'Help, I Can't Stop Eating'

Even in the absence of drugs, innocuous 
activities can resemble addictions, warns Biplab Das 

Last month, when Hollywood actress Winona Ryder pleaded not guilty to charges of shoplifting and illegal possession of a controlled substance, she may not be have been entirely wrong. Research finds that compulsive behaviour is as much of an addiction as addiction to substances. 

Using refined brain imaging technique, psychiatrists probed the inside of a brain that had been trapped in repetitive, self-defeating behaviour. They came up with stunning insights. Uncontrollable behaviours wreak havoc on a brain in a way that emulates the changes in a brain caused by drugs. 

According to a report published in a recent issue of Science, psychiatrists have pinned down a host of behaviours like gambling, kleptomania (compulsive stealing), pyromania, hair-pulling, eating, sexual and gender identity disorders that culminate in behavioural addictions. 

"Over the past few months, more and more people have been thinking that, contrary to earlier views, there is commonality between substance addictions and other compulsions," says Alan Leshner, head of the National Institute on Drug Abuse (NIDA). 

Of all the self-destructive behaviours under scrutiny, gambling is the commonest one that most resembles drug addiction. Preoccupation with the prospect of immediate financial gain causes cravings as intense as those of a drug addict, in a gambler. "Gamblers even show withdrawal symptoms looking like a mild form of drug withdrawal," says Howard Shaffer, a psychologist who heads the Division on Addictons at Harvard University. 

Withdrawal symptoms include churning guts; sleep disturbance, sweating and irritability. To gain insights into the gamblers' brains, Marc Potenza, a psychiatrist from the University of Yale exposed gamblers to videos of people involved in gambling and talking about gambling. At the same time, theirs brains were subjected to functional magnetic resonance imaging (fMRI). This tracked the activity changes in some of the frontal and limbic brain regions. It resembled the pattern of changes in the brains of cocaine addicts brought about by images that enhance drug craving. 

To test gamblers' drug related response, Suck Won Kim, a psychiatrist at the University of Minnesota Medical School, Minneapolis, tried out naltrexone, an inhibitory drug, on a variety of compulsive behaviours, including gambling. In a trial lasting 11 weeks, 45 gamblers were administered naltrexone. This drug reduced gamblers' urge to gamble as well as the high derived from it. This response to naltrexone proves that drugs and gambling stimulate the same biochemical pathways. Like drug addicts, gamblers' cognitive power is greatly diminished. 

Overeating, too, has been accused of being a behavioural addiction. Studying a group of compulsive overeaters, a research team led by Nora Volkow, a psychiatrist of Brookhaven National Laboratory, New York, uncovered low levels of dopamine receptor in their brains. 

Dopamine is a neurotransmitter that ferries information from one nerve cell to another via receptors that sit on the cell membrane. So, lack of dopamine receptor disrupts dopamine mediated communication. This brain anomaly robs a person of his ability to control overeating. 

"Bulimia, which is characterised by overeating and then vomiting, also looks a lot like an addiction," says Eric Hollander, a psychiatrist at Mount Sinai School of Medicine, New York. According to Patricia Faris, a gastrointestinal physiologist at the University of Minnesota, Minneapolis, like drug addiction, bulimic behaviour initially seems innocuous but slowly turns into compulsive behaviour due to changes in the brain's nerve cells. "Bulimia disturbs the vagus nerve, which plays a key role in regulating heart and lungs as well as the vomiting impulse," says Faris. "If one indulges in uncontrolled eating for a few years, it becomes an intractable problem." 

Indiscriminate sex is yet another agent of behavioural addiction. Some researchers are dubious about its role in behavioural addiction, but growing evidence suggests that indiscriminate sex may pave the way for addiction. Those who are obsessed with sex forget to put brakes on their quest for an elusive satisfaction. "Sex addicts resemble cocaine addicts and probably share with them a common defect in the nervous system," said Anna Rose Childress, a neurologist at the University of Pennsylvania in Philadelphia. 

Both in cocaine addicts and sex addicts, the brain's inhibition is over-ridden, as a result of which the person doesn't know when to stop, said Childress. To find an antidote for sex addicts, Childress has been studying sexual desire in normal subjects to find a 'stop' switch in their brains that halts sexual desire before it turns abnormal. Studies with normal subjects have shown that the brain's activity during sexual arousal resembles that of drug stimulation. 

"One problem that afflicts a great many women, in particular, is compulsive shopping," says Kim. Blinded by shopping frenzy, a compulsive shopper often turns up huge credit card bills. Feelings of depression and anxiety are common among compulsive shoppers. "The shopping itself can generate temporary drug-like highs before the shopper crashes into depression, guilt, anxiety and fatigue," explained Shaffer. "In my clinical experience, compulsive shoppers have withdrawal symptoms like drug addicts," he added. 

Apart from compulsive shopping, psychiatrists find that kleptomania (shoplifting or compulsive stealing) also leads to addiction. True kleptomaniacs steal things without bothering about their intrinsic value. 

But how does a 'healthy' activity like jogging become addictive behaviour? Jogging has been reported to raise the levels of chemicals similar to those found in drug addicts' brains. Stefan Brene, a psychiatrist at the Karolinska Institute, Stockholm, used rats to study its darker aspect. According to him, rats that are prone to addiction spend much more time on the running wheel than other rats do. Further tests revealed that running and consumption of cocaine triggered the same biochemical response in the brain. "This work shows that in an addiction prone rat, running can increase the preference for ethanol, indicating that a non drug addiction can stimulate the craving for drugs in the brain," says Brene. 

"One addiction debilitates the brain in such a way that it prepares the stage for the onset of another addiction," says Walter Kaye, who does research on eating disorders at the University of Pittsburgh Medical Centre. Statistics show that men are more prone to sex addiction and gambling than women, but ninety per cent of compulsive shoppers are women. 

To learn the mechanisms of addiction, scientists have started studying how normal subjects' brains respond to non drug stimuli. In a recent issue of Neuron, Hans Breiter and colleagues in Massachusetts General Hospital, Boston, submitted a paper on the brain responses of normal males to gambling. They write, "Blood flow in dopamine rich areas indicates that the same neural network is involved in the highs and lows of winning money, abusing drugs or anticipating a gastronomical treat." 

Thus, the long held notion that drugs are key to addiction has been dislodged. This finding opens a whole new field of research that may provide remedies for self-destructive behaviours.