Low-fat oxidation may be a factor in obesity among men with schizophrenia

The resting metabolic rate of people with severe mental illness: a systematic review and meta-analysis

People with severe mental illness (SMI), including schizophrenia and related psychoses and bipolar disorder, are at greater risk for obesity compared with people without mental illness. An altered resting metabolic rate (RMR) may be a key driving factor; however, published studies have not been systematically reviewed. This systematic review and meta-analysis aimed to determine whether the RMR of people with SMI assessed by indirect calorimetry differs from (i) controls, (ii) predictive equations and (iii) after administration of antipsychotic medications. Five databases were searched from database inception to March 2022. Thirteen studies providing nineteen relevant datasets were included. Study quality was mixed (62 % considered low quality). In the primary analysis, RMR in people with SMI did not differ from matched controls (n 2, standardised mean difference (SMD) = 0·58, 95 % CI -1·01, 2·16, P = 0·48, I2 = 92 %). Most predictive equations overestimated RMR. The Mifflin-St. Jeor equation appeared to be most accurate (n 5, SMD = -0·29, 95 % CI -0·73, 0·14, P = 0·19, I2 = 85 %). There were no significant changes in RMR after antipsychotic administration (n 4, SMD = 0·17, 95 % CI -0·21, 0·55, P = 0·38, I2 = 0 %). There is little evidence to suggest there is a difference in RMR between people with SMI and people without when matched for age, sex, BMI and body mass, or that commencement of antipsychotic medication alters RMR.

Indirect Calorimetry to Measure Metabolic Rate and Energy Expenditure in Psychiatric Populations: A Systematic Review

Psychiatric and metabolic disorders are highly comorbid and the relationship between these disorders is bidirectional. The mechanisms underlying the association between psychiatric and metabolic disorders are presently unclear, which warrants investigation into the dynamics of the interplay between metabolism, substrate utilization, and energy expenditure in psychiatric populations, and how these constructs compare to those in healthy controls. Indirect calorimetry (IC) methods are a reliable, minimally invasive means for assessing metabolic rate and substrate utilization in humans. This review synthesizes the extant literature on the use of IC on resting metabolism in psychiatric populations to investigate the interaction between psychiatric and metabolic functioning. Consistently, resting energy expenditures and/or substrate utilization values were significantly different between psychiatric and healthy populations in the studies contained in this review. Furthermore, resting energy expenditure values were systematically overestimated when derived from predictive equations, compared to when measured by IC, in psychiatric populations. High heterogeneity between study populations (e.g., differing diagnoses and drug regimens) and methodologies (e.g., differing posture, time of day, and fasting status at measurement) impeded the synthesis of results. Standardized IC protocols would benefit this line of research by enabling meta-analyses, revealing trends within and between different psychiatric disorders.

Weight gain and obesity in schizophrenia: epidemiology, pathobiology, and management

OBJECTIVE

To review recent advances in the epidemiology, pathobiology, and management of weight gain and obesity in patients with schizophrenia and to evaluate the extent to which they should influence guidelines for clinical practice.

METHOD

A Medline literature search was performed to identify clinical and experimental studies published in 2005-2014 decade.

RESULTS

Weight gain and obesity increase the risk of adult-onset diabetes mellitus and cardiovascular disorders, non-adherence with pharmacological interventions, quality of life, and psychiatric readmissions. The etiology includes adverse effects of antipsychotics, pretreatment/premorbid genetic vulnerabilities, psychosocial and socioeconomic risk factors, and unhealthy lifestyle. Patients with schizophrenia have higher intake of calories in the form of high-density food and lower energy expenditure. The inverse relationship between baseline body mass index and antipsychotic-induced weight gain is probably due to previous antipsychotic exposure. In experimental models, the second-generation antipsychotic olanzapine increased the orexigenic stimulation of hypothalamic structures responsible for energy homeostasis.

CONCLUSION

The management of weight gain and obesity in patients with schizophrenia centers on behavioural interventions using caloric intake reduction, dietary restructuring, and moderate-intensity physical activity. The decision to switch antipsychotics to lower-liability medications should be individualized, and metformin may be considered for adjunctive therapy, given its favorable risk-benefit profile.

Evaluation of physical fitness parameters in patients with schizophrenia

The aims of this study were to compare aerobic and anaerobic exercise capacities, pulmonary functions, body composition and fat distribution parameters in patients with schizophrenia and healthy controls and to investigate the associations among these parameters. Sixty (30 male, 30 female) patients with schizophrenia and 60 (30 male, 30 female) healthy controls were included in the study. Maximal aerobic capacity was estimated with the Astrand submaximal exercise protocol, and anaerobic performance was determined with a Wingate test. Body composition was established with a bioelectrical impedance analyzer. Pulmonary function tests, skinfold thickness and body circumference measurements were also carried out. Maximal aerobic capacity, maximal anaerobic power, anaerobic capacity and pulmonary function tests (forced vital capacity and maximal voluntary ventilation) were found to be lower in male and female schizophrenic groups as compared to the controls. Body fat percentage, waist and abdomen circumferences, and waist to hip ratio were found to be higher in female schizophrenic patients than in controls. We suggest that maximal aerobic capacity, maximal anaerobic power, and anaerobic capacity are poor in the schizophrenia patients as compared to healthy controls. Low cardiorespiratory fitness is related to reduced pulmonary function and impaired body composition in schizophrenia patients.

C-reactive protein is elevated in schizophrenia

BACKGROUND

Increased levels of inflammatory markers have been reported in schizophrenia, but few studies have examined levels of high sensitivity C-reactive protein (CRP), a non-specific inflammatory marker.

METHODS

Levels of high sensitivity CRP were measured in individuals with schizophrenia, bipolar disorder, and non-psychiatric controls. Linear regression analyses were used to compare the CRP levels among the three groups adjusting for demographic and clinical variables. Logistic regression analyses were used to determine the odds ratios associated with elevated levels of CRP, defined as >=75th and 90th percentile in the controls.

RESULTS

The sample consisted of 715 individuals: 295 with schizophrenia, 192 with bipolar disorder, and 228 without a psychiatric disorder. The levels of CRP in the schizophrenia group, but not in the bipolar disorder group, were significantly increased compared to controls adjusting for age, gender, race, maternal education, smoking status, and Body Mass Index (BMI) (t=3.78, p=<.001). The individuals with schizophrenia had significantly increased odds of having elevated levels of CRP relative to both the 75th and 90th percentile levels of the controls adjusting for the same covariates (OR 1.79, 95% CI 1.14, 2.82; p=.012; OR 2.76, 95% CI 1.58, 4.83, p=<.001). In the multivariate linear and logistic regression analyses, levels of CRP were also associated with BMI and female gender.

CONCLUSIONS

Individuals with schizophrenia may be at risk for the adverse health consequences associated with elevated CRP in the overall population. Trials of interventions directed at lowering the level of CRP and other inflammatory markers are indicated.

Physical capacity, respiratory quotient and energy expenditure during exercise in male patients with schizophrenia compared with healthy controls

BACKGROUND

Despite massive research on weight gain and metabolic complications in schizophrenia there are few studies on energy expenditure and no current data on physical capacity.

AIM

To determine oxygen uptake capacity, respiratory quotient (RQ) and energy expenditure during a submaximal exercise test in patients with schizophrenia and healthy controls.

METHOD

Ten male patients and 10 controls were included. RQ and energy expenditure were investigated with indirect calorimetry during a cycle ergometer test. The submaximal work level was defined by heart rate and perceived exhaustion. Physical capacity was determined from predicted maximal oxygen uptake capacity (VO(2-max)).

RESULTS

The patients exhibited significantly higher RQ on submaximal workloads and lower physical capacity. A significant lower calculated VO(2-max) remained after correction for body weight and fat free mass (FFM). Energy expenditure did not differ on fixed workloads.

CONCLUSION

RQ was rapidly increasing in the patients during exercise indicating a faster transition to carbohydrate oxidation and anaerobic metabolism that also implies a performance closer to maximal oxygen uptake even at submaximal loads. This may restrict the capacity for everyday activity and exercise and thus contribute to the risk for weight gain. Physical capacity was consequently significantly lower in the patients.