ANTIDEPRESSANTS Lachlan Carmody Medication and Evolution Rationale The claim, “Modern day medicine is to blame for the halt in human evolution” has several aspects that can be investigated. The first aspect considered is that humans adapt and change over time, that humans evolve. Darwin (1859) stated, “evolution is the process by which organisms change over time as a result of changes in heritable physical or behavioural traits.” (Than, 2018). The second aspect of the claim is that modern medication has had an impact on human evolution. Initial research indicated that natural selection, “defined as a process by which species of animals and plants that are best adapted to their environment survive and reproduce, while those that are less well adapted die out” (Australian Museum, 2018) is a mechanism of the evolution process. Evolution is the process by which a species with characteristics that have assisted them to adapt to their environment, will tend to leave more offspring and those less adaptable will die out or leave fewer offspring, so in time over the course of generations there is an increased tendency for greater adaptation of the species (Than, 2018). Advances in modern medication has seen lives prolonged beyond those seen in previous generations. Generally modern medication is perceived as having a positive impact on human health and well-being. Research revealed anti-depressant medication has been developed to assist in stabilising chemical imbalances in the brain. Further research revealed mental health issues such as depression and anxiety have a genetic link, that may on further investigation be associated with unfavourable traits such as chemical imbalances in the brain being passed on to the next generation by those that would previously have died. Subsequently, the research question to be investigated is as follows: Does antidepressant medication affect how our body naturally adapts to stress? If it can be established using evidence, that antidepressant medication has a positive impact on suicide rates (reduced suicide rate), then the second aspect of the claim, that modern medication has impacted on human evolution can be supported. Overview of the use of anti-depressant medication Anti-depressants are a form of medication which aim to correct chemical imbalances of neurotransmitters in the brain, which are known to change mood and behaviour. Antidepressants can help relieve symptoms of depression, anxiety disorders, as well as other mental health conditions. The most commonly prescribed anti-depressant is SSRI (selective serotonin reuptake inhibitors). The process of SSRI’s is to block the chemical serotonin from reabsorbing into the body, increasing levels of serotonin in the brain. Serotonin is the “feel good” chemical and allows communication between neurons in the brain. Prozac, Lexapro, Celexa, Paxil and Zoloft are among the labelled Selective Serotonin Reuptake Inhibitors (SSRI's). Generally, it is assumed that antidepressants are beneficial for symptoms of depression, including suicidality. There is evidence to suggest that Selective Serotonin Reuptake Inhibitors (SSRIs) may cause worsening of suicidal ideas in vulnerable patients. This seems more evident in children and adolescents and is less clear for adults (Nischal, A, Tripathi, A, Nischal, A, and Trivedi, J.K, 2012). Although absolute evidence is lacking at present, recent reports from some European countries strongly suggest that increasing utilisation of antidepressants is one of the most important contributing factors in the decrease in suicide rates (Rihmer, 2001). There is however, other treatments and environmental factors that support recovery from depression and anxiety, including psychotherapy and other support networks. The development of anti-depressant medication has changed how individuals are treated for moderate to severe mental illness, however there is conflicting evidence to support the impact it has on suicide rates across various a cross section of the population. "Medicine has made it possible to deal with many conditions. Our lives are longer” (Childs & Kansangra, 2007). Genetic link in depression and mental health disorders Lewine (2013) reported on the Psychiatric Genomics Consortium analysis of DNA from 33000 people with major depression, bipolar, schizophrenia, autism or attention-deficit hyperactivity disorder and 28000 without these disorders. In the group with the disorders, four regions of the genetic code carried the same variations. It is evident that mental health disorders have a genetic link. A person with a family member with depression is almost five times more likely to develop symptoms (Faris, 2017). The chromosome 3p25-26 was linked to families with recurrent depression. It is believed that as many as 40 percent of those with depression can trace it to a genetic link and 60 percent linked with environmental and other factors (Faris, 2017). Heredity and environmental factors have a strong influence on whether an individual is more likely to have depression if their parents or siblings have it. A person growing up with someone with the disease is likely to mimic behaviours in certain settings or normalise behaviours that are not otherwise seen as normal in an individual without depression, for example spending numerous days in bed. It is evident that genetics have a strong link in determining whether an individual is likely to develop mental illness such as depression or anxiety. Evidence – Suicide rates and use of anti-depressants Suicide remains the leading cause of death for Australians aged between 15 and 44 (Lifeline, 2020). On average, one person dies by suicide every 40 seconds somewhere in the world with 1.8% of worldwide deaths declared a suicide. (suicide.org, 2020). Statistics vary across the globe, with more developed countries on average having higher suicide rates, despite assumed access to anti-depressant medication and treatment (suicide.org, 2020). Erlangsen, Canudas-Romo, and Conwell (2008) analysis of rates of suicide and antidepressant medication consumption initially reveals that as anti-depressant sales increase over time, suicide rates decrease. Suicide rate per 100 000 and sales of antidepressants (measured as defined daily dose per 1000 inhabitants per day) in Denmark during 1996– 2000 was illustrated, see Figure 1, Appendix 1. The change in suicide rate does not decrease at the same rate with the increase in anti-depressant sales. Approximately 14% of men and 30% of women who died by suicide were in treatment with antidepressants at the time of death. The overall suicide rate for men aged 50 years and over decreased from 41.8 in 1996 to 32.1 per 100 000 in 2000. The female rate declined by 3.7 suicides per 100 000 from 16.7 to 13.0 per 100 000 over the same period (Erlangsen etal. 2008). It can be suggested that those that would otherwise have perished due to suicide (without antidepressant treatment) have lived longer to enable them to have offspring, passing on the less desirable traits to the next generation The research question, “Does antidepressant medication affect how our body naturally adapts to stress?” was addressed by gathering evidence. The evidence suggests that there is a decrease in suicide rates with increases in anti-depressant medication rate of purchase. However, it was found that only a small number of those that committed suicide, one in five, was taking anti-depressant medication at the time. The majority of decrease in suicide rates was found in the group that was not actively taking anti-depressant medication. Several studies in US and Nordic countries have shown that new less toxic medications are associated with only a moderate decrease in the overall suicide rates, varying in sex and age groups (Faris, 2017). It is therefore unlikely that a firm conclusion can be made that antidepressant medications are impacting on suicide rates at a rate that is able to substantiate that there is an impact on evolution and how our bodies naturally adapt to stress. The findings of this investigation are not able to fully support the claim that modern day medication is to blame for the halt in human evolution. Evidence Evaluation Research studies suffer from an inability to relate antidepressant medication to suicidal behaviour, at the level of the individual (Zampieri, 2017). It is evident that there are other factors that impact on suicide rates and rates are not equitable across countries. Future research may benefit from examining the influence of societal factors on changes in the suicide rate using data at an individual level. Studies that look at recovery, age and sociodemographics over a period of time may shed more light on the actual impact of antidepressant medication and the likelihood that undesirable genetic traits are passed on to future generations, thus impacting on evolution. The research from Erlangsen etal. (2008), took into account suicide rates and purchase of anti-depressants, it was however unable to provide data that was able to identify the individuals’ diagnosis and the impact this had. The data was not based on the lifespan of an individual, and therefore unable to provide evidence of the impact through subsequent generations. While a large sample size was used, the study is not able to confirm if medications were actually consumed and if those that were not actively taking medication were deemed as recovered from their illness. Nor did it take into account outside environmental factors that may impact on suicide rates or those that may have undiagnosed co-morbid conditions. Further research should consider how medication changes human behaviour and our environment. Given that medicine is considered to be related to human evolution, medical sciences should be well informed about the evolutionary theory and evolutionary processes. Evolutionary biology can be crucial in disease control, and therefore it may have an important role to play in the design of medical intervention (Fabio, 2017). Conclusion Upon review, there has not been sufficient evidence gathered to establish whether antidepressant medication affects how our body naturally adapts to stress and the impact over time on human evolution. There is however not enough evidence to refute this claim. Therefore, the claim “Modern day medicine is to blame for the halt in human evolution” is not able to be supported by this research, but at the same time is not discredited by the findings of this research. Further investigation is required to understand the multiple factors that impact on human longevity and the impact mental health and other chronic diseases have across multiple generations, when treated and untreated. References Australian Museum. (2018). https://australianmuseum.net.au/learn/species-identification/askan-expert/what-is-natural-selection/ What is natural selection. Ayala, F. (2020). https://www.britannica.com/science/evolution-scientific-theory Evolution: Scientific Theory Childs, D. & Kansangra, S. M.D. (2007). ABC News Medical Unit. https://abcnews.go.com/Health/TenWays/story?id=3605442&page=1 10 Health Advances That Changed the World. Erlangsen, A, Canudas-Romo, V, and Conwell, Y. (2008). Increased use of antidepressants and decreasing suicide rates: a population-based study using Danish register data. Journal of Epidemiology and Community Health, 62(5): 448-454. Fabio, Z. (2017). On Human Nature. Chapter: The Impact of Modern Medicine on Human Evolution. pp.707-727. Faris, S. (2017). Is depression genetic? Extracted from: https://www.healthline.com/health/depression/genetic John, P. (2016) https://www.britannica.com/science/natural-selection Natural selection Lewine, H. (2013). https://www.health.harvard.edu/blog/shared-genes-link-depressionschizophrenia-and-three-other-mental-illnesses-201303015944 Lifeline. Extracted 01/06/2020 from https://www.lifeline.org.au/about-lifeline/lifelineinformation/statistics-on-suicide-in-australia Nischal, A., Tripathi, A., Nischal, A, and Trivedi, J.K. Sana, M. (2012). Suicide and Antidepressants: What Current Evidence Indicates. Mens Sana Monogr, 10(1): 33–44. Rihmer, Z. (2001). Can better recognition and treatment of depression reduce suicide rates? European Psychiatry, 16(7): 406-409. Than, Ker. (2018). https://www.livescience.com/474-controversy-evolution-works.html What is Darwin's Theory of Evolution? Zampieri, F. (2017). https://www.sciencedirect.com/science/article/pii/B9780124201903000430 The Impact of Modern Medicine on Human Evolution. Webpage extracted 01/06/2020 http://www.suicide.org/international-suicide-statistics.html Appendix 1 Figure 1. Suicide rate per 100 000 and sales of antidepressants measured as defined daily dose per 1000 inhabitants per day in Denmark during 1996–2000. 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