A metabolic basis for drug dependence

In man, incessant, compulsive sexual activity may follow an increase in brain serotonin simultaneously with a decrease in brain noradrenalin. In animals a similar compulsive aphrodisiac effect on behaviour can occur with the use of an antiserotonin drug permitting a relative increase in noradrenalin.

Five commonly used drugs of dependence, including morphine, have been shown to increase brain serotonin, thus disturbing the ratio of this monoamine, to noradrenalin.

It is argued that drug dependence is a phenomenon of learning and that this learning depends upon stimulation of the reward system of the lateral hypothalamus, medial forebrain bundle and midbrain reticular formation. Drug dependence could follow if the balance of brain serotonin and noradrenalin were seriously disturbed by the drug in either direction. It is suggested that normalization of this metabolic balance might be a logical goal for treatment in drug addiction.