Are Mental Health Disorders Genetic?
About one in five adults will experience a mental health disorder at some point in their lives. Many of these disorders begin earlier in life than others, and some can be triggered by stress or other events.
Most people with a mental health disorder do not have any inherited genetic traits. But if you have a family history of a mental illness, you may be more likely to develop it.
Inherited traits
People are often told that mental health disorders “run in families.” This means that a person is more likely to develop a mental disorder if his or her blood relatives have the same condition. However, this is not always the case.
The reason for this is that many psychiatric illnesses have a complex genetic and environmental origin, with no single gene switch that flipped to cause a mental illness. It is also important to remember that experiences and life situations can trigger mental disorders.
Studies have shown that some of the major mental illnesses – autism, ADHD, bipolar disorder, depression and schizophrenia – share common inherited risk factors. These findings provide a useful starting point for understanding how genetics affect these conditions and help researchers find more effective treatments.
Environmental factors
While mental health disorders sometimes run in families, they are not necessarily inherited. Instead, they can be caused by a combination of genetic changes and environmental factors. This is called multifactorial inheritance.
The relationship between environmental and genetic factors in mental health disorders is complicated. Some research shows that certain environments can increase the risk of mental illnesses, but others don’t.
For example, air pollution can lead to increased rates of depression and other mental health conditions. Other environmental factors that can affect mental health include poor nutrition, drug abuse, and exposure to toxic chemicals.
Studies show that having a first-degree relative with schizophrenia increases the risk of developing the disorder later in life. However, environmental factors play a larger role in psychiatric illness than does genetics.
Brain chemistry
Every thought, emotion and action we experience is created through chemical processes in the brain. These chemicals are called neurotransmitters. Examples include serotonin and dopamine.
Some researchers think that mental health disorders are caused by a chemical imbalance in the brain. However, this theory runs the risk of oversimplifying these complex diseases.
The way these neurotransmitters are produced and released by the billions of neurons in our brains depends on many factors, including genetics and the environment.
These factors are unique for every individual, and mental illness often runs in families. That’s why people who have a family member with a mental illness are more likely to develop one themselves.
New research suggests that certain genes may be associated with neuropsychiatric disease risk at different times of brain development — including during fetal and adolescent growth. This could explain why certain psychiatric conditions have similar symptoms and how we might better understand their causes.
Neurotransmission
Mental health disorders may be caused by a variety of factors, including inherited traits, environmental influences, and chemical imbalances in the brain. Neurotransmitters are chemicals that pass information between neurons in the brain.
The nervous system contains more than 40 neurotransmitters, including acetylcholine (ACh), dopamine, norepinephrine, and serotonin. These neurotransmitters are released into the synaptic cleft to interact with receptors on other nerve cells.
Once in the cleft, the neurotransmitters bind to the receptor proteins on the cell membrane of the target tissue. The result can be excitatory or inhibitory.
The process of neurotransmission involves repeated cycles of exocytosis and endocytosis at specialized areas called synapses. The synapse is a highly specialized contact between presynaptic and postsynaptic neurons built to transmit information with high fidelity.
