Many of us are touched by mental illness, whether through our own experiences or those of a loved one. This can include common forms of mental illness like depression and anxiety, or less common forms like bipolar disorder and schizophrenia. Often, these experiences lead us to wonder about the causes of mental illness and why it’s happening to us, our child, spouse or friend. Some people may also worry, given their own experiences, that their children or other relatives may be at risk to develop mental illness too.
For decades, scientists have been working to understand why people develop mental illness. The more we learn, the more it becomes clear that the answer is complicated. The inheritance of mental illness can generally be described as “multifactorial”, meaning that there are many genetic factors that interplay with environmental and lifestyle factors to contribute to the development of mental illness. Importantly, genetics is just one piece of this complex puzzle, so while people can inherit a genetic predisposition to mental illness, non-genetic factors (like life stressors) play a role as well.
Psychiatric genetic counselling is a niche area of healthcare in which individuals and families affected by mental illness meet with a certified genetic counsellor who has expertise in this area. A genetic counsellor can work with you to help you better understand what may have led to mental illness in you or your relatives, and what this might mean for other family members. Studies have consistently shown that psychiatric genetic counselling can help decrease the stigma and guilt that some people may feel related to mental illness.1 It can also increase people’s empowerment and self-efficacy related to managing their symptoms, which may lead to better mental health outcomes.2
Many patients with a family history of mental illness also ask whether genetic testing can help them determine the risk of mental illness in themselves or their children. However, because of the complex nature of these disorders, there is currently no useful genetic testing to determine whether you or your child might develop mental illness. Instead, a genetic counsellor may be able to provide an approximate risk assessment based on a detailed analysis of your family history, or “pedigree”, together with data derived from research in this area.
One area where genetic testing can be of use to people experiencing mental illness is in the rapidly evolving field of pharmacogenomics. This is an emerging area of medicine that involves looking at each person’s unique genetic variants and how they impact the way that person processes medications. This type of genetic testing helps doctors better understand and predict how a patient will respond to certain prescription drugs.
Many people who are experiencing mental illness have trouble finding the right psychiatric medication (such as an antidepressant) to control their symptoms with minimal side effects. This can lead to a long and frustrating “trial-and-error” process to find the right treatment. Some studies have shown that it takes an average of four attempts for a Canadian to find an antidepressant that works for them.
While there are many factors that impact how each person responds to a particular medication, and many of these factors are difficult to predict, evidence shows that genetic factors account for anywhere from 20% to 95% of how we break down these drugs.3 With pharmacogenomic testing, we can look at these factors using a blood or saliva sample. From here, doctors can determine which specific psychiatric medications might be most likely to work and least likely to cause adverse reactions in their patient. This can help reduce trial and error so you can find the right treatment sooner and feel better faster.
As with all areas of genetics, our technology, knowledge, and understanding of the link between genetics and mental health continues to advance at a rapid pace. The role genetic counselling and testing play in supporting individuals and families impacted by mental illness will continue to grow and evolve over time.
Heather Andrighetti is a certified genetic counsellor at Medcan who has experience working in psychiatric genetics, in particular with the Vancouver-based Adapt Clinic, which pioneered specialty psychiatric genetic counselling worldwide.