In the study, 50 people newly-diagnosed with schizophrenia or related psychotic disorders with no other known risk factors were looked at. 16 percent either had diabetes or an abnormal rate of glucose metabolism, says Dr. Brian Kirkpatrick, MCG Department of Psychiatry and Health Behavior.
A control group of people without schizophrenia, similarly sized, contained none with signs of the disease. “These findings point toward there being some shared environmental factors or genetic factors between the development of schizophrenia and diabetes,” Dr. Kirkpatrick says.
Some of the more effective anti-psychotic medications are known to cause rapid weight gain, which is a risk factor for type 2 diabetes. A recent study, based on data from the Clinical Antipsychotic Trials of Intervention Effectiveness Schizophrenia Trial, showed prevalence rates of metabolic syndrome, a group of risk factors that include abdominal obesity, high lipid and cholesterol blood levels and insulin resistance, is more than 50 percent in women and about 37 percent in men with schizophrenia.
“Many people focus on the brain function part of the disease, but patients also have other medical problems that can’t be attributed to other factors,” Dr. Kirkpatrick says. “Bad things that happen in utero and at birth, such as prenatal famine and low birth weight, have both been shown to increase the risk of diabetes and schizophrenia. Problems in early development can leave a lasting impact.”
Establishing the link between the diseases may help scientists further understand the genetics of schizophrenia. “And that may eventually enable some sort of intervention strategy.”
The findings were presented at the International Congress on Schizophrenia Research in San Diego March 28-April 1 2009.
The link between schizophrenia and diabetes has been observed for over a century. It remains unclear, however, just what the underlying reasons are. Well over 100 papers have been published on the relationship between abnormal glucose metabolism and schizophrenia.
For example, one previous study(1) was done in Northern Ireland in 1986, to find out the rate of diabetes in long-stay patients in two psychiatric hospitals, and whether there was any association. It concluded that in fact there was a higher percentage of diabetics in the institutions than was expected, and that drug therapies may have had a contributing effect on the development of diabetes.
Diabetes is very common in the schizophrenia populations, even though most sufferers in their community go undiagnosed. It is generally agreed that the reasons why individuals with schizophrenia are more at risk for diabetes are most likely multifactorial.
1. Diabetes and Schizophrenia-a Preliminary study- HA McKee, PF D’arcy, PJK Wilson Journal of CIinicaI and Hospital Pharmacy (1986) 11,297-299 DOI 0.1111/j.1365-2710.1986.tb00855.x
Artwork: Chris Nurse, Wellcome Images, Creative Commons Attribution License.