In the Genes: Is Depression Genetic?

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Depression is a topic that gets everyone talking today, which is fantastic progress considering that it was a taboo topic of conversation a couple of decades ago. Although society knows more about depression, bipolar disorder and other forms of mental illness than ever before, there are still several questions asked as to where it comes from and why some people are affected and others are not. One of the most asked questions is undoubtedly whether depression is genetic.

The causes of depression that are non-genetic are well known and documented. There is no one overriding cause but triggers that vary from individual to individual. For example, the NHS website lists bereavement, divorce, redundancy, financial difficulties, stress, illness, isolation and the use of alcohol and/or drugs as triggers. Depression can manifest during childhood or occur for the very first time in a senior citizen. There is no blueprint as to why people suffer with depression and other similar mental illnesses and disorders but there is little doubt that, if your parents or siblings have depression, you are more likely to suffer with it yourself. 20% to 30% more likely in fact.

Prior to the start of 2011, medical experts and scientists alike tended to agree that depression does have a genetic base in some cases. That is not to say that individuals who have no family history of depression cannot get it. The truth is that anybody may become susceptible to depression at any time. However, according to Stanford University’s Dr Douglas Levinson and Dr Walter Nichols, there are genetic factors. For example, two times more women than men suffer from major depression and there are patterns of familial depression, with parents and siblings displaying the same disorders and issues.

David Moore and James Jefferson draw attention to another study in the Handbook of Medical Psychiatry that seems to point to there being a genetic link for the onset of depression. Several studies of twins have found that non-identical twins have a 20% major depression rate but identical twins have a 50% major depression rate. The former share less genetic material than the latter. As such, it stands to reason that there is a genetic connection.

However, Dr Levinson and Dr Nichols also point out that: “… no one simply “inherits” depression from their mother or father. Each person inherits a unique combination of genes… and certain combinations can predispose to a particular illness.” At least, this was the belief until recently.

In May 2011, a study offered significant proof that depression is indeed genetic. A group of researchers from Kings College London actually found that a region of DNA that contains up to 40 genes has at least one that is more than likely to cause depression. Chromosome 3p25-26, as the region is otherwise known, has been pinpointed after a study of 839 British families revealed that there are identifiable variations within DNA that contribute to the prevalence of depression. Although the conclusions reached do need further research and are not comprehensive at the current time, they certainly offer an insight into the question as to whether depression is genetic.

This study has made a major breakthrough in answering the question as to whether depression is genetic or not. Although it has confirmed what many experts believed to a degree, there is still a long way to go before chromosome 3p25-26 is confirmed as the source of genetic issues related to the illness. It should give hope to those who have a family history of mental illness linked to depression but there is still much to do before effective treatment for genetic depression can be found.

In short, yes, depression is genetic to a certain degree but it may also be caused by environmental issues. Whether you have it in your family or not, it is definitely worth taking care of your mental health as far as possible in an attempt to keep it at bay.

Sources:
1) Stanford School of Medicine
2) NHS Choices
3) David P. Moore and James W. Jefferson. Handbook of Medical Psychiatry. 2nd Ed. Philadelphia: Mosby, Inc., 2004.