Food intake and reward mechanisms in patients with schizophrenia: implications for metabolic disturbances and treatment with second-generation antipsychotic agents

New insights into symptoms and neurocircuit function of anorexia nervosa

Individuals with anorexia nervosa have a relentless preoccupation with dieting and weight loss that results in severe emaciation and sometimes death. It is controversial whether such symptoms are secondary to psychosocial influences, are a consequence of obsessions and anxiety or reflect a primary disturbance of brain appetitive circuits. New brain imaging technology provides insights into ventral and dorsal neural circuit dysfunction - perhaps related to altered serotonin and dopamine metabolism - that contributes to the puzzling symptoms found in people with eating disorders. For example, altered insula activity could explain interoceptive dysfunction, and altered striatal activity might shed light on altered reward modulation in people with anorexia nervosa.

Obesity, serious mental illness and antipsychotic drugs

The prevalence of overweight and obesity is higher in people with mental illness than in the general population. Body weight is tightly regulated by a complex system involving the cortex and limbic system, the hypothalamus and the gastrointestinal tract. While there are justifiable concerns about the weight gain associated with antipsychotic medication, it is too simplistic to ascribe all obesity in people with serious mental illness (SMI) to their drug treatment. The development of obesity in SMI results from the complex interaction of the genotype and environment of the person with mental illness, the mental illness itself and antipsychotic medication. There are dysfunctional reward mechanisms in SMI that may contribute to poor food choices and overeating. While it is clear that antipsychotics have profound effects to stimulate appetite, no one receptor interaction provides an adequate explanation for this effect, and many mechanisms are likely to be involved. The complexity of the system regulating body weight allows us to start to understand why some individuals appear much more prone to weight gain and obesity than others.

Metabolic syndrome in people with schizophrenia: a review

Metabolic syndrome and other cardiovascular risk factors are highly prevalent in people with schizophrenia. Patients are at risk for premature mortality and overall have limited access to physical health care. In part these cardio-metabolic risk factors are attributable to unhealthy lifestyle, including poor diet and sedentary behaviour. But over recent years it has become apparent that antipsychotic agents can have a negative impact on some of the modifiable risk factors. The psychiatrist needs to be aware of the potential metabolic side effects of antipsychotic medication and to include them in the risk/benefit assessment when choosing a specific antipsychotic. He should also be responsible for the implementation of the necessary screening assessments and referral for treatment of any physical illness. Multidisciplinary assessment of psychiatric and medical conditions is needed. The somatic treatments offered to people with severe and enduring mental illness should be at par with general health care in the non-psychiatrically ill population.

Zonisamide prevents olanzapine-associated hyperphagia, weight gain, and elevated blood glucose in rats

Olanzapine (OLZ), one of the second-generation atypical antipsychotics (SGAs), has shown relative advantages in patient adherence and outcomes. However, OLZ has also been associated with a higher incidence of weight gain than most other SGAs. Excessive weight gain may in turn contribute to long-term health concerns for some individuals. Zonisamide (ZNS), a medication approved in the United States as an adjunct in the management of epilepsy, has a diverse pharmacological profile, including sodium channel blockade, monoamine enhancement, and inhibition of carbonic anhydrase. ZNS has also been reported to cause weight loss in both humans and rodents. We hypothesized that this profile might be beneficial when co-administered with OLZ. To test this hypothesis, we evaluated the effects of OLZ on body weight, as well as the pathways known to regulate feeding behavior and arousal in the Sprague-Dawley rat. As indicated via c-Fos expression, we found an OLZ-induced activation in the nucleus accumbens and orexin neurons in the lateral hypothalamus. An OLZ-associated development of hyperphagia, weight gain and elevated blood glucose in the rat was also found. These outcomes were attenuated and reversed in the presence of concomitant ZNS. These results suggest the hypothesis that ZNS may effectively treat or prevent weight gain or metabolic changes associated with the SGAs. Future studies of this combination in patients through appropriately designed human clinical studies are encouraged.

Effects of olanzapine and ziprasidone on glucose tolerance in healthy volunteers

Atypical antipsychotics have been linked to a higher risk for glucose intolerance, and consequentially the development of type 2 diabetes mellitus (DM2). We have therefore set out to investigate the acute effects of oral administration of olanzapine and ziprasidone on whole body insulin sensitivity in healthy subjects. Using the standardized hyperinsulinemic euglycemic clamp technique we compared whole body insulin sensitivity of 29 healthy male volunteers after oral intake of either olanzapine 10 mg/day (n = 14) or ziprasidone 80 mg/day (n = 15) for 10 days. A significant decrease (p<0.001) in whole body insulin sensitivity from 5.7 ml/h/kg ( = mean, SM = 0.4 ml/h/kg) at baseline to 4.7 ml/h/kg ( = mean, SM = 0.3 ml/h/kg) after oral intake of olanzapine (10 mg/day) for 10 days was observed. The ziprasidone (80 mg/day) group did not show any significant difference (5.2+/-0.3 ml/h/kg baseline vs 5.1+/-0.3 ml/h/kg) after 10 days of oral intake. Our main finding demonstrates that oral administration of olanzapine but not ziprasidone leads to a decrease in whole body insulin sensitivity in response to a hyperinsulinemic euglycemic challenge. Our finding is suggestive that not all atypical antipsychotics cause acute direct effects on glucose disposal and that accurate determination of side effect profile should be performed when choosing an atypical antipsychotic.

Effect of antipsychotics on peptides involved in energy balance in drug-naive psychotic patients after 1 year of treatment

Weight gain has become one of the most common and concerning side effects of antipsychotic treatment. The mechanisms whereby antipsychotics induce weight gain are not known. It has been suggested that peptides related to food intake and energy balance could play a role in weight gain secondary to antipsychotic therapy. To better understand the pathophysiology of antipsychotic-induced weight gain, we studied the effects of 3 antipsychotic drugs (haloperidol, olanzapine, and risperidone) on peptides involved in energy balance (insulin, ghrelin, leptin, adiponectin, visfatin, and resistin) in a population of drug-naive patients with first episode of psychosis.A significant increase in weight (10.16 kg [SD, 8.30 kg]; P < 0.001), body mass index (3.56 kg/m [SD, 2.89 kg/m]; P < 0.001), and fasting insulin (3.93 muU/mL [SD, 3.93 muU/mL]; P = 0.028), leptin (6.76 ng/mL [SD, 7.21 ng/mL]; P < 0.001), and ghrelin (15.47 fmol/mL [SD, 47.90 fmol/mL]; P = 0.009) plasma levels were observed. The increments in insulin and leptin concentrations were highly correlated with the increment in weight and body mass index and seem to be a consequence of the higher fat stores. The unexpected increase in ghrelin levels might be related with the causal mechanism of weight gain induced by antipsychotics. Finally, the 3 antipsychotics had similar effects in all parameters evaluated.

Metformin for metabolic dysregulation in schizophrenic patients treated with olanzapine

The second generation antipsychotic drugs, such as risperidone, olanzapine, and quetiapine, are effective in treating patients with schizophrenia and have been considered as the first line therapy. Recently, increasing attention has been drawn to the potential diabetogenic effect of these novel antipsychotics. The goal of this study was to evaluate the effect of metformin treatment on the olanzapine-induced metabolic disturbance in schizophrenic patients. Twenty-four schizophrenic subjects who had received olanzapine treatment at least 3 months were assigned to the therapy with metformin 1500 mg/day for 8 weeks. The metabolic parameters were quantitatively assessed at baseline, weeks 2, 4, and 8 by using the intravenous glucose tolerance test. After an 8-week treatment with metformin, the body weight, fasting levels of glucose, triglyceride, and insulin, insulin secretion, and insulin resistance significantly decreased. Half of study subjects with metabolic syndrome obtained improvement after the metformin trial. Subjects' psychopathological condition remained unchanged during the study period. The olanzapine-induced metabolic disturbance could be reversed after 8-week metformin treatment. Based on the results of this study, we hypothesize that metformin could modulate the effect of olanzapine-induced metabolic disturbance.

Gender differences in the motivational processing of facial beauty

Gender may be involved in the motivational processing of facial beauty. This study applied a behavioral probe, known to activate brain motivational regions, to healthy heterosexual subjects. Matched samples of men and women were administered two tasks: (a) key pressing to change the viewing time of average or beautiful female or male facial images, and (b) rating the attractiveness of these images. Men expended more effort (via the key-press task) to extend the viewing time of the beautiful female faces. Women displayed similarly increased effort for beautiful male and female images, but the magnitude of this effort was substantially lower than that of men for beautiful females. Heterosexual facial attractiveness ratings were comparable in both groups. These findings demonstrate heterosexual specificity of facial motivational targets for men, but not for women. Moreover, heightened drive for the pursuit of heterosexual beauty in the face of regular valuational assessments, displayed by men, suggests a gender-specific incentive sensitization phenomenon.

Ingenuity pathway analysis of clozapine-induced obesity

BACKGROUND

Lipid accretion is one of the major side effects of clozapine pharmacotherapy of schizophrenia that made clozapine into an interesting obesity drug model.

METHOD

Ingenuity Pathway Analysis (IPA) engine was used for core analysis and building the networks of weight regulation.

RESULTS

The examination of molecules that were selected into 'clozapine neighborhood' identified them as multifunctional signals that appear to orchestrate vascular and tissue functions plausibly implicated in adiposity side effect.

CONCLUSIONS

It is hypothesized that clozapine unmasks the functional and morphological phenotype of microvascular deficit that facilitates shunting nutrients from utilization toward storage.

Reaching for wellness in schizophrenia

Coronary heart disease (CHD) is a major cause of mortality in people who have schizophrenia, and it is caused by many factors relating to lifestyle choices, antipsychotic treatment, and other medical comorbidities. This article focuses on modifiable risk factors such as cigarette smoking, diabetes, hyperlipidemia, hypertension, and the metabolic syndrome, all of which occur more frequently in patients who have schizophrenia than in the general population. Although treatment of risk factors for CHD is still far from ideal, all attempts should be made to strive for wellness to improve patients' long-term outcomes.

Attenuating effect of reboxetine on appetite and weight gain in olanzapine-treated schizophrenia patients: a double-blind placebo-controlled study

RATIONALE

Search for safe and effective strategies to diminish weight gain associated with second generation antipsychotics (SGAs) is imperative. In the present study, we sought to replicate our preliminary findings, which indicated that coadministration of the selective norepinephrine reuptake inhibitor reboxetine attenuates olanzapine-induced weight gain.

MATERIALS AND METHOD

Fifty-nine patients hospitalized for first-episode DSM-IV schizophrenic disorder participated in this randomized double-blind study. Reboxetine (4 mg/day; 31 patients) or placebo (29 patients) was coadministered with olanzapine (10 mg/day) for 6 weeks. Analysis was by intention-to-treat.

RESULTS

Nine patients in each group prematurely discontinued the trial. Olanzapine/reboxetine-treated patients showed a significantly lower increase in body weight (mean = 3.31 kg, SD = 2.73) than their olanzapine/placebo-treated counterparts (mean = 4.91 kg, SD = 2.45). Significantly fewer olanzapine/reboxetine-treated patients gained at least 7% of their initial weight, the cutoff for clinically significant weight gain (6 [19.4%] of 31 patients vs 13 [46.4%] of 28 patients). Seven (22.6%) olanzapine/reboxetine-treated patients compared to only one patient (3.6%) in the olanzapine/placebo group revealed no weight change or even modest weight loss. Appetite increase was significantly lower in the olanzapine/reboxetine than olanzapine/placebo group and was correlated with attenuation of weight gain. Reboxetine addition was safe and well tolerated.

CONCLUSIONS

The results confirm that coadministration of reboxetine promotes a clinically meaningful attenuation of olanzapine-induced weight gain in schizophrenia patients. If substantiated in long-term studies, along with behavioral management and diet counseling, reboxetine may have a clinical utility in controlling SGA-induced weight gain.