Post-traumatic stress disorder linked to genes
By William Smith
Different people who experience the same ordeal have different responses to it. Whilst some people seem to go through traumatic experiences 
unscathed, others can be floored by it. A new UCLA study looks at why some people fall foul of post-traumatic stress disorder (PTSD) whilst others, with experience of the same ordeal, do not.
A link between two genes involved in the production of serotonin and a higher risk of PTSD has been found by the UCLA researchers. Their findings suggest that vulnerability to PTSD is inherited and as a result this could lead to new ways of screening and treatment of the disorder.
The study findings can be found online in the Journal of Affective Disorders. The study lead author is Dr. Armen Goenijan who is a research professor of psychiatry at the Semel Institute for Neuroscience and Human Behaviour at UCLA.
Goenijan says ‘People can develop post-traumatic stress disorder after surviving a life-threating ordeal like war, rape or a natural disaster. If confirmed, our findings could eventually lead to new ways to screen people at risk for PTSD and target specific medicines for preventing and treating the disorder.’
PTSD is usually associated with exposure to war or extreme combat, however it can also affect individuals who have been exposed to child abuse, sexual or physical assault, terrorist attacks, natural disasters and major accidents. More recent study has shown that it can also affect emergency call handlers who are on the front line of calls for emergency help.
The symptoms of PTSD are many and varied but can include flashbacks, being on constant alert to danger and feeling emotionally numb. All too often these symptoms lead to the avoidance of situations which could remind the sufferer of the original trauma.
For this study, Goenijan and his fellow researchers took DNA samples from 200 adults spanning several generations of twelve families. The participants suffered from PTSD after experiencing the disastrous 1988 Armenia earthquake.
It was found, when examining the genes in the families, that people with specific variants of two particular genes were at a greater risk of developing the symptoms of PTSD. These genes are known as TPH1 and TPH2 and are responsible for serotonin production. Serotonin is a chemical in the brain which controls sleep, alertness and mood.
Goenijan says ‘We suspect that the gene variants produce less serotonin, predisposing these family members to PTSD after exposure to violence or disaster. Our next step will be to try and replicate the findings in a larger, more heterogeneous population.’
PTSD is a subject that is currently topical with many of us reminded at this time of the 30th anniversary of the Falklands conflict. With a large number of our servicemen currently engaged in Afghanistan and recently returning from Iraq, and with many ex-servicemen still suffering from the consequences of other combat situation around the world, PTSD is a pressing health issue.
‘A diagnostic tool based upon TPH1 and TPH2 could enable military leaders to identify soldiers who are at higher risk of developing PTSD, and reassign their combat duties accordingly. Our findings may also help scientists uncover alternative treatments for the disorder, such as gene therapy or new drugs that regulate the chemicals responsible for PTSD symptoms,’ said Goenijan.
When it comes to prescribing medication to treat the symptoms of PTSD psychiatrists currently rely on a 'try it and see' approach, however, this research could lead to PTSD being identified by using brain biology rather than simply from clinical observation, Goenijan suggests.
