By combining a psychological assessment tool with a non-invasive optical neuroimaging technique, researchers were able to obtain a comprehensive study of the neural mechanisms involved in food addiction. This approach yielded valuable insights into potential therapeutic strategies for food addiction.
Food addiction is characterised as a chronic condition linked to impaired cognitive control circuits triggered by emotional and environmental conditions.
It is said that individuals who suffer from food addiction often have impaired executive functions that include working memory, cognitive flexibility, and inhibition control, which may also impede the effectiveness of food addiction treatments. There has been increasing research showing that the prefrontal cortex plays a crucial role in the cognitive process of behavioural addiction. Moreover, disrupted functions in the prefrontal cortex can lead to reduced motivation for healthy habits and exacerbate dysfunctional behaviours such as weight gain.
However, there is a lack of optical neuroimaging studies investigating functional and cognitive impairments. Additionally, the specific cognitive resources that become constrained in the absence of self-control and regulation skills in food addiction remain unclear.
In a study published in the Journal of Innovative Optical Health Sciences, researchers from the University of Macau used functional near-infrared spectroscopy (fNIRS), a robust optical neuroimaging technique, to detect hemodynamic responses in the prefrontal cortex. The researchers utilised the fNIRS optical neuroimaging technique to investigate the neural substrates associated with impaired executive functions in food addiction and examine the relationship between self-control and regulation and food addiction.
Additionally, the Yale Food Addiction Scale (YFAS), which was developed to explore the association of cognitive impairments with food addiction, was also used in this study. YFAS assesses seven food addiction symptoms and clinically significant impairments. Thus, higher YFAS scores correlate with increased impulsivity, more frequent episodes of binge eating, and heightened cravings.
The researchers applied a reliable non-invasive methodological solution (i.e., the fNIRS) combined with a validated clinical inventory (i.e., the YFAS) method to provide a methodological, theoretical, and therapeutical study of food addiction, in order to investigate both the executive and affective behaviour neural mechanisms that are involved in food addiction.
For the study, participants had to perform three different tasks to evaluate executive functions of working memory, cognitive flexibility, and inhibition control. For each task, participants were presented with a picture of junk or healthy food, and the average changes in oxyhemoglobin and deoxyhemoglobin were obtained from 14 different parts of the cortex of the participants.
Among the participants in this study, 12 met the YFAS criteria for the food addiction group and 11 met the criteria for the healthy eating group.
Results from the three different tasks confirmed with previous studies that impaired executive functions exist in the prefrontal cortex of food-addicted individuals.
First, the results indicated that impaired working memory in the food addiction group was associated with the consumption of highly appetising food, frequent binge-eating episodes, increased depression, increased cravings, and reduced weight loss. When the working memory function becomes overloaded with enticing food images, it becomes more challenging for the participant to maintain self-control and make decisions that prioritise long-term benefits. Thus, more vascular resources are required in order to process enticing food images and maintain proper working memory function. This, in turn, reflects a decrease in cognitive control and slower behavioural responses, such as a lack of self-control, inability to regulate cravings, and strong negative emotions.
Results from the cognitive flexibility task revealed that the shifting mechanism in the prefrontal cortex is when coping with highly appetising food, compared with neutral and healthy food. Consistent with previous studies, this finding showed that impaired cognitive flexibility is associated with obsessive-compulsive disorder and food addiction behaviours.
Finally, the results showed that inhibition control is associated with higher brain activation in the junk conditions, compared to healthy conditions. This is because, in junk conditions, higher brain activity was in response to recruiting more vascular resources and higher-order cognitive skills such as planning, decision-making, and attentional control.
The fNIRS serves as a valuable non-invasive and patient-friendly tool for the detection of food addiction disorders, providing accurate insights into the understanding of food addiction and possible new treatment strategies. Further, the combined fNIRS-YFAS method provides a novel approach to gaining insights into food addiction therapeutic strategies, whereby the specific role of working memory associated with self-control and regulation mechanisms is crucial for the treatment of food addiction. [APBN]
Source: Couto, T. A., Wang, M. Y., & Yuan, Z. (2022). Optical neuroimaging of executive function impairments in food addiction. Journal of Innovative Optical Health Sciences, 15(01), 2250005. https://doi.org/10.1142/S1793545822500055