Stress response

Have you ever wondered why people react so differently to traumatic events?

Thousands of people could be involved in the same traumatic situation - such as a natural disaster or war – yet some will experience long term effects like post traumatic stress disorder (PTSD) and others will not.

Research supports the theory that a combination of factors including genetics and environmental influences throughout life can work to change the biology of the stress response system as it develops.

One study found a person is much more likely to develop PTSD after a traumatic event if physical or sexual abuse were experienced during childhood and if certain gene variations exist.

Nine hundred people aged 18 to 81 from low income urban American neighbourhoods were surveyed and genetic information was also collected. Many volunteers had experienced severe traumatic experiences in childhood and later as adults.

Almost 30 per cent of study participants had a history of child abuse and this led to more than twice the number of PTSD symptoms among adults who later experienced traumatic events.

But abuse in childhood wasn’t enough to account for the increased risk of PTSD after adult trauma – it seemed to depend on the existence of certain genetic variations in a particular stress-related gene.

Similarly, the genetic variation alone didn’t seem to increase the risk of developing PTSD after a traumatic event during adulthood. Results from this study point to the need for the combination of both genes and early life experience to dramatically increase the sensitivity of the stress response system.

Variations in multiple genes are estimated to account for between 30 and 40 per cent of the risk of developing PTSD and the gene located in this particular study (called FKBP5) is one of this group – although others still need to be identified.

When examining FKBP5, researchers also found protective variations – people with these variations were not at increased risk of PTSD after trauma even if they had been abused in childhood.

Although more research in this area is needed, it is an important step forward in understanding how nature and nurture interact to affect mental health. As we gain knowledge of this interplay, we will learn more about many illnesses and how to treat and even prevent them. 

In the meantime, it is equally if not more important to find ways to decrease rates of childhood abuse and adult trauma – this may prove key to preventing the development of mental illness in many people.

More States of Mind articles

About the Author

Paul Latimer has over 25 years experience in clinical practice, research, and administration.

After obtaining his medical degree from Queen's University in Kingston, Ontario, he did psychiatric training at Queen's, Oxford and Temple Universities. After his residency he did a doctorate in medical science at McMaster University where he was also a Medical Research Council of Canada Scholar.

Since 1983 he has been practicing psychiatry in Kelowna, BC, where he has held many administrative positions and conducted numerous clinical trials.

He has published many scientific papers and one book on the psychophysiology of the functional bowel disorders.

He is an avid photographer, skier and outdoorsman.

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The views expressed are strictly those of the author and not necessarily those of Castanet. Castanet does not warrant the contents.

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