RT Journal Article SR Electronic T1 Neural bases of the clinical and neurocognitive differences between early- and late-onset obsessive–compulsive disorder JF Journal of Psychiatry and Neuroscience JO J Psychiatry Neurosci FD Canadian Medical Association SP 234 OP 242 DO 10.1503/jpn.190028 VO 45 IS 4 A1 Taekwan Kim A1 Seoyeon Kwak A1 Ji-Won Hur A1 Junhee Lee A1 Won-Gyo Shin A1 Tae Young Lee A1 Minah Kim A1 Jun Soo Kwon YR 2020 UL http://jpn.ca/content/45/4/234.abstract AB Background: Using biological evidence to define subtypes within the heterogeneous population with obsessive–compulsive disorder (OCD) is important for improving treatment response. Based on age at onset, OCD can be clustered into 2 groups, each of which is more homogeneous with respect to clinical and cognitive phenotype. However, the neural bases for these phenotypic differences need to be established to construct evidence-based homogeneous groups.Methods: We compared brain volumes, clinical symptoms, and neurocognitive function for 49 people with early-onset OCD and 52 with late-onset OCD (participants in both groups were unmedicated or drug-naïve), and 103 healthy controls. We performed regression analyses to examine group × volume interaction effects on clinical outcomes or neurocognitive function in people with OCD.Results: We observed larger volumes in the precentral, orbitofrontal, middle frontal, and middle temporal gyri in people with early-onset OCD compared to those with late-onset OCD. Poorer visuospatial construction in early-onset OCD was correlated with a larger left middle frontal gyrus volume. Impaired visuospatial memory in people with early-onset OCD and cognitive inflexibility in people with late-onset OCD were correlated with increased and decreased volume in the left middle frontal gyrus, respectively. We found group × volume interactions for obsessive–compulsive symptom scores in the left middle temporal gyrus of people with OCD.Limitations Although we divided the subtypes using the commonly adopted criterion of age at onset, this criterion is still somewhat controversial.Conclusion: We provided the neural bases for clinical and neurocognitive differences to demonstrate that biological evidence underlies the distinctions between early- and late-onset OCD. This study suggests that different treatment options should be considered for the OCD subtypes, because their neurobiology differs and is related to distinct phenotypic profiles.