her genetics and environmental influences. For instance, findings reveal that teens who smoke marijuana frequently are at a higher risk of developing psychosis in adulthood. This particularly true among individuals who carry a certain gene variant.

Epigenetic Influences

Epigenetic influences are those that alter how the body's cells read or act on genetic information. Epigenetic factors such as trauma, chronic stress, or drug exposure have the ability to induce changes to otherwise normal gene expression. Depending on the nature of the change, these factors may ultimately alter the way neural circuits function, which can impact behavior.

Environmental Influences

As the above point suggests, environmental influences may play a major role in the development of a serious mental illness and substance abuse. Though there are hundreds of environmental factors that can influence a person's behavior, including the weather, peer groups, and career, the National Institute on Drug Abuse suggests that the biggest players in both SMI and SUD are chronic stress, adverse childhood experiences, and early trauma.

Brain Region Involvement

When examining the areas of the brain that show changes in activity in those with SUD or SMI, researchers note that many of the same areas seem to be affected. For instance, the areas of the brain that regulate decision making, reward, impulse control, and emotions happen to be the same regions that are afflicted by depression, schizophrenia, mood disorders, substance abuse disorder, and other psychiatric disorders. Moreover, multiple neurotransmitter systems have been linked to both SUD and SMI, including but not limited to serotonin, dopamine, GABA, glutamate, and norepinephrine.

Several studies on both mental health and substance abuse reveal several similarities between the two disorders. However, as of yet, there is no clear direct connection.