Cerebral blood flow in attention deficit hyperactivity disorder: A systematic review.

Background and Objectives: Attention deficit hyperactivity disorder (ADHD) is one of the most frequent and disabling neurodevelopmental disorders. Recent research on cerebral blood flow (CBF) has enhanced understanding of the underlying pathophysiology in neuropsychiatric disorders. This systematic review aims to synthesize the existing literature on CBF anomalies among individuals with ADHD in comparison to controls.
Methods: Following the PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) approach, a systematic literature search was conducted using PubMed, PsycInfo, and Web of Science to identify relevant studies on CBF in ADHD.
Results: Twenty studies, encompassing a total of 1652 participants with ADHD and 580 controls, were included, employing measurements from SPECT (n = 9), ASL (n = 6), PET (n = 4), and BOLD-derived quantitative maps (n = 1). In individuals with ADHD during resting state, hypoperfusion was frequently observed in the right orbitofrontal gyrus, temporal cortex, basal ganglia and putamen. Conversely, hyperperfusion was noted in frontal lobes, left postcentral gyrus, and occipital lobes. During cognitive tasks, hyperperfusion was observed in frontal areas, temporal regions, cingulate cortex and the precuneus. Furthermore, the administration of methylphenidate was associated with increased CBF in striatal and posterior periventricular regions, the right thalamus, and the precentral gyrus.
Conclusion: This review highlights diverse CBF anomalies in ADHD. The most consistently reported findings suggest hypoperfusion during resting state in prefrontal and temporal areas, along with the basal ganglia, while there is a hyperperfusion in frontal, parietal and occipital regions. Further research, including longitudinal studies, is essential to develop a comprehensive understanding of CBF implications in ADHD.
Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.
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