A new study suggests, if schizophrenia runs in a family, bipolar disorder most likely does as well (and vice versa). The study, published online in the January issue of the journal The Lancet, suggests both disorders share common genetic causes.
Whether schizophrenia and bipolar disorder are two distinct disorders or more connected – has been the forefront of a century long debate among the psychiatric community.
Some patients, over the duration of their illness, experience symptoms characteristic of both disorders, such as manic mood swings associated in bipolar disorder and psychosis associated in schizophrenia.
Recent genetic studies have suggested a common genetic cause for both conditions. But previous studies in families have not supported such conclusions, finding no increase in bipolar disorder in family members with schizophrenia.
Schizophrenia is a chronic, severe and disabling brain disorder that affects an estimated 1.1 percent of the U.S. population age 18 and older in any given year, according to the NIMH.
The disease tends to start in late adolescence or early adulthood. It can stay with an individual for a lifetime, despite treatment. Schizophrenia may affect one in every 100 people at some point in their life.
Bipolar disorder, known also as manic-depressive illness, is a brain disorder that causes unusual shifts in a person’s mood, energy, and ability to function. An estimated 5.7 million American adults or 2.6 percent of the population age 18 and older in any given year, have bipolar disorder.
A study of 9 million Swedish people over a period of 30-years found close relatives of people with bipolar disorder or schizophrenia had a greater risk of both disorders, while evidence from half-siblings suggested the effect was due mainly to genetic factors.
The findings identified 36,000 people with schizophrenia and 40,500 people with bipolar disorder.
“We found evidence that suggests bipolar disorder and schizophrenia share a common genetic cause,” Paul Lichtenstein and colleagues at Karolinska Institute in Stockholm reported. ”The results challenge current disease classification between schizophrenia and bipolar disease, and are consistent with a reappraisal of these disorders as distinct diagnostic entities.”
Nick Craddick and Michael Owen, MD, PhD of the University of Cardiff, Britain, said the findings underscore the need to reappraise psychopathology.
An earlier study, in July, suggested a specific gene variation may contribute to schizophrenia.
The research, published in two online journals, represents some of the strongest genetic links ever found to the cause of schizophrenia.
Researchers believe these findings open up a new era in the field and will likely lead to the development of new drugs, improved diagnosis, and preventative therapies.
Widely used anti-psychotic drugs, such as AstraZeneca’s Seroquel and Eli Lilly’s Zyprexa have side effects that can include muscle rigidity and weight gain. #