Genetics may play a smaller role in the depression equation than we've been led to believe. The influence of one particular gene that was long believed to be the most powerful inherited mental health variable has been called into question by recent research. 

There's no question that individuals respond to personal traumas and anxieties differently - almost all go through emotionally difficult periods, but some experience long-term depression severe enough to qualify as a clinical disorder that interferes with all aspects of daily life. The natural question arising from this fact is: what sets these two groups apart? A 2003 study examining the influence of a gene that affects the transportation of mood hormone serotonin named that gene, 5-HTT, as a major player determining the lifetime likelihood of depression. Researchers found that subjects who bore a specific variation of the gene were more likely to respond to various traumas by falling into periods of depression that require medical treatment.

A group of established researchers funded by the National Institute of Mental Health have now released a contradictory report. They did not conduct clinical tests or generate new data for their report. They simply reviewed data gathered from a number of related cases that were designed to mimic and test the results of the original study. Examining 14 separate clinical studies and controlling for all relevant variables, researchers found that subjects who possessed the serotonin transporter variation identified in the original report were no more likely to suffer depression than unaffected control subjects. On the contrary, they found that stressful events like divorce or the death of a close relative raised the probability of depression 40% regardless of a subject's genetic inheritance.

So the 5-HTT gene apparently carries little or no sway in determining respective mental health outcomes. While genetics may leave one more susceptible to the disorders suffered by immediate family members, they do not predetermine one's own fate. Having a parent, aunt/uncle or sibling who suffers from mental illness does not guarantee that a patient will have the same experiences. This is not to say that serotonin and, by implication, the genes that regulate it do not play a large role in determining how certain individuals will respond to personal trauma and recurring anxiety. Neither does the new report completely eliminate the idea of depressive tendencies as inherited traits. It simply states that the specific gene targeted in the earlier study is not the deciding factor in the depression equation. More than anything, it reminds us that chronic clinical depression, anxiety and related conditions are even more complex than we thought - and they demand a greater degree of treatment and scrutiny from all involved. Depression most likely stems from a complex relationship between environment, circumstance and genetics. No single factor holds the key.