Technologies for global health Howitt, Peter, MA; Darzi, Ara, Prof; Yang, Guang-Zhong, Prof ...
The Lancet (British edition),
08/2012, Volume:
380, Issue:
9840
Journal Article
Peer reviewed
Mechanical ventilation and intravenous sedation were initiated. Because of continuing spasms, intrathecal baclofen (1200 µg per day) was started on day 3 with a good clinical response. No ...recommendations about tetanus prophylaxis procedures for wound man agement in patients with blood diseases are available, except for bone-marrow transplantation.
There is evidence that executive function, and specifically inhibitory control, is related to obesity and eating behavior. The goal of this study was to determine whether personality traits and ...inhibitory control predict weight loss after bariatric procedures. Although the impressive weight reduction after bariatric surgery has been shown in short- and medium-term studies, the effect of personality traits on this reduction is uncertain. Specifically, the effect of impulsivity is still largely unknown.
Patients attending either a multidisciplinary information session or outpatient clinic at the Imperial Weight Management Centre were recruited with informed consent into the trial over a 4-month period from January to April 2013. Participants were invited to attend behavioral testing on an outpatient basis in a silent room invigilated by a single researcher.
Forty-five bariatric patients participated in the study (25 patients had a gastric bypass, with a mean BMI of 41.8 and age of 39.0 years; 20 had a sleeve gastrectomy, with a mean BMI of 47.2 and age of 49.0 years). All patients completed personality measures of impulsivity-Barratt's Impulsivity Scale, as well as behavioral measures of impulsivity-the stop-signal reaction-time (SSRT) task measuring inhibitory control and the temporal discounting task measuring reward processing. Those measures were examined in relation to weight loss 6 months after surgery.
The surgical procedure and changes in the behavioral measure of inhibitory control (SSRT) were found to be significant predictors of reduction in body mass index (BMI) in patients undergoing bariatric surgery. The sleeve gastrectomy group found a reduction in BMI of 14.1%, which was significantly less than the 25% reduction in BMI in the gastric bypass group. The direction (parameter estimate) of the significant effect was positive for SSRT change, which indicates that pre- and postreduction in impulsivity predicts reduction in BMI.
Impulsivity measures predict weight reduction in patients undergoing bariatric surgery. This result has implications for predicting outcomes from surgical treatments of obesity.
Abstract Background Obesity is a complex multifactorial condition for which the treatment needs to be tailored to the individual patient. Cognitive behavioural therapy (CBT) is the mainstay for most ...obesity treatments. Obesity has been compared with addictive behaviours in which people show characteristics of dysfunctional impulsivity, which manifest as deficits in inhibitory control. We aimed to examine the effect of CBT on the objective behavioural manifestations of impulsivity during weight loss in obese adolescents. Methods 31 obese adolescents (21 boys, 17 girls) with a mean age of 14·0 years (SD 0·3) and a body-mass index (BMI) of 33·6 kg/m2 (0·9) attending an obesity camp were tested for impulsivity with the CANTAB (Cambridge, UK; Cambridge Cognition) Stop Signal Task. Tasks were undertaken before the CBT intervention, 6 weeks after the intervention (range 3–8 weeks), and at 6 month follow-up. The inclusion criteria were being obese when adjusted for age and sex, having had regular education up to GCSE level (at age 15–16 years), and being aged between 11 and 17 years. We excluded patients with a formal diagnosis of attention deficit hyperactivity disorder or an eating disorder, those receiving antipsychotic drugs, and those with a serious physical disability restricting physical activity. Findings Mean BMI fell from 33·60 kg/m2 (SD 5·0; n=31) before camp to 30·94 kg/m2 (4·5; n=31) at the end of camp (p=0·01). At 6 month follow-up, participants' weight loss had plateaued, with a mean BMI of 31·27 kg/m2 (SD 5·0; n=12, p=0·04). Reduction in impulsivity after the intervention remained when age and length of stay in camp were controlled for with a general linear model (23·9 ms 86·45; p=0·03). Impulsivity measurements were available in 26 of 31 adolescents at the end of camp. Reasons for loss to follow-up were being unwell (n=1) on the day of data collection and leaving camp for the day (n=4). Loss to follow-up was accounted for in the statistical analysis by use of a complete case analysis of all available covariates. Correlations showed a positive relation between length of stay in camp and reduction in stop signal reaction time (SSRT; r2 =0·20, p=0·03), whereas we noted an inverse relation between age and reduction in SSRT (F=7·723, p=0·011). At 6 months, 12 of 31 adolescents were followed up. In these patients, impulsivity scores decreased by a mean of 108·45 ms (SD 95·7; p=0·008) compared with baseline values. At 6 months, general linear regression did not show any significant associations; however, impulsivity scores were weakly associated with a reduction in BMI (r2 =0·139; p=0·061). Interpretation Impulsivity is an automatic behaviour pattern, thought to be stable over time. We showed that the stop signal task—a commonly used method to measure impulsivity—can be modified over time. Existing data suggest that impulsive individuals are more likely to be obese, but our data suggest that impulsivity might also be associated with weight loss and its maintenance. Limitations of the study include the before and after design in which participants could become familiar with the SSRT task, which could account for the improved scores after camp. We did not measure the intellectual ability of participants, which could be a confounding factor. The follow-up environments were also uncontrolled. This study further contributes to research of obesity based on an addictive behaviour model and treatment implications. Funding None.
Abstract Background Childhood obesity tracks into adulthood, meaning obesogenic behaviours learned in early years are likely to be sustained throughout life. Studies of the neurocognitive mechanisms ...underlying obesity-related behaviours have implicated the role of impulsivity in weight gain. Food-related and physical-activity-related impulsive actions such as discounting of the future health benefits of present rewards or the inability to inhibit tempting unhealthy choices can lead to gradual weight gain. Impulsivity was compared in a group of obese and non-obese adolescents to test this hypothesis. Methods 47 obese adolescents (mean body-mass index BMI 33·22 SD 8·0) who attended a residential lifestyle summer camp with a mean age of 14·28 years (SD 1·7) were recruited with parental consent over two summers. A normal weight control group (BMI 20·6 SD 2·3) with a mean age of 13·83 years (SD 1·7) from a UK secondary school were used for comparison. Behavioural measures of impulsivity were tested using the stop signal reaction time (SSRT) as a marker of inhibitory control and the temporal discounting constant for monetary rewards. Self-reported scores of impulsivity using Cloninger's junior temperament and character inventory were correlated with behavioural measures by use of a Spearman's correlation. Findings The non-obese group had better inhibitory control as measured by the SSRT with a mean value of 156·93 ms (SD 43·12) compared with the obese group with a mean value of 218·42 ms (80·48; p=0·0001). Additionally, SSRT direction errors were significantly higher in the obese adolescents (5·48 SD 4·88) than in normal weight individuals (2·88 0·41; p=0·0001), and the proportion of successful stops were significantly higher in the normal weight adolescents (0·49 SD 0·1) than in the obese group (0·53 0·09; p=0·02). Those who were obese (k=0·56 SD 0·36) were found to discount the future value of money significantly more than normal weight individuals (0·40 0·29; p=0·018) and scored higher on the novelty seeking subscale of the junior temperament and character inventory (r=0·23; p=0·03). Interpretation Impulsivity is a unitary construct, which is an independent predictor of BMI in adults and may act as a causal factor in adolescents. Obese adolescents exhibit poor inhibitory control and discount the future for monetary rewards more than their non-obese counterparts. In addition, there were greater response errors and a failure to stop during the no-go paradigm, suggesting the presence of either inattention or hyperactive traits in addition to impulsive behaviours in the obese group. The difference in socioeconomic status between both groups may be a confounding factor and was not available for analysis. Bias was reduced by ensuring all participants were in full-time education, matched for age, and masked to testing. Understanding of the neurocognitive mechanisms underlining obesogenic behaviours such as impulsivity is needed to improve existing interventions, through the development of novel methods to train self-control and self-efficacy as part of a personalised approach to weight reduction. Funding None.
