Understanding the Genetics of Mental Illness

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Nearly one in five American adults experience, or will experience, some kind of mental health disorder during their lifetime. With half of all cases beginning by the age of 14, up to 75% of mental illness cases will be fully developed by the age of 24. In 2017, about 46 million Americans were reported to have some kind of mental illness. This includes all levels of severity, from mild to serious mental illnesses. Mental illness is not only very common in America; it is also a global epidemic.

The most common view about mental illness is that it is often a mixture of genetic disposition and environmental factors. Although there are no specific known genes for mental illness, and a person may not automatically carry a gene that directly causes mental illness, one can be predisposed. Here are some things you should know about genetics and mental health.

Genetic Predisposition

Researchers have yet to find a specific gene that is directly linked to certain forms of mental illnesses. Genetic markers may exist, but not always. A growing body of research has found that certain gene variations are associated with mental disorders. This research shows that you are more likely to have certain mental illnesses if members of your family have them. This is called genetic predisposition.

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Family History

Your family history is one of the best clues regarding your risk of developing mental disorders and many other common illnesses. Having a close family member or relative with a mental illness means you are likely at a higher risk than a person with no family history of mental illnesses. It is also important to note that even if there is no family history of mental health conditions, a person could still develop one.

Mental Disorders with Genetic Contribution

Major mental disorders, traditionally thought to be distinct, share certain genetic glitches. Autism, attention deficit hyperactivity disorder (ADHD), bipolar disorder, and major depression and schizophrenia have been suggested to possess potential genetic roots and similarities at the biological level. The researchers found that people who had any one of these five disorders carried genetic variations called “CACNA1C”. This gene type  is “known to affect brain circuitry involved in emotion, thinking, attention and memory — functions that can be disrupted in mental illnesses.” According to the study, another genetic variation commonly found among the participants with at least one of the five disorders was CACNB2.

Another of their findings showed that these five disorders were linked to variations in regions of chromosome three and ten. Since a causal relationship has not been pinpointed, they suggested that their findings could only account for (if at all) a small amount of risk for mental illnesses.

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The Important Role of Non-Genetic Factors

While there is growing research about genetics and its direct link to many mental disorders, scientists do know that the environment plays a significant role in the development of mental health conditions. Environmental factors include stress, poor nutrition, substance abuse, death, or other major life losses, neglect, and violence.

Genetic predisposition combined with environmental factors seem to be a more scientifically or socially accepted cause of mental illnesses. A person who is predisposed through genetics or family history is more likely to develop symptoms of mental illnesses when they experience one or more of these environmental factors.

Childhood experiences – physical, mental, and sexual abuse, have been shown to be somewhat correlated with mental illnesses as adults. A study by the CDC showed the effect of adverse childhood experiences and its result on well being as an adult, especially when it comes to mental health. Their results showed that two-thirds of the participants who had experienced one or more traumatic events in their childhood currently experience negative health and well being outcomes.

Chronic Stress and Biological Factors

The stress-diathesis model attempts to explain the biological relationship between someone’s predisposition for a mental health condition and major or ongoing stressors. A combination of stressors like work, life, marriage, finances, and academics, coupled with genetic predisposition, may also play a role in mental health issues. Your chances of having a mental illness increases when genetic predisposition is met with major or ongoing stressors in your life. Poverty, for example, can be a major or ongoing stressor. It has also been shown to play a role as an environmental factor that can cause mental illnesses, since poverty can be a vicious cycle.

Living in poverty for any significant length of time is a major stressor that increases all sorts of risk factors for health and mental health problems. One becomes more stressed, worries about money constantly, and is concerned with how he or she is going to pay the bills. Similarly, one does not eat as well because unhealthy and processed food is often cheaper than nutritional food. If one can still afford to live on his or her own, he or she will likely do so in a neighborhood more prone to violence, exposing one (and one’s children) to more trauma and risk for personal violence, which can lead to different mental illnesses.

While there is insufficient research to link genes directly to mental disorders, certain gene variations, family history, and environmental factors working together have been shown to have a causal relationship with mental illnesses. It is important to know that mental illnesses are complex, and some can develop even in the absence of all these factors. If you or someone you know is experiencing symptoms of a mental illness, you should consult a mental health professional to help guide you on treatment options.

Adebolanle A.I. is a Mental Health Social Worker and Registered Behavioral Technician. She has many years of experience writing and advocating for mental health awareness. She runs a mental health and lifestyle website, where she shares tools to help individuals work through daily life challenges.