With regard to retrospectively ascertained age at onset in adult patients, the lack of inferior parietal abnormalities in the adult sample with childhood onset might be explained by insufficient power. When looking at the effect sizes, decreased cortical thickness of the inferior parietal cortex was present in adult patients with a childhood disease onset compared to healthy controls, but at a less stringent significance threshold. The effect size was even slightly larger than the effect size of the main group comparison suggesting a power issue, rather than a lack of inferior parietal abnormalities. In contrast, adult illness onset was associated with widespread thinner cortices. The adult-onset group is older than the childhood-onset group, but also has a higher percentage of medicated patients. Post hoc analyses showed that these effects mostly disappear when correcting for medication status suggesting that these findings are mainly driven by medication.
