Researchers have laid to rest
the myth that another mental disorder stems from
"bad parenting." A new study from Johns Hopkins
has shown that obsessive-compulsive disorder
(OCD), like schizophrenia and bipolar disorder,
tends to run in families and has a strong genetic
basis.
People with a first-degree relative with OCD --
brothers, sisters and parents -- have a five times
greater risk of having the illness themselves at
some time in their lives, according to results of
the study published in the April Archives of
General Psychiatry.
The researchers identified 80 patients with OCD
and 343 of their first-degree relatives and
compared them with 73 control patients without
mental illness and 300 of their relatives. The
results showed the strong familial link for the
most common form of the disorder, which strikes in
childhood.
Marked by persistent, intrusive, senseless
thoughts (obsessions) and repetitive behaviors
that can't be ignored (compulsions), OCD has been
called one of the 10 most disabling medical
conditions worldwide by the World Health
Organization.
It has also long evaded psychiatrists' attempts
to show that genes play a role in who gets the
disorder.
"We've known OCD as a psychiatric condition for
more than a century," says psychiatrist Gerald
Nestadt, M.D., who led the research team, "But
doubts have remained about the hereditary nature."
"There is surely some environmental aspect to
OCD," says Nestadt. "If your mother is constantly
washing her hands and worrying over it, that could
have an effect. But what's obvious to
investigators is that, in patients with affected
family members, their behavior isn't necessarily
the same as the family member's. A patient whose
mother washed her hands might, for example, have
to check light switches over and over. They both
have an obsession, but their behavior is
different. And that points to a biological basis."
Psychiatric studies where researchers must
evaluate large numbers of people often suffer from
the common bugaboo of unintentional bias, Nestadt
says. This may be a reason behind inconclusive
results of earlier studies that tried to link
heredity and OCD.
This current research, he says, used patients
from different clinics, in order to avoid
institutional bias. Diagnosing researchers were
blinded as to a patient's condition.
The study opens the door to the next step,
identifying the actual gene(s) involved, says
Nestadt.
OCD affects as high as 3 percent of the world's
population. Although it touches all ages, the
period of greatest risk is from childhood to
middle age.
Twin studies have shown identical twins have a
higher incidence of OCD -- almost 90 percent --
than fraternal twins, where the odds of both
having the disorder is close to 50 percent.
Other researchers are Jack Samuels, Ph.D., Mark
Riddle, M.D., O. Joseph Bienvenu III, M.D.,
Kung-Yee Liang, Ph.D., Michele LaBuda, Ph.D., John
Walkup, M.D., Marco Grados, M.D., and Rudolph
Hoehn-Saric, M.D.
The study was funded by NIH grants.
Related website:
OCD
Family Study
[Contact: Marjorie
Centofanti ]
21-Apr-2000