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It’s often claimed that mental illnesses derivate from a ‘’chemical imbalance’’ on the brain –that occurs when there’s either too much or too little of certain chemicals, called neurotransmitters- but that would be diminishing how complex those disorders are. In fact, APA (American Psychiatric Association) defended in 2005 that ‘’the exact causes of mental disorders are unknown’’. In that same year, Drs Thomas Insel and Remi Quirion proposed that mental disorders need to be ‘’addressed as disorders of distributed brain systems with symptoms forged by developmental and social experiences.”

Pies, RW. (2014, April) Nuances, Narratives, and the ‘’Chemical Imbalance’’ Debate [Blog Post.] Retrieved from https://www.psychiatrictimes.com/view/nuances-narratives-and-chemical-imbalance-debate (last accessed on 13th October 2020)

Mental illnesses don’t simply result from an amount of certain brain chemicals, but of a set of probable causes, such ‘’as faulty mood regulation by the brain; genetic vulnerability; stressful life events such as a history of physical, psychological, or emotional abuse; medications; medical problems genetics; family history; having a history of alcohol or illicit drug use and taking certain medications psychosocial factors, such as external circumstances that lead to feelings of isolation and loneliness’’.

Harvard University. (2009, June) What causes depression? Harvard Health Publishing Retrieved from https://www.health.harvard.edu/mind-and-mood/what-causes-depression; Eske, J. (2019, September) Everything you need to know about chemical imbalances in the brain, Medical News Today Retrieved from https://www.medicalnewstoday.com/articles/326475#myths (last accessed on 13th October 2020)

However, chemicals are involved, it’s just not as simple as ‘’one chemical being too low and another too high”, but of millions and billions of chemical reactions working both inside and outside of nerve cells. There are specific areas of the brain that regulate it so scientists believe that the cause of these disorders might lie in the nerve cell connections, nerve cell growth and functioning of nerve circuits rather than on levels of brain chemicals. The use of antidepressants supports this theory because despite the immediate increase of chemical messengers on the brain, the patients take several weeks or longer to feel results. The researchers started to question why; if depression was only the result of low levels of neurotransmitters, how come people didn’t feel better as soon as their number is increased? They then progressed their theory to ‘’the real value of these medications may be in generating new neurons (a process called neurogenesis), strengthening nerve cell connections, and improving the exchange of information between nerve circuits. If that's the case, depression medications could be developed that specifically promote neurogenesis, with the hope that patients would see quicker results than with current treatments.’’ However, the understanding of the neurological function influence in disorders is incomplete and therefore, susceptible to change.

Burns, D.D. (2017, December). Do depression and anxiety result from a Chemical Imbalance in the brain? [Blog Post]. Retrieved from https://feelinggood.com/2017/12/12/do-depression-and-anxiety-result-from-a-chemical-imbalance-in-the-brain/ (last accessed on 13th October 2020)

Professor David D. Burns, a winner of A. E. Bennett Award from the Society for Biological Psychiatry, among others, dedicated a long time of his life studying the chemical imbalance theory but stopped when he ‘’realized that the chemical imbalance theory was not a productive or valid.’’ In one of his clinical studies, he flooded the brains of depressed veterans with serotonin – a neurotransmitter that was believed to cause depression when in deficiency- but there was no effect on their moods or disease. This led him to believe that the theory wasn’t accurate and he now defends that although there are biological brain disorders, he finds unlikely that mental disorders are a ‘’chemical imbalance’’ since the brain itself it’s not a ‘hydraulic system of balances and imbalances.’’. Instead, he thinks that ‘’Everything about being human results from biological (genetic) and environmental influences—such as IQ, personality, height, hair colour, and the proclivity to being naturally more negative in outlook (depression, anxiety, shyness, anger) or more naturally positive (happy, confident, outgoing). However, we do not yet have much understanding of the brain systems that are involved. To what extent is depression the result of problems with our hardware (tissue level brain abnormalities or damage) vs. software (learning, neural circuitry, etc.)? We just don’t know.’’

Depression

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