The disinhibited binge eating style often seen in individuals with high ADHD symptoms is attributable to a heightened neural reward response to food rather than to the impulsivity that’s a core feature of ADHD, Elizabeth Martin, MSc, reported at the virtual congress of the European College of Neuropsychopharmacology.
She presented a functional MRI brain-imaging study designed to help pin down the mechanism involved in the disordered eating patterns that often accompany ADHD.
“Determining the underlying mechanism between binge eating and ADHD may be helpful in developing novel therapies for both ADHD and binge eating disorder. Our research suggests that further investigation of the role of altered reward processing in ADHD may be an avenue for this,” said Ms. Martin, a doctoral researcher in the department of psychology at the University of Birmingham (England).
She and her coinvestigators recruited 31 university student volunteers with high ADHD symptoms as evidenced by their mean score of 29.3 on the 0-54 Conners’ Adult ADHD Rating Scale, and 27 others with low ADHD symptoms and a mean Conners’ score of 6.8. The two groups didn’t differ in age or BMI. However, not surprisingly, the high-ADHD group exhibited greater impulsivity, with a mean score of 72 on the Barratt Impulsiveness Scale, versus 56.5 in the low ADHD group.
A battery of eating disorder scales was applied to assess participants in terms of binge/disinhibited or restrictive eating patterns. The high- and low–ADHD symptom groups didn’t differ in terms of prevalence of a restrictive eating style, which was low, but the high-ADHD participants scored on average roughly 50% higher on the binge/disinhibited eating style measure, compared with the low-ADHD group.
Each study participant underwent a 1-hour BOLD (blood oxygen level dependent) functional MRI scan while performing two sets of tasks. One task entailed quickly looking at 120 photos of food items and an equal number of nonfood items and rating how appealing the pictures were. The other challenge was what psychologists call a go/no-go task, a computerized cognitive test used to assess inhibitory control based upon reaction times and error rates.
On the go/no-go task, there were no between-group differences in rates of errors of omission or commission or reaction time. Moreover, the MRI results indicated there were no between-group differences in neural circuitry activation during this task. The investigators therefore concluded that the tendency toward binge eating in the high–ADHD symptoms group was not tied to greater impulsivity as reflected in less effective inhibitory processes.
The food picture rating task told a different story. The MRIs demonstrated increased responses to food versus nonfood images in the high-ADHD subjects, compared with the low-ADHD subjects in reward-related brain areas, including the ventromedial prefrontal cortex, caudate nucleus, and ventral tegmental area.
in response to viewing food pictures,” according to Ms. Martin. “This suggests that enhanced responsiveness to food cues may be a mediating mechanism underlying overeating in ADHD.”
Of note, only one drug – lisdexamfetamine dimesylate (Vyvanse) is Food and Drug Administration-approved for the treatment of both ADHD and binge-eating disorder.
“Until now it’s been unclear how lisdexamfetamine dimesylate reduces binge eating, but our results suggest that one mechanism worthy of further investigation is the potential effect of the drug on food reward processes,” Ms. Martin said.
She reported having no financial conflicts regarding the study, which was supported by university funding.
SOURCE: Martin E. ECNP 2020. Abstr. P.041.