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17 April 2014
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OC spectrum disorders

More than a compulsion

As the science behind obsessive-compulsive disorder (OCD) is unravelled, it is becoming clear that many other illnesses may share its underlying cause. Scientists call this family of related illnesses obsessive-compulsive (OC) spectrum disorders.

Man in shadows
Numerous people suffer from an OC spectrum disorder

The relationship of these disorders to OCD is supported by the fact that they all feature intrusive impulses (similar to obsessions in OCD) followed by uncontrollable actions (similar to OCD compulsions).

Loss of control

Everyone has occasionally been tempted to do something out of the ordinary, or inappropriate, or even something that breaks the law. However, most of us are able to resist these impulses.

But people who suffer from OC spectrum disorders find it impossible to resist urges to behave in a way that they know is ultimately harmful, either to themselves or to others.

Major OC spectrum disorders

  • Trichotillomania - a failure to resist the urge to pull out hair, resulting in noticeable hair loss
  • Body dysmorphic disorder (BDD) - sufferers imagine they have a defect in their physical appearance, for example, a pock-marked complexion or a weak chin. They frequently check themselves in the mirror or try to camouflage the body part
  • Kleptomania - a failure to resist impulses to steal objects not needed for personal use or financial gain
  • Compulsive sexual behaviour - uncontrollable sexual thoughts or behaviour that makes the sufferer distressed or causes them to have personal, job or criminal problems
  • Compulsive shopping - excessive and unnecessary shopping that leads to personal, job or financial problems
  • Pathological gambling - A loss of control over gambling habits that results in heavy financial losses and personal or legal problems
  • Intermittent Explosive Disorder - violent outbursts of rage that can result in serious assaults and destruction to property
  • Pyromania - an uncontrollable urge to start fires, associated with a release of tension
Roulette wheel
The lure of the casino can be the road to ruin for pathological gamblers

Common features

A compulsive gambler who has frittered away his savings at the roulette wheel might not seem to have much in common with someone who can't resist an urge to tear out their hair. But both these people are bonded together by a shared experience. Sufferers commonly feel an increased sense of tension or arousal before they commit an act. Then, at the time of committing the act, they experience pleasure or relief.

People with OC Spectrum disorders are often aware of how harmful their behaviour is and, like OCD sufferers, often find their impulses unpleasant and shameful. But just like people with OCD, they are powerless to control their actions.

Controversial theories

Some researchers think that eating disorders such as anorexia nervosa and bulimia are also OC spectrum disorders. But this theory is highly controversial and bitterly disputed.

However, they undeniably share many features. The excessive fear of gaining weight in anorexia nervosa resembles an obsession and the relentless dieting is often described as difficult to resist and distressing, just like an OCD compulsion.

Another candidate for inclusion as an OC spectrum disorder is hypochondriasis. This is a fear of having a serious illness based on a person's misinterpretation of symptoms of disease in their own body.

Biological cause

There is mounting evidence that OC Spectrum disorders, like OCD, are partly caused by a deficiency in the neurotransmitter (brain chemical) serotonin. However, some researchers think an excess of another neurotransmitter called dopamine could be a contributing factor.

Woman pulling a hair out
There is growing evidence that trichotillomania has a genetic basis

All in the genes?

Researchers at the University of Utah have found powerful evidence that trichotillomania, one of the most common OC spectrum disorders, could be inherited. When they created a litter of mice that lacked the gene Hoxb8, the animals began to lick and nibble at their fur until they went bald and their skin became covered in sores.

It's thought that Hoxb8 could be involved in behaviour such as hair-pulling in trichotillomania and hand-washing in OCD.


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