Pseudoparadoxical impulsivity in restrictive anorexia nervosa: a consequence of the logic of scarcity.

OBJECTIVE

To explain an apparently paradoxical pattern wherein sufferers of restrictive anorexia nervosa exhibit both rigorous self-restraint and episodic impulsivity.

METHOD

The experimental, historical, and clinical literatures were examined for evidence of psychological and behavioral changes accompanying severe dietary constriction; such changes were noted and compared with those reported to occur in anorexics.

RESULTS

Increased impulsivity in association with dietary constriction is described in diverse literatures. A number of lines of evidence suggest that the serotonergic system mediates this change.

DISCUSSION

Many forms of impulsivity can be understood as having once constituted fitness-enhancing responses to resource scarcity. It is suggested that an evolved psychological mechanism calibrates the individual's sensitivity to risk in light of future prospects. Self-injurious behaviors are explicable as misfirings of such a mechanism. Similarly, excessive exercising by anorexics may reflect the misdirection of reward systems that normally encourage adaptive increases in ranging behavior under conditions of scarcity.