[11C]Martinostat uptake in AD correlated with regional class I HDAC changes postmortem, corresponding with regionally elevated beta-amyloid and tau, and correlated with cortical atrophy and cognitive impairment.(40) As AD co-pathologies of beta-amyloid and tau are common in both DLB and PD dementia,(31–33) comorbid AD pathologic changes may contribute to the decreased [11C]Martinostat uptake in parietal and temporal regions observed here in DLB and in cognitively impaired PD participants. The gene discussed is HDAC9; the disease is Parkinson disease.