The Role of Neuropsychiatric Symptoms in Research Diagnostic Criteria for Neurodegenerative Diseases.

Neuropsychiatric syndromes and symptoms play increasingly important roles in research diagnostic criteria for neurodegenerative disorders. Diagnostic criteria were reviewed including those for dementia, Alzheimer's disease, mild cognitive impairment, mild behavioral impairment, prodromal Alzheimer's disease, dementia with Lewy bodies, prodromal dementia with Lewy bodies, Parkinson's disease, multiple system atrophy, frontotemporal dementia, primary progressive aphasia, progressive supranuclear palsy, corticobasal degeneration, traumatic encephalopathy syndrome, Huntington' disease, amyotrophic lateral sclerorsis. All contemporary research diagnostic criteria for neurodegenerative disorders expect those for Parkinson's disease, primary progressive aphasia, multisystem atrophy and amyotrophic lateral sclerosis include neuropsychiatric phenomena as core diagnostic criteria. There are no disease-specific neuropsychiatric symptoms; apathy and disinhibition are common in tauopathies, and rapid-eye-movement sleep behavioral disorder occurs almost exclusively in synucleinopathies. Neuropsychiatric symptoms and syndromes are increasingly integrated into research diagnostic criteria for neurodegenerative disorders; they require clinician skills for recognition; their biology is better understood as their relationships to cognitive, motor, and autonomic symptoms of neurodegenerative disorders are studied.