Low dopamine levels behind relapse to smoking

Washington - A new study has suggested that low dopamine levels that occur as a result of withdrawal from smoking actually promote the relapse to smoking.
 
Dopamine is a brain chemical messenger that is critically important in reward and motivation. Some research suggests that one of its central roles is to send a signal to the brain to ‘seek something enjoyable’.

Indeed, dopamine is released during many rewarding experiences, including taking drugs, smoking, having sex, and eating food.

This signal seems to depend on the dopamine, which is released in response to environmental cues, called phasic release, as opposed to the tonic seepage of small amounts of dopamine from nerve cells.

The tonic release of dopamine is implicated in helping the dopamine system set the level of its reactivity to inputs.

Since dopamine is released by smoking, it makes sense that dopamine levels become abnormal when a smoker chooses to stop smoking. Researchers from Baylor College of Medicine in Texas undertook their study to characterize these changes.

They studied mice that were administered nicotine, the active constituent of cigarettes, for several weeks. The researchers then withheld the nicotine and measured the subsequent alterations in dopamine signaling during the withdrawal period.

They reported that withdrawal from nicotine produced a deficit in dopamine in which the basal dopamine concentration and tonic dopamine signals were disproportionately lower than the phasic dopamine signals. Re-exposure to nicotine reversed the hypodopaminergic state.

According to the authors, these findings indicate that medications, which could help elevate tonic dopamine levels during withdrawal, may be successful treatment strategies for nicotine-dependent individuals attempting to quit smoking.

Theoretically, such a treatment could help normalize any fluctuating dopamine levels from the sudden lack of nicotine, and also lessen the dopamine-influenced urges to seek out the nicotine, leading to relapse.

The study appeared this month in Biological Psychiatry.