The phenotype of decreased calbindin-positive mature neurons in the hippocampus is observed in mouse models of neurodegenerative disease such as dementia with Lewy bodies (4) and Alzheimer’s disease (36), suggesting that the phenotype of iDG can be an intermediate phenotype between psychiatric and neurodegenerative diseases. The gene discussed is CALB1; the disease is early-onset autosomal dominant Alzheimer disease.