The New Biology Of Obsessive-Compulsive Disorder: Implications for Evolutionary Psychology

PERSPECTIVES IN BIOLOGY AND MEDICINE Volume 41 ¦ Number 2 ¦ Winter 1998 THE NEW BIOLOGY OF OBSESSIVE-COMPULSIVE DISORDER: IMPLICATIONS FOR EVOLUTIONARY PSYCHOLOGY JUDITH L. RAPOPOPiT* and ALAN FISKEf Obsessive compulsive disorder (OCD) is a chronic psychiatric disease in which thoughts and habits run wild. Obsessive thoughts such as unreasonable doubts (am I a bad person? did I lock the door? do I have AIDS? did I harm someone?) or compulsive habits (praying, repeating, ordering, checking, cleaning, or washing) consume hours of the patients' time [I]. Typically, sufferers are aware that these symptoms are "crazy" but cannot control them. The ritualistic nature of OCD symptoms is striking. Repetitive counting or washing is accompanied by a sense that these behaviors are necessary to ward off discomfort or danger. Some OCD patients have commented on the similarity between their new and peculiar thoughts and behaviors and religious rituals or magical practices of other cultures. If the epidemiological studies are correct, as many as 2 million people in the United States have this disorder [2]. Until recently, most sufferers kept their disorder secret because of the embarrassment over the bizarre and irrational nature of their thoughts and rituals. The public awareness of the probable neurological nature of the disorder and the availability of effective treatments has increased recognition and referral of OCD patients . The last two decades of research have greatly advanced our understandCorrespondence : National Institute of Mental Health, Child Psychiatry Branch, Building 10, Room 3N202, fO Center Drive, Bethesda, MD 20892. *National Institute of Mental Health, Child Psychiatry Branch. "("Department of Anthropology, University of California at Los Angeles, Box 951553.© 1998 by The University of Chicago. All rights reserved. 0031-5982/98/4102-1055$01.00 Perspectives in Biology and Medicine, 41, 2 ¦ Winter 1998 159 ing of OCD, which now is possibly the psychiatric syndrome for which there is the most specific and convincing information on the neural circuitry mediating the underlying abnormal behaviors. Diverse lines of evidence indicate that dysfunction of cortical-basal ganglia circuitry underlies OCD. This raises important questions about the evolutionary basis for neural control of these behaviors. The existence of such specificity in the "hard wiring " of human behaviors as basic to everyday functions as cleaning, checking , and ordering, or concern about dangers to self or others, suggests a biological basis for universal categories of certain thoughts and rituals. The notion of psychiatric disorder asjust another part of medical biology is nothing new. However, some of the symptoms ofOCD—such as excessive prayer, ordering and counting, over-scrupulous concern about acceptable behavior, pollution, and purity, and rituals resembling imitative magic— are generally assumed to be culturally mediated and not thought to be so closely tied to specific brain circuitry. If there is a strong biological component , then the identity of these categories, their breadth, and how their mediating circuitry came to exist are exciting and researchable questions. The debates over such conceptualizations extend beyond psychiatry and medicine to touch linguistics, psychology, anthropology, and evolutionary biology. The recent advances in the neurobiology ofOCD, with converging evidence from genetics, brain imaging, immunology, and epidemiology, now suggest empirical research on the universality of fundamental types of human action, and on the joint role of biology and culture in shaping such complex actions. This paper will review recent biological and anthropological studies of OCD in order to suggest ways in which the study of disease may illuminate some fundamental issues in the social and behavioral sciences. Biological Research on Obsessive Compulsive Disorder PHARMACOLOGY The new look at OCD began with studies showing that clomipramine, a tricyclic drug with average antidepressant and antianxiety effects, had unique efficacy in treating OCD [3, 4] . This medication, and the four others to date that are equally effective anti-obsessional treatments, have in common their ability to block the reuptake of serotonin by brain neurons, with relatively little effect on norepinephrine reuptake. More recently, more selective serotonin reuptake inhibitors have become the drugs of choice for this disorder because a large percent of patients can tolerate their side effects [5] . The efficacy of these serotonergic drugs (and lack of efficacy of antidepressants that block reuptake of norepinephrine) inspired a "serotonin hypothesis" of OCD [6]. However, the...