The first generation of antipsychotic medications, known as the typical antipsychotics, has demonstrated great effectiveness in treating a variety of mental health issues. Schizophrenia is the most frequent cause for the prescription of a typical antipsychotic. These typical antipsychotics also cause a variety of side effects, including sleep disturbances and movement disorders.
Tremors and loss of muscle tone can sometimes become so severe that patients have to discontinue treatment. More recently, the atypical antipsychotics have offered the same clinical results with fewer side effects. However, the side effects that can occur with this class of medications are troubling in their own right.
Although the reasons aren’t clear, atypical antipsychotics can lead to serious metabolic side effects. Prolonged use of these medications can result in obesity and even diabetes. Zyprexa (olanzapine) has the greatest risk of causing harmful metabolic effects. Previous research has indicated that a little-understood relationship between atypical antipsychotics, glucose, and insulin is responsible for weight gain and fat accumulation in those who take atypical antipsychotics.
At Penn State University, researchers conducted a study with live rats to better understand how and why antipsychotic medications lead to changes in human metabolism. One group of rats received daily Zyprexa for several weeks, while another group had a single, acute dose of the drug. The rats given the single dose exhibited an almost immediate drop in their activity levels, without a matching decrease in food intake.
In essence, these rats took in more nutrition than necessary. At the same time, significant changes to insulin meant that the extra calories were converted into fat stores. The acute responses were also observed in the chronically-dosed rats. Surprisingly, the rats did not all gain significant amounts of weight. Still, the body composition of these rats changed in drastic way whether they gained weight or not. Fatty tissue as a proportion of body weight increased steadily for the first three weeks of the study before plateauing. Similar effects have been observed in humans in small studies.
Measurable and significant weight gain is the primary concern when prescribing an atypical antipsychotic. It is arguably the most serious side effect, as increased body mass raises the risk of numerous chronic health problems. However, the rat study at Penn State showed that even without large weight gains, body composition can change in distinctly unhealthy ways. More fatty tissue leads to altered hormone levels and potentially more plaque in the blood stream. This study makes a strong case that patients taking atypical antipsychotics, especially Zyprexa, should have regular blood work to ensure healthy insulin and glucose levels.
- Albaugh, V.L., Judson, J.G., She, P., Lang, C.H., Maresca, K.P., Joyal, J.L, and Lynch, C.J. (2011). Olanzapine promotes fat accumulation in male rats by decreasing physical activity, repartitioning energy and increasing adipose tissue lipogenesis while impairing lipolysis. Molecular Psychiatry, 16, (5), 569-581.
- Olanzapine – PubMed Health. (n.d.). National Center for Biotechnology Information. Retrieved from http://www.ncbi.nlm.nih.gov/pubmedhealth/PMH0000161/
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