Delusions in dementias

Abstract Delusions are common yet often under-recognized symptoms in dementia of various etiologies. In the present chapter, we reviewed several clinical and epidemiological studies on the relationship among delusions and dementias. Dementia is an umbrella term encompassing a number of biological subtypes of cognitive impairment that have been linked with a series of specific behavioral changes as the disease progresses. Evidence from clinical, genetic, brain imaging, and neuropathology studies is now emerging to provide an initial understanding of the neurobiology of delusions. Discrete regional associations with a range of symptoms have been identified using indices of brain metabolism, blood flow, and brain structures, comprising hemispheric dominance. Although neuropathological studies previously emphasized the important roles of frontal amyloid-β plaques and tangle density in several types of delusions, recent evidence regarding tau pathology is emerging. Promising data regarding vascular pathology and reduced information processing speed could guide more rational psychopharmacological and psychoeducational interventions.