Abstract
In evaluating the pathophysiology of neuropsychiatric disorders, it is helpful to take account of research on neurodegenerative diseases showing psychiatric symptoms, such as Alzheimer’s disease or dementia with Lewy bodies. Recent pathological studies have mostly focused on the neuronal circuits associated with psychiatric features, especially the mesolimbic dopaminergic pathway. For example, primary age‐related tauopathy, one of tauopathies characterized by pathological aggregation of tau protein, is known to present with delusions, and it has been suggested that increased levels of phosphorylated tau in the nucleus accumbens are associated with psychiatric symptoms. Furthermore, recent clinicopathological studies of monoaminergic systems indicate the association of nigrostriatal degeneration with depression across the Lewy body disease spectrum. Here, I review studies of age‐related pathologies linked to psychiatric symptoms, focusing on neuronal circuits, including our recent pathological studies of psychiatric disorders.
