This could serve as a further clue regarding the association of the ‘cholinergic deficit’ with different etiologies, as the ITM ratio of glucose metabolism has previously been demonstrated to discriminate between AD and non-AD pathologies.13,21 Hence, patients with predominantly non-AD pathology such as limbic predominant TDP-43, primary age-related tauopathy, or argyrophilic grain disease would be expected to have a smaller ‘cholinergic deficit’ than those with purer AD pathology. Here, TARDBP is linked to Alzheimer disease.