Neural correlates of illness awareness in obesity: an exploratory pilot fMRI study

Obesity is a complex condition that negatively impacts health, quality of life, and life expectancy. Nonadherence to existing clinical interventions remains a significant barrier for patients with obesity, with 80% of overweight individuals struggling to maintain long-term weight loss. Impaired illness awareness is a factor that may contribute to treatment nonadherence. Previous functional imaging studies in other conditions have suggested that impaired illness awareness may be related to altered activity or dysconnectivity in frontoparietal regions, including the posterior parietal area (PPA) and dorsolateral prefrontal cortex (dlPFC). As such, this exploratory study aimed to investigate the brain regions associated with impaired illness awareness in individuals with obesity.

A total of 26 participants (Age = 50.4 (14.5), 75% female) with a mean BMI of 37.4 (SD = 5.1) were included. Participants completed an individually tailored subjective obesity awareness task during fMRI. The task paradigm consisted of a bank of brief stimuli, including 'yes/agree' or 'no/disagree' questions/statements derived from the core domains of illness awareness and control stimuli. Obesity awareness was assessed based on response accuracy to the paradigm's obesity-related stimuli. Participants were also grouped into impaired (≤80% response accuracy, n = 14) versus intact obesity awareness (>80%, n = 12). Regression and non-parametric between-group analyses were conducted to assess brain activation, as measured by fMRI blood oxygen level dependent (BOLD) response during the obesity awareness task. Regions of interest for impaired obesity awareness were the PPA, dlPFC, and insula, controlling for age and gender.

Impaired subjective obesity awareness was related to increased BOLD responses in the left PPA, but not the dlPFC and insula during an obesity awareness fMRI task. Similarly, participants with impaired obesity awareness showed increased BOLD response to the obesity awareness task in PPA compared to those with intact obesity awareness.

Impaired obesity awareness may be related to increased brain activation in the PPA, though future replication is needed. Identifying neuroimaging biomarkers of impaired obesity awareness can help provide brain targets for intervention, with a goal of facilitating treatment adherence.