Dissecting
the relationship between schizophrenia and an increased risk of type 2 diabetes
has physician- scientists reaching across the Atlantic Ocean.They are looking at newly diagnosed schizophrenics in a Spanish community to gauge schizophrenics’ risk of diabetes.
Scientists know the drugs that best control psychosis increase the risk. “We know it’s the medicine; I’m asking whether it’s the disease as well,” says Dr. Brian Kirkpatrick, vice chair of the Medical College of Georgia Department of Psychiatry and Health Behavior and principal investigator on the National Institute of Diabetes & Digestive & Kidney Diseases-funded study.
Dr. Kirkpatrick and colleagues at Hospital Clinic at the University of Barcelona in Spain and the University of Maryland note mounting evidence that developmental problems resulting from significant maternal stress in the second or early third trimester of pregnancy may cause schizophrenia and related problems.
“The brain has this incredibly complex development where cells are born here and march over here and send communication over here; [in schizophrenics,] this goes wrong from the very beginning probably,” Dr. Kirkpatrick says. “If you look at the brain under a microscope, at first blush, it looks pretty normal, but there are subtle differences.”
Schizophrenia symptoms can include memory and attention problems, wide palates and subtle abnormalities of fingertips, ear shape and peripheral muscle nerves. Psychotic symptoms typically start in late adolescence or early adulthood. “Although psychosis is what we often treat, it’s just part of the problem,” says Dr. Kirkpatrick.
Researchers believe the developmental abnormalities also increase the risk of diabetes. One recent study, based on data from the Clinical Antipsychotic Trials of Intervention Effectiveness Schizophrenia Trial, showed that about 50 percent of female schizophrenics and 37 percent of male schizophrenics have metabolic syndrome, a group of risk factors that includes abdominal obesity, high lipid and cholesterol blood levels and insulin resistance.
Dr.
Kirkpatrick has a chart of weight gain based on drugs used to treat psychosis
that resembles a stairway to disaster. Patients on olanzapine and clozapine,
two of the most effective anti-psychotics, gained about 10 pounds within a few
weeks. While weight gain is a major risk factor for type 2 diabetes, previous
studies have shown the disease also can appear in schizophrenics shortly after
they begin treatment and without weight gain.
Studies predating anti-psychotics also have shown schizophrenics have an increased rate of impaired glucose tolerance or insulin resistance, a hallmark of diabetes. “It’s not 100 percent; it just changes your risk. Bad things in utero increase the risk of diabetes and the risk of schizophrenia. It may be they are going to be associated because the same bad things cause both,” says Dr. Kirkpatrick.
In the study, researchers are comparing glucose tolerance in newly diagnosed schizophrenics to that of healthy people as well as those with untreated depression and those with a recent major crisis. All except the healthy group should have increased levels of cortisol, a stress hormone that can mimic diabetes by increasing insulin resistance.
The Esquerra Eixample neighborhood in Barcelona was selected as a primary study site because it has a fairly homogenous population and researchers can study patients early in the illness.
Patient enrollment began in 2005 and researchers hope to enroll 82 people in each arm of the study. After initial testing, schizophrenics will receive olanzapine and be followed. Researchers hope to glean measures clinicians can easily use to predict development of insulin resistance with anti-psychotic treatment. Greater insulin resistance prior to treatment may be the measure, Dr. Kirkpatrick says.
-Toni Baker