Lisdexamfetamine Alters BOLD-fMRI Activations Induced by Odor Cues in Impulsive Children

Abstract

Introduction: Lisdexamfetamine (LDX) is a drug used to treat ADHD/impulsive patients. Impulsivity is known to affect inhibitory, emotional and cognitive function. On the other hand, smell and odor processing are known to be affected by neurological disorders, as they are modulators of addictive and impulsive behaviors specifically. We hypothesize that, after LDX ingestion, inhibitory pathways of the brain would change, and complementary behavioral regulation mechanisms would appear to regulate decision-making and impulsivity. Methods: 20 children were studied in an aleatory crossover study. Imaging of BOLD-fMRI activity, elicited by olfactory stimulation in impulsive children, was performed after either LDX or placebo ingestion. Results: Findings showed that all subjects that underwent odor stimulation presented activations of similar intensities in the olfactory centers of the brain. This contrasted with inhibitory regions of the brain such as the cingulate cortex and frontal lobe regions, which demonstrated changed activity patterns and intensities. While some differences between the placebo and medicated states were found in motor areas, precuneus, cuneus, calcarine, supramarginal, cerebellum and posterior cingulate cortex, the main changes were found in frontal, temporal and parietal cortices. When comparing olfactory cues separately, pleasant food smells like chocolate seemed not to present large differences between the medicated and placebo scenarios, when compared to non-food-related smells. Conclusions: We demonstrated that LDX, first, altered the inhibitory pathways of the brain, second, increased activity in large amounts of brain regions which were not activated by smell in drug-naïve patients, third, facilitated a complementary behavioral regulation mechanism, run by the cerebellum, which regulated decision-making and impulsivity in motor and frontal structures.

BOLD Activation During the Application of MOXO-CPT in School Patients With and Without Attention Deficit Hyperactivity Disorder

“…It is therefore an ideal instrument to study the response of ADHD patients to different stimuli. BOLD and fMRI have been used to study ADHD in the past and there are many publications in the field ( de Celis et al, 2019 ; De Silva et al, 2019 ; Guerrero et al, 2016 ; Tobón et al, 2020 ; Rubia et al, 2021 ). However, works that combines the use of MOXO with BOLD imaging studies with fMRI are, to our knowledge, scarce or non-existent.…”