Obesity and Negative Affect: A Multi-Disciplinary Exploration of the Interaction Between Mental and Physical Health and its Effect on Cognitive Function

Abstract

Background

In 2015 The ROAMER project used expert consultation to set priorities for public mental health. These included increased research into the interaction between mental and physical health conditions. This thesis examines the interactions between obesity and affective disorders, two major foci for public health, using a range of investigative methods. The research was used to develop a neurocognitive model to explain mental-physical health links between the conditions.

Methods

Study 1 BMI and loneliness: analysed longitudinal research data from a large high-quality multidisciplinary health study (the Quebec Longitudinal Study of Child Development; n=1042: female = 572) utilising anthropometry and loneliness measures to examine the interaction between adiposity and socially mediated negative affect over time. Confirmation of the longitudinal relationship between these variables was used to develop a novel theoretical model to explain the neurocognitive mechanisms that link and reinforce these conditions.

Study 2 Body mass, negative affect, and cognitive function: A multi-disciplinary investigation of anthropometric, affective, and neurocognitive indicators in a single sample of young adults (n=90). Measures of BMI, waist circumference (WC), depression, anxiety, rumination and worry, cognitive performance (Continuous Performance Task of attention, Simon task of spatial response inhibition), and self-reported executive function problems (BRIEF scale). Neurovascular activity (functional near infra-red spectroscopy) and functional connectivity were examined by health group during resting state and task.

Results

Study 1: A series of hierarchical regressions found a significant linear effect of BMI on loneliness (Beta = 0.11) and a significant curvilinear effect of loneliness on BMI (Beta = 0.02) one year later. These reciprocal effects are likely to be mutually reinforcing over time. The study shed light on the time-course of physical and mental health effects between negative affect and body mass.

Study 2: Negative Affect and Adiposity: brooding rumination predicted BMI and WC; WC predicted rumination (explaining around 5% variance). Cognitive performance: The high BMI group (>30) displayed more attention and inhibition errors than low BMI. The high depression and brooding rumination groups displayed more response inhibition errors. Self-Reported Executive Function Problems. The high self-reported inhibition group had more attention errors, and the inhibition error rate was approaching significance. BRIEF subscales were strongly and positively associated with negative affect, and moderately associated with BMI (r=.30) and WC (r=.32). Neurovascular activity in the frontal and temporal lobe. In the resting state higher WC was related to reduced left frontal neurovascular activity (6% variance explained). Higher worry was related to more activity in the right temporal region (explaining 8% of variance). Those high in brooding rumination had greater functional connectivity in the temporal lobe and frontal gyrus than low brooders (superior and medial) during the resting state, but the reverse pattern was observed during the cognitive tasks (functional connectivity was much less extensive). The high WC risk group had reduced functional connectivity in the resting state and attention task, but widespread functional connectivity during the inhibition task.

Conclusion

Study 1 makes important contributions to our understanding the temporal relationship between adiposity and negative affect. Study 2 identifies repetitive negative thinking as an important predictor of health and cognition and a potential target for intervention to address the negative reinforcement between weight gain and negative affective conditions. Evidence also supports the proposed theoretical model which to my knowledge is the first to attempt to explain the neurocognitive processes that mediate physical and mental health through repetitive negative cognition.