Neurocognitive measures of impulsivity: explanatory, diagnostic and a prognostic role in obesity
File(s)
Author(s)
Kulendran, Myutan
Type
Thesis
Abstract
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.
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.
Version
Open Access
Date Issued
2014-05
Date Awarded
2014-08
Copyright Statement
Attribution NoDerivatives 4.0 International Licence (CC BY-ND)
Advisor
Darzi, Ara
Publisher Department
Department of Surgery & Cancer
Publisher Institution
Imperial College London
Qualification Level
Doctoral
Qualification Name
Doctor of Philosophy (PhD)