Drug use disorders and mental illnesses go hand-in-hand as people addicted to drugs have two-times higher risk of developing mood and anxiety disorders as compared to general people, and vice-versa. According to the 2019 National Survey on Drug Use and Health (NSDUH), 24.5 percent (or 61.2 million adults) aged 18 or older experienced either any mental illness (AMI) or a substance use disorder (SUD) in the past year. Moreover, 16.8 percent (or 42 million people) suffered an AMI but not an SUD. The survey also reported a 3.9 percent (or 9.7 million people) incidence of an SUD but not AMI while 3.8 percent (or 9.5 million people) were found struggling with both an AMI and an SUD.
Such a high co-prevalence of AMI and SUD forces one to think is both these things are inter-related and if so, then why?
Co-occurrence: A coincidence or more
The high incidence of co-occurring substance use disorders and mental illnesses is independent of a causal association between the two. Moreover, it does not indicate any particular sequence in the onset of the problem, simply because multiple factors may contribute to SUDs and AMI, with most of them being independent of each other.
For example, it is important to see if symptoms have progressed to a specific level (per DSM) to confirm the diagnosis for any mental disorder. However, subclinical symptoms may also lead to drug use. Although it is always difficult to tell which comes first between AMI and SUDs. However. three possibilities seem to exist.
- Drug use may lead to mental illness: Drug or drugs of use may be responsible for causing one or more symptoms of a mental illness in the user. The evidence supporting the possibility comes from the known association between increased risk of psychosis and marijuana in some users.
- Mental illness leading to drug use: Researchers have been talking about the possible role of mental illnesses in causing drug use. Individuals reporting overt, mild, or even subclinical mental disorders are vulnerable to drug use as self-medication. Slowly, as the person feels more empowered with the use of the drug, they become dependent on it, leading to an addiction.
- Overlapping factors: There are certain factors including genetic vulnerabilities, brain deficits, and/or early exposure to stress or trauma, which may cause both AMI and SUDs.
All these three scenarios may express themselves (in different degrees for different individuals) in making a case for a co-occurring AMI and SUD.
Exploring common factors
Genetics has a role to play in both, an AMI and a SUD. Genetic factors can be a significant common link between these two conditions, which is known to contribute to the development of both addiction and other mental illnesses. According to researchers, genetics make a 40-60 percent contribution to one’s vulnerability to addiction. At the same time, genes can also act indirectly contributing to the development of SUD by altering an individual’s response to stress or one’s tendency to develop risk-taking and novelty-seeking behaviors.
Similar brain regions are involved. It may be more than a coincidence that in the case of both SUD and AMI, the same brain regions are affected. For example, addictive substances and mental illnesses such as depression and other psychiatric disorders affect dopamine, a chemical that carries messages from one neuron to another.
This overlap of brain areas affected by AMI and SUDs may indicate a possibility of some brain changes that may be caused from any one of these and affecting the other.
A report published in the National Institute of Drug Abuse (NIDA) suggests that the development of a mental disorder and subsequent changes in brain activity tend to increase one’s susceptibility to using substances by reducing awareness of their negative effects, amplifying their positive effects, or relieving the unpleasant effects caused due to the mental disorder.
Getting mentally healthy is all about timely treatment
Different behavioral therapies have been found effective in treating comorbid conditions. However, it is important to consider other associated factors like patients’ age and specific drug used among other things while going ahead with the planned treatment.