Visceral adipose tissue in patients with severe mental illness

Abdominal Visceral Adipose Tissue and All-Cause Mortality: A Systematic Review

INTRODUCTION

Increased abdominal visceral adipose tissue (VAT) implies an adverse cardio-metabolic profile. We examined the association of abdominal VAT parameters and all-cause mortality risk.

METHODS

We systematically searched four databases. We performed citations/articles screening, data abstraction, and quality assessment in duplicate and independently (CRD42020205021).

RESULTS

We included 12 cohorts, the majority used computed tomography to assess abdominal VAT area. Six cohorts with a mean age ≤ 65 years, examining all-cause mortality risk per increment in VAT area (cm²) or volume (cm³), showed a 11-98% relative risk increase with higher VAT parameters. However, the association lost significance after adjusting for glycemic indices, body mass index, or other fat parameters. In 4 cohorts with a mean age >65 years, the findings on mortality were inconsistent. Conversely, in two cohorts (mean age 73-77 years), a higher VAT density, was inversely proportional to VAT area, and implied a higher mortality risk.

CONCLUSION

A high abdominal VAT area seems to be associated with increased all-cause mortality in individuals ≤ 65 years, possibly mediated by metabolic complications, and not through an independent effect. This relationship is weaker and may reverse in older individuals, most likely secondary to confounding bias and reverse causality. An individual participant data meta-analysis is needed to confirm our findings, and to define an abdominal VAT area cutoff implying increased mortality risk.

SYSTEMATIC REVIEW REGISTRATION

https://www.crd.york.ac.uk/prospero/display_record.php?RecordID=205021, identifier CRD42020205021.

Fat compartments in patients with depression: A meta-analysis

INTRODUCTION

Depressive disorders are a common illness worldwide. Major depression is known as a significant predictor of the metabolic syndrome. However, the effects of depression on adipose tissue compartments are controversial. This meta-analysis aimed to evaluate the state of research on the relationship between patients with depression and adipose tissue compartments as compared to nondepressed individuals.

METHODS

The PubMed database was searched for human studies that measured adipose tissue compartments such as visceral adipose tissue (VAT), subcutaneous adipose tissue (SAT) and/or organ-specific adipose tissue measurements using dual-energy X-ray absorptiometry, magnetic resonance imaging or computed tomography scan and reported the means and a measure of variance separately for depressed individuals and healthy controls. Twelve articles were identified, including a total of 1,141 depressed and 2,545 nondepressed individuals.

RESULTS

Major depressive disorder and self-reported depressive symptoms were associated with elevated visceral adipose tissue and elevated subcutaneous adipose tissue. Subanalyses for gender, age, method of adipose tissue measurement, and method of depression assessment showed elevated visceral adipose in depressed individuals. The results could be replicated when focussing on studies controlling for body mass index (BMI). Regarding other adipose tissue compartments, meta-analysis could not be carried out due to lack of studies.

CONCLUSIONS

Depression is associated with enlarged visceral and subcutaneous adipose tissue. Further, especially longitudinal, research is needed to identify the mechanism through which depressive disorders contribute to visceral adiposity.

Genetic correlations of psychiatric traits with body composition and glycemic traits are sex- and age-dependent

Body composition is often altered in psychiatric disorders. Using genome-wide common genetic variation data, we calculate sex-specific genetic correlations amongst body fat %, fat mass, fat-free mass, physical activity, glycemic traits and 17 psychiatric traits (up to N = 217,568). Two patterns emerge: (1) anorexia nervosa, schizophrenia, obsessive-compulsive disorder, and education years are negatively genetically correlated with body fat % and fat-free mass, whereas (2) attention-deficit/hyperactivity disorder (ADHD), alcohol dependence, insomnia, and heavy smoking are positively correlated. Anorexia nervosa shows a stronger genetic correlation with body fat % in females, whereas education years is more strongly correlated with fat mass in males. Education years and ADHD show genetic overlap with childhood obesity. Mendelian randomization identifies schizophrenia, anorexia nervosa, and higher education as causal for decreased fat mass, with higher body fat % possibly being a causal risk factor for ADHD and heavy smoking. These results suggest new possibilities for targeted preventive strategies.