Inverse Association of Circulating SIRT1 and Adiposity: A Study on Underweight, Normal Weight, and Obese Patients.

Context: Sirtuins (SIRTs) are NAD+-dependent deacetylases, cellular sensors to detect energy availability, and modulate metabolic processes. SIRT1, the most studied family member, influences a number of tissues including adipose tissue. Expression and activity of SIRT1 reduce with weight gain and increase in conditions of starvation. Objective: To focus on SIRT1 plasma concentrations in different conditions of adiposity and to correlate SIRT1 with fat content and distribution, energy homeostasis and inflammation in under-weight, normal-weight, and obese individuals. Materials and Methods: 21 patients with anorexia nervosa, 26 normal-weight and 75 patients with obesity were evaluated. Body fat composition by dual-energy X-ray absorptiometry, ultrasound liver adiposity, echocardiographic epicardial fat thickness (EFT), inflammatory (ESR, CRP, and fibrinogen), and metabolic (FPG, insulin, LDL- and HDL-cholesterol, triglycerides) parameters, calculated basal metabolic rate (BMR) and plasma SIRT1 (ELISA) were measured. Results: SIRT1 was significantly higher in anorexic patients compared to normal-weight and obese patients (3.27 ± 2.98, 2.27 ± 1.13, and 1.36 ± 1.31 ng/ml, respectively). Linear regression models for each predictor variable adjusted for age and sex showed that SIRT1 concentration was inversely and significantly correlated with EFT, fat mass %, liver fat content, BMR, weight, BMI, WC, LDL-cholesterol, insulin, ESR. Stepwise multiple regression analysis revealed that age and EFT were the best independent correlates of SIRT1 (ß = -0.026 ± 0.011, p = 0.025, and ß = -0.516 ± 0.083, p < 0.001, respectively). Conclusions: Plasma SIRT1 shows a continuous pattern that inversely follows the whole spectrum of adiposity. SIRT1 significantly associates with EFT, a strong index of visceral fat phenotype, better than other indexes of adiposity studied here.

Obesity is associated with lack of inhibitory control and impaired heart rate variability reactivity and recovery in response to food stimuli.

Recent theories compare obesity with addiction in terms of lack of inhibitory control in both clinical populations. The present study hypothesized impaired inhibition in obese patients reflected both in executive functions and reduced vagal tone (indexed by a decrease in heart rate variability; HRV) in response to food stimuli. Twenty-four inpatients with obesity (19 women) and 37 controls (24 women) underwent ECG monitoring during baseline, food stimuli viewing, and a recovery phase. Tests and questionnaires assessing inhibitory control and psychopathological dispositions were also administered. As hypothesized, patients were characterized by deficits in all the tests measuring inhibitory capacities. Results also show greater HRV reduction and impaired HRV recovery in response to food stimuli in obese patients compared to controls. The drive to eat experienced by obese patients in the absence of caloric need may rely on impairments in inhibitory and vagal functioning. Results are discussed in terms of implications for therapy.

No differential effect of age on brain matter volume and cognition in bipolar patients and healthy individuals.

BACKGROUND: Bipolar disorder (BD) is associated with brain structural and cognitive abnormalities. There is a paucity of evidence regarding the evolution of these deficits over time. This study examined the relationship between age and brain morphology and cognition in patients with BD type I. METHODS: Brain structural magnetic resonance imaging data were acquired using a 1.5T scanner from 71 BD patients and 82 age- and gender-matched controls and analysed using Statistical Parametric Mapping. In addition, participants were evaluated using the Wechsler Adult Intelligence Scale, Revised; the Wechsler Memory Scale, third edition; the Hayling Sentence Completion Task, a measure of response inhibition; and the Wisconsin Card Sorting Test, which reflects rule discovery and perseveration. RESULTS: We found a significant effect of age but not of diagnosis and no age-by-diagnosis interaction in global gray and white matter and cerebrospinal fluid volumes. There was no differential effect of age on the two diagnostic groups with respect to cognitive task performance. CONCLUSIONS: Our findings do not support differential age-related changes in brain structure and cognition in patients with bipolar disorder compared to healthy individuals. Cross-sectional studies are, however, limited and longitudinal data will be required to further explore this issue.