Neurocognitive measures of impulsivity: explanatory, diagnostic and a prognostic role in obesity

Obesity is a growing public health problem with multiple aetiological factors. Behavioural determinants are likely to be key contributors to obesity, with a need for applied research in this field. Recently the obesity has been compared to food addiction with the connotation that obese individuals are impulsive in their behaviour. Impulsivity is a trait that is closely linked to addiction and has been studied in personality, psychiatry and more recently in the neurocognitive arena. A conceptual review of the construct of impulsivity identified inhibitory control (SST) and temporal discounting (TD) as two key behavioural constructs universal to all the key fields of impulsivity research. A systematic review of the literature supported their use to profile participants based on their Body Mass Index. The validity of the tools were proven by endophenotyping participants (N=202) of both normal weight and those seeking weight loss intervention. Both measures could successfully differentiate between obese and normal weight adolescents (N=85). The SST was also prognostic for short-term weight reduction in adolescents attending a lifestyle intervention, with the TD being able to predict weight loss maintenance at 6 months. The tasks could not differentiate significantly between adults of different weights but the TD was able to predict weight reduction after surgery (N=90). The modifiability of obesity through neuronal dopamine pathways was supported by a randomised controlled trial testing neurocognitive enhancement agents (N=40) against a placebo (N=40) in normal weight adults. Weight was also controlled by a commitment intervention targeting automatic impulsive behaviours (N=27). These findings support an association between impulsivity, obesity and weight reduction. The experimental inferences have been described in terms of a novel interconnected neuronal network, which leaves itself open to testing using functional brain imaging.Open Acces

Does a PBL-based medical curriculum predispose training in specific career paths? A systematic review of the literature

Background North American medical schools have used problem-based learning (PBL) structured medical education for more than 60 years. However, it has only recently been introduced in other medical schools outside of North America. Since its inception, there has been the debate on whether the PBL learning process predisposes students to select certain career paths. Objectives To review available evidence to determine the predisposition of specific career paths when undertaking a PBL-based medical curriculum. The career path trajectory was determined as measured by official Matching Programs, self-reported questionnaires and surveys, and formally defined career development milestones. Methods A systematic literature review was performed. PubMed, Medline, Cochrane and ERIC databases were analysed in addition to reference lists for appropriate inclusion. Results Eleven studies fitting the inclusion criteria were identified. The majority of studies showed that PBL did not predispose a student to a career in a specific speciality (n = 7 out of 11 studies, 64%). However, three studies reported a significantly increased number of PBL graduates working in primary care compared to those from a non-PBL curriculum. Conclusions PBL has been shown not to predispose medical students to a career in General Practice or any other speciality. Furthermore, a greater number of similar studies are required before a definitive conclusion can be made in the future

Diagnostic validity of behavioural and psychometric impulsivity measures : an assessment in adolescent and adult populations

This investigation examined how different psychological and behavioural measures can be used to identify impulsive individuals. Five clinical groups split, between adolescents and adults, with varying levels of weight-management issues, were used to validate the impulsivity measures. The measures consisted of two behavioural, an inhibitory control measure (Stop Signal Task) and a Temporal Discounting measure, along with two personality measures, the Temperament and Character Inventory (Cloninger, Przybeck, Svrakic, & Wetzel, 1994) and the adolescent version (The Junior Temperament and Character Inventory) and finally the Barrat Impulsivity Scale (Patton, Stanford, & Barratt, 1995). The most sensitive was the Stop Signal Reaction time, which depicted significant differences in inhibitory control for all but two groups (Adult Lifestyle and Adult Healthy). The psychometric scales were able to sufficiently discriminate between obese and impulsive individuals with healthier participants. The Self-Control and Novelty Seeking subscales on the BIS. The Novelty Seeking subscale of the TCI-R and the JTCI, significantly discriminated between obese and healthy individuals. There was a high degree of association amongst the measures used, identifying that these measures can be used to monitor and measure impulsiveness in obese individuals for use in weight-loss interventions

Benign tumours of the bone: A review

Benign tumours of the bone are not cancerous and would not metastasise to other regions of the body. However, they can occur in any part of the skeleton, and can still be dangerous as they may grow and compress healthy bone tissue. There are several types of benign tumours that can be classified by the type of matrix that the tumour cells produce; such as bone, cartilage, fibrous tissue, fat or blood vessel. Overall, 8 different types can be distinguished: osteochondroma, osteoma, osteoid osteoma, osteoblastoma, giant cell tumour, aneurysmal bone cyst, fibrous dysplasia and enchondroma. The incidence of benign bone tumours varies depending on the type. However, they most commonly arise in people less than 30 years old, often triggered by the hormones that stimulate normal growth. The most common type is osteochondroma. This review discusses the different types of common benign tumours of the bone based on information accumulated from published literature

Revisional surgery after laparoscopic adjustable gastric banding

During the last decades laparoscopic adjustable gastric banding has been one of the most performed bariatric procedures. The trend has changed since long-term follow ups showed high percentage of complications especially, weight loss failure leading to revisional surgeries. Possible secondary interventions are laparoscopic sleeve gastrectomy (LSG), laparoscopic Roux-en-Y gastric bypass (LRYGB), laparoscopic one anastomosis gastric bypass/ mini-bypass (OAGB) and malabsorptive procedures such as laparoscopic biliopancreatic diversion with duodenal switch. Long term follow-up proved that LSG and LRYGB are equally valid options as revisional surgeries in terms of weight loss and rate of complications. But in recent times the good outcomes of secondary OAGB have aroused the question that whether this is the best choice. The question about which intervention is the best option is still open

Pharmacological manipulation of impulsivity : a randomized controlled trial

Impulsivity is a trait that is closely linked to addiction, which has been studied in personality, psychiatry and more recently in the neurocognitive arena. Recently, even obesity has been compared to food addiction with the connotation that obese individuals are impulsive in their behavior. This research is a conceptual review of the construct of impulsivity identified inhibitory control and temporal discounting as two key behavioral constructs universal to all key fields of impulsivity research. This research aimed to identify the modifiability of impulsivity through neuronal dopamine pathways through the use of two pharmaceutical agents, modafinil and atomoxetine. A randomized controlled trial design was executed to test the aforementioned neurocognitive enhancement agents (n = 20 participants receiving atomoxetine and n = 20 participants receiving modafinil) against a placebo (n = 40) in normal weight adults. The results showed that modafinil but not atomoxetine was effective in reducing deficits in inhibitory control. These findings highlight the multiconstruct nature of impulsivity and the need for psychometric tests, which capture these constructs better

Impulsivity predicts weight loss after obesity surgery

Objective 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. Setting 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. Methods 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. Results 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. Conclusion Impulsivity measures predict weight reduction in patients undergoing bariatric surgery. This result has implications for predicting outcomes from surgical treatments of obesity