Prevalence of weight gain is a common in psychotic patients. Individuals with schizophrenia have more intra-abdominal fat. Therefore, these patients are at greater risk of complications of obesity. There are several lifestyle factors such as poor diet, smoking and a sedentary lifestyle which further increase its risk. Prevalence of obesity and metabolic disturbances has increased significantly after the discovery of atypical antipsychotics.
Weight gain is associated with significant physical and psychological diseases. Weight gain increases the risk of diabetes, cardiovascular disease and stroke. Coronary heart disease risk and metabolic syndrome is commonly prevalent in patients that are treated with antipsychotics. Obesity is associated with depression, low self-esteem, guilt and shame. Weight gain impaired quality of life and increases the risk of depression. It is also associated with noncompliance of medication as well
Weight gain induced by Antipsychotics is a complex side-effect with several mechanisms.
Weight gain is caused by a reduced rate of energy expenditure. This shows that weight management strategies should focus to increase energy consumption by exercise rather than strategies to reduce energy intake e.g. diet or food intake. One of the reason of weight gain with antipsychotics is associated with increased food intake and sedentary lifestyle.
The two receptors that are most associated with weight gain are
Serotonin transmission reduces food intake. On the other hand, antagonism of serotonin receptors induces food intake in spite of satiety leading to weight gain.
Histamine receptor antagonism increases energy intake centrally by increasing appetite.
The weight gain with antipsychotic is dependent on the affinity of these drugs with serotonin and histamine receptors. Clozapine and olanzapine have the greatest affinity for 5-HT2C and H1 receptor, that why they have greatest potential for weight gain. In contrast, risperidone has lesser affinity for the 5-HT2C and H1 receptors and thus has lesser chances of weight gain than olanzapine or clozapine.
There are certain fundamental biological factors that make some patients more prone to weight gain. Patients having low Body Mass Index are at greater risk of weight gain and that early. In the first few weeks of treatment, rapid weight gain predicts long-term weight gain. Sometimes, the weight gain is irreversible and even discontinuation or switching antipsychotics therapy does not reduce weight. A 5-HT2C receptormpolymorphism has strong associations with weight gain and increased risk of metabolic syndrome in people taking antipsychotics.
Other mechanisms include the effect of antipsychotics in increasing prolactin. Hyperprolactinemia can affect circulating levels of gonadal hormones and impair insulin sensitivity that leads to weight gain.
Hyperlipidemia and Hyperglycemia are often thought to be result of weight gain. There is independent associations of antipsychoticswith hyperglycemia and dyslipidemia. Olanzapine and clozapinehave the greatest impact in increasing blood glucose and lipids independent of adiposity. Psychosis and antipsychotics are both independently linked with an increased risk of diabetes and worsening blood sugar control. Atypical antipsychotics are more likely to produce this effect than the first-generation antipsychoticagents.
Management strategies are divided into choice of antipsychotic, pharmacological and psychological treatments for promoting weight loss and switching strategies.
The most important parameter in the prevention of weight gain is the choice of antipsychotic but optimal treatment of psychosis is a priority. There are a number of factors that should be considered when choosing an antipsychotic, which includes
The main pharmacological agents investigated for antipsychotic-induced weight gain are H2 receptor antagonists, topiramate, amantadine, metformin, antidepressants, fenfluramine and phenylpropanolamine.
Orlistat, sibutramine and rimonabant are effective in weight reduction. Orlistat is a lipase inhibitor which reduces the absorption of dietary fat.
The main psychological strategies in antipsychotic induced weight gain are
Psychological strategies may result in weight loss. The most important are behavioural interventions that emphasizes on lifestyle modifications and physical activity.
One option to reverse weight gain is to switch antipsychotics with a lower propensity to cause weight gain or dyslipidemia caused by previous antipsychotic treatment. Switching to ziprasidone is an effective strategy in individuals on olanzapine and produced reductions in lipids and weight.
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