Genetics of anxiety
Recent advances in our understanding of the way mental illness operates are promising to pave the way for changes in the way we deal with these conditions in the future.
An excellent example of this sort of advance in understanding applies to the way the genetic basis of anxiety disorders is beginning to be understood today.
Although it is generally accepted that most psychiatric disorders have a strong genetic component to them, it hasnít been of much practical use yet since we have not been able to identify exactly which genes are involved or how they contribute to the expression of the illness.
Anxiety disorders such as generalized anxiety, panic disorder, obsessive-compulsive disorder, post traumatic stress disorder and social anxiety disorder are common in the case work of most psychiatrists. Indeed, these are some of the most commonly occurring psychiatric illnesses and affect up to one in five Canadians. Recent advances in the understanding of these conditions could lead to better treatment and outcomes for the many people affected by them.
Recent animal studies have found that it is possible to breed for greater or lesser degrees of behaviour that seems similar to human anxiety Ė even though the animals obviously canít tell us they are feeling anxious.
Beginning with mice bred to be anxious, researchers have screened the expression of their genes to learn which ones differentiate them from non-anxious mice. This research has led to the identification of a small number of potential genes involved in the anxiety response.
From a possible 10,000 genes, the list has now been narrowed down to about five potential genes.
Next, these genes were attached to a virus which was injected into brain regions known to be involved in anxiety. Researchers found that this caused overexpression of the genes and increased the level of anxiety in the mice.
Gene silencing using injected RNA to inhibit the anxiety causing genes then worked to change the behaviour as predicted. Mice showed less anxiety.
Although these are very exciting findings with obvious potential human application, that remains years away as further refinements in our knowledge are needed through animal research. Still, it is a large step forward in our understanding of the way anxiety disorders work on a genetic level.
In other research, it appears that a gene on chromosome nine is somehow related to obsessive compulsive disorder (OCD). It seems to trigger symptoms by sabotaging the normal functioning of the neurotransmitter glutamate in the brain.
Various imaging, animal and neurochemical studies have implicated abnormal glutamate activity in OCD and the current research shows that a particular gene is crucial in terminating the action of glutamate in the brain Ė thus contributing to symptoms of this disorder.
These findings will need to be replicated before we have certainty about their accuracy. It will also need to be determined which variations of the specific genetic sequence are the ones that cause the problem.
Once the variants have been identified, more research will determine how to manipulate them in ways that might benefit patients with OCD. All of this will likely take a number of years.
Although there is still much to do before we fully understand the mechanisms underlying symptoms of anxiety, it is exciting to see the advances that are currently underway. It may well be that within a decade we will have the knowledge necessary to design more effective treatments based on our new understanding of these conditions.