Mention that you are researching ‘genetics and mental health’ and you might notice a sense of unease in your audience. We usually tack on additional information, which ranges from, “investigating how we can predict response to psychological therapies using genetic information, and of course we incorporate environmental factors too”, to “but don’t worry, not in a eugenics-y way”, depending on the context. Here, Meg [EditLab PhD student] discusses why we shouldn’t be afraid to talk about the genetics of mental health.
It’s unsurprising that there is still an element of fear about genetics in research, given the history of how mankind has abused it. The Nazi campaign for a ‘superior’ race was undertaken by forced sterilisation and murder of those deemed undesirable, including psychiatric patients (Torrey & Yolken, 2009). With the mapping of the human genome in 2003 and developments in assistive reproductive technologies there have been renewed fears of eugenics. Arguments against eugenics aside (reduction of healthy genetic variation in the population, loss of potentially beneficial genes, ambiguity over who determines a ‘desirable’ trait, and how, to name a few), I think much of the fear stems from a misunderstanding about how genes work.
“Most behavioural traits are ‘polygenic’; the result of many genetic factors interacting with each other and with the environment”
Like the majority of people, my introduction to genetics was in school lessons on Mendelian genetics, where we learnt that the inherited gene for a trait determines the observable outcome. In fact, single-gene traits and disorders are very rare and don’t account for the wide range of behaviours we observe. Most behavioural traits are ‘polygenic’; the result of many genetic factors interacting with each other and with the environment. That trait will lie on a normally distributed continuum, with fewer people at the extremes, such that someone with depression may be at the extremes of several traits that constitute a diagnosis of depression. This means that they are not categorically different to the non-depressive population, but their position on this continuum may seriously impact on their wellbeing. As Robert Plomin puts it, “Abnormal is normal” (Plomin et al., 2016) – I personally think that this is a really important message with implications for reducing stigma in mental health.
“Identifying the genetic factors associated with mental illness is vital to make decisions about who is likely to develop an illness, so that interventions can be put in place”
If you know that depression runs in your family, that does not guarantee that you will get it too. There are genetic factors that confer ‘risk’ for a mental illness (or for more than one – see Eley, 1997), but environmental factors, and how these interact with genetics, are important . If you don’t have any genes related to a disorder, perhaps regardless of your specific environment, you are resilient to mental illness. Alternatively, if you do have a genetic predisposition, perhaps a protective environment means you never develop the illness. Or, maybe through your genetic predisposition you developed an illness, but changing the environment, for example through psychological therapy, alleviates it.
Genetic research in the context of mental health is necessary…not scary! Identifying the genetic factors associated with mental illness is vital to make decisions about who is likely to develop an illness, so that interventions can be put in place; for uncovering how genes interact with the environment in a protective manner, including exploring responses to therapy (see therapygenetics); for exposing biological pathways that might be successfully targeted with drug therapies. It’s not about editing the inherited genetic structure, but in finding ways to prevent and treat mental illness using our understanding of both genetics and the environment – nature and nurture.
Eley, T. C. (1997). General genes: A new theme in developmental psychopathology. Current Directions in Psychological Science, 6(4), 90-95.
Plomin, R., DeFries, J. C., Knopik, V. S., & Neiderhiser, J. M. (2016). Top 10 replicated findings from behavioral genetics. Perspectives on Psychological Science, 11(1), 3-23.
Torrey, E. F., & Yolken, R. H. (2009). Psychiatric genocide: Nazi attempts to eradicate schizophrenia. Schizophrenia bulletin, 36(1), 26-32.