NEW RESEARCH TECHNIQUES OFFER HOPE IN TREATING EXPLOSIVE BEHAVIORS

New techniques in genetics are starting to shed light on a number of psychiatric disorders. In a harmless procedure, a swab is rubbed in the child’s mouth to obtain a few inner cheek cells for genetic analysis. Sometimes referred to as "Gene Mapping", this form of analysis has provided new insights into impulsive and aggressive juveniles. For example, LaHoste and his colleagues have recently found evidence for a genetic variant in about 50% of children diagnosed with Attention Deficit Hyperactivity Disorder. The gene was the D4 gene, one of several genes important for a brain chemical called dopamine.

A research group has conducted a study that showed about half of impulsively aggressive juveniles have a genetic variant in their D2 gene, another dopamine gene. Dopamine can have a stimulating effect in the brain, but it also can stimulate "inhibitory" brain sites. When "inhibitory" brain sites are stimulated, then dopamine acts like a behavioral "brake" by stopping behavior temporarily. In this way, behavior becomes less impulsive, since the individual is able to stop and consider consequences before acting. If this brain’s "brake" is not working, due to a genetic variant of the dopamine gene, then the individual may become pathologically impulsive. This may result in an increase in impulsive aggression, as well as other impulsive behavior. This could explain why consequences (punishments) do not seem to influence these individuals, since, without a "brake", they cannot stop their behavior to consider past consequences.

The same research group has also conducted a pilot genetic study of 11 children with a condition known as INTERMITTENT EXPLOSIVE DISORDER. This rare condition is characterized by severe episodes of unprovoked rage behavior, occurring on an intermittent basis with relative calm in-between these "spells". In some cultures the term "Running Amok" is used to describe a single episode of this type of abrupt violence (followed by lack of memory for the event). For Intermittent Explosive Disorder, the episodes of violence happen repeatedly, preceded only by a sense of tension. After the "attack" the individual may be remorseful. This new gene mapping technique was tested on a small sample of 11 juveniles who had been hospitalized with a diagnosis of Intermittent Explosive Disorder.

In this pilot study, all 11 juveniles (100%) showed an aberrant pattern in the DAT1 gene, another type of dopamine gene known as the "transporter" gene for dopamine. This suggests that this condition of episodic unprovoked rages may be genetic in origin, and that this form of gene mapping might be used as a genetic marker for the disorder.

These small studies need to replicated. Only then will scientific evidence support the theory that rage behavior, of this type, has a genetic basis and is related to the neurotransmitter, dopamine, in the brain. Then treatment options that prevent, stabilize or reverse this dopamine problem can be explained. These efforts will hopefully result in better diagnostic techniques and better treatment outcome.

The senior author of these studies was Dr. K. Blum, a geneticist with UTHSC School of Public Health at Houston Department of Behavioral Sciences, 7703 Floyd Curl Drive, San Antonio, Texas 78284-7926. Dr. Dan Matthews, our Medical Director, and Dr. L. Fisher, Director of Neuropsychology, were among the co-authors. Another study from our research group is:

Blum, K., et.al., (1997). Association of polymorphisms of dopamine D2 receptor (DRD2) and dopamine transporter (DAT1) genes with schizoid/avoidant behaviors (SAB), Molecular Psychiatry, 1, 1-7.

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