Dr Citrome is Clinical Professor of Psychiatry and Behavioral Sciences, New York Medical College, Valhalla, NY.
Editor’s Note: We are pleased to present this Q&A with Leslie Citrome, MD, MPH, based on his presentation at the 2017 Psychiatric Congress, “Weight Gain and Metabolic Abnormalities in Patients with Schizophrenia.”
Patients with schizophrenia are at high risk for weight gain and metabolic abnormalities. There are many factors that contribute to this, including genetic predisposition to metabolic abnormalities, environmental factors such as poor diet, lack of exercise, cigarette smoking, and iatrogenic considerations such as exposure to medications that can lead to further disruption of metabolic health.
Q: What is metabolic syndrome?
A: Metabolic syndrome (MetS) is a public health concept also referred to as “Syndrome X” or “Insulin Resistance Syndrome.” MetS describes a cluster of cardiovascular disease risk factors and metabolic alterations associated with excess fat weight. MetS has been compared to cigarette smoking as an equal risk partner to premature coronary heart disease. The concept of MetS serves as a starting point for clinical interventions known to reduce risk for obesity-related type 2 diabetes, cardiovascular disease, and perhaps even cancer.
Q: What are the criteria for MetS?
A: The most commonly used US criteria are from the Third Report of the National Cholesterol Education Program Expert Panel on Detection, Evaluation, and Treatment of High Blood Cholesterol in Adults: Adult Treatment Panel III (ATP III). The ATP III criteria include meeting at least 3 of the following:
1. Abdominal obesity: waist circumference: men > 40 in; women > 88 cm 35 in;
2. High triglycerides blood levels: ≥ 150 mg/dL;
3. Low HDL-cholesterol blood levels: men < 40 mg/dL; women < 50 mg/dL;
4. High blood pressure: ≥ 130/85 mm Hg);
5. High fasting blood glucose (≥ 100 mg/dL.
Note that microalbuminuria is not included in ATP III criteria although it is in others.
Q: How do I assess MetS in the office?
A: Abdominal obesity is measured with a tape measure; we usually measure body weight as a proxy, but keep in mind that muscle weighs more than fat. A body mass index greater than 30 kg/m2 defines obesity. Getting blood work done (especially fasting) can be challenging, but one of the important clinical benefits of doing it early is that elevation of triglycerides can occur before substantial weight gain has accumulated. HbA1c can also be used for screening and does not require fasting. Blood pressure is now easier to obtain than ever before, given the availability of inexpensive automated blood pressure measuring devices.
Q: How common is MetS in people with schizophrenia?
A: In the Clinical Antipsychotic Trials of Intervention Effectiveness (CATIE) for schizophrenia, MetS was present in 30% of all participants. This is higher than in the general population. It has been estimated that patients with schizophrenia have a 3-fold greater risk for MetS than the general population.
Q: What are the consequences of MetS?
A: MetS is associated with a 4-fold relative risk for diabetes (in the general population); and with an approximate 2-fold risk for coronary heart disease, stroke, and premature mortality (in the general population).
Of additional interest is that MetS is significantly associated with cognitive impairment in schizophrenia and can potentially contribute to the functional decline observed in some patients with schizophrenia throughout the course of illness.
Q: What is the prevalence of type 2 diabetes mellitus in people with schizophrenia?
A: The prevalence of diabetes in persons with severe mental disorders is 2- to 3-fold higher than in the general population. The incidence of diabetes is also higher and the onset of diabetes appears to be 10 to 20 years earlier than in the general population.
The number of persons with diabetes mellitus has increased over the years. In a study of New York State hospitals, prevalence increased from 6.9% of 10,091 patients in 1997 to 14.5% of 7420 patients in 2004; incidence of newly treated diabetes increased from 0.9% in 1997 to 1.8% in 2004.
Diabetes is uncommon in young healthy adults, so it is important to note that the increased relative risk of diabetes is greatest in adolescents and young adults with severe mental disorders.
Q: Are genetic factors important in the development of diabetes mellitus?
A: Both schizophrenia and diabetes mellitus are highly heritable disorders. Recent studies have identified at least 37 common genes that increase the risk of both diabetes and schizophrenia. Approximately 11% and 14% of these risk genes for diabetes and schizophrenia, respectively, may account for the risk of the other disease. In addition to affecting an individual’s risk for diabetes directly, genetic polymorphisms in various genes, may also affect the risk of weight gain.
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