[Paleopsych] BBC: Brain structure link to anxiety

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Brain structure link to anxiety 
http://news.bbc.co.uk/go/pr/fr/-/2/hi/health/4671483.stm Published: 
2005/10/31 00:17:25 GMT [Thanks to Laird for this.]

Vulnerability to anxiety may be down to the size of a brain structure 
involved in fearful memories, say US scientists.

People with a thicker ventromedial prefrontal cortex were better able 
to cope with stressful experiences.

The findings may help explain why some people develop post-traumatic 
stress disorder (PTSD) while others bounce back after adversity, say 
the authors.

The Massachusetts General Hospital study appears in Proceedings of the 
National Academy of Science.

Fear factor

While it is normal to experience physical and psychological symptoms 
after an extremely stressful event, such as the recent London 
terrorist attacks, some people will continue to be consumed by 
overwhelming fear and may develop PTSD.

"Certainly, that part of the brain is associated with a whole manner 
of psychiatric vulnerabilities," Dr Cosmo Hallstrom, consultant 
psychiatrist in London

A person with PTSD may experience unwanted flashbacks, poor sleep and 
depression, and avoidance certain situations that could trigger 
memories of the event.

Studies in animals suggest that the ventromedial prefrontal cortex 
(vmPFC) is involved with helping the brain forget fearful events.

Also, studies of have shown that people with PTSD have unusually 
inactive vmPFCs, again suggesting that this brain region is important 
in anxiety.

In the current study, Dr Mohammed Milad and colleagues scanned the 
brains of 14 volunteers.

Sweaty palms

The volunteers were also exposed to a series of experiments, involving 
harmless but uncomfortable electric shocks, which were designed to 
cause anxiety.

The volunteers who had the least anxiety responses, gauged by how 
sweaty their palms were during the tests, tended to have thicker 
vmPFCs and vice versa.

Dr Milad said: "These results suggest that a bigger vmPFC may be 
protective against anxiety disorders or that a smaller one may be a 
predisposing factor."

However, he said they did not yet know who that might work.

His colleague Dr Scott Rauch said the next step was to look at genetic 
and factors in the environment that might explain the brain 
differences.

In the future, it might be possible to measure a person's vmPFC to 
predict whether they are more prone to anxiety disorders such as PTSD.

Dr Cosmo Hallstrom, consultant psychiatrist in London, said: "We know 
that some people are more vulnerable to stress and anxiety and it is 
nice to have a biological correlate of that.

"Certainly, that part of the brain is associated with a whole manner 
of psychiatric vulnerabilities.

"It is not surprising that anxiety disorders may also have part of 
their underlying vulnerability in that area."

He said important thing was to recognise was that PTSD is treatable 
and should be managed as early as possible.