Obsessions, compulsions span decades.

Each day, a girl washes her hands for hours at a time to destroy the bacteria that, she tells herself, accumulate when she touches doorknobs. A man stops his car and retraces his path after any minor bump in the road, fearing that he has run over someone. People such as these often feel tormented by their obsessive thoughts and compulsive acts but cannot resist them.

While the symptoms of what psychiatrists call obsessive-compulsive disorder (OCD) disrupt daily life with dramatic bluntness, the long-term outlook for sufferers of this condition remains poorly understood. A 40-year investigation now offers a rare glimpse at the natural course of the disorder in a group of individuals who, for the most part, received ho formal treatment.

A large majority of them exhibited substantial improvement, often within a decade of receiving an OCD diagnosis, hold Gunnar Skoog and Ingmar Skoog, psychiatrists at Sahlgrenska University Hospital in G6teborg, Sweden. However, only 1 in 5 individuals achieved full recovery; 1 in 3 continued to grapple with symptoms that interfered with their daily activities, and about 1 in 4 retained milder signs of the disorder.

A total of 144 people, all diagnosed with OCD at a psychiatric hospital between 1947 and 1953, participated in the study. Most were interviewed by Gunnar Skoog between 1954 and 1956 and again between 1989 and 1993; for 22, the second interview was with a close friend or family member and not the patient.

The study, published in the February Archives of General Psychiatry, contains several intriguing findings. People who developed obsessive-compulsive disorder before age 20, particularly males, had the worst prospects for improvement. Also, intermittent symptom flare-ups were the most commonly reported OCD pattern at the first interviews: at the second interview, participants most frequently cited symptoms that had lasted for at least 5 years.

Recovery within a few years of OCD's onset often heralded lasting gains but did not insulate patients against an eventual return of symptoms. Of 41 volunteers who had nearly or fully recovered from the disorder at the first interview, 20 maintained their improvement 3 decades later, while 8 had relapses after going largely without symptoms for more than 20 years.

Only 17 patients received a medication for OCD, clomipramine, that has become available in the past decade, its use significantly helped 10 of them.

"This study will serve as a benchmark in our efforts to understand and treat OCD," conclude psychiatrist Lawrence H. Price of Butler Hospital in Providence, R.I., and his coworkers in an editorial comment in the same journal.

Despite limitations in their data and sample, the Skoogs' findings will aid efforts to evaluate the effects of new medications on the natural progression of OCD, Price's group says.