Neurobiology of neuropsychiatric symptoms in Alzheimer's disease: A critical review with a focus on neuroimaging

The objective of this critical review of the literature was to reveal the neural circuits involved in the occurrence of neuropsychiatric symptoms (NPS) in Alzheimer's disease (AD) patients through the association of these symptoms with neuroimaging findings. The search for articles was performed on PUBMED from January 2000 to May 2013, using the key words: Dementia AND BPSD; Dementia AND Neuropsychiatric Symptoms; and Dementia AND Psychosis, Delusions, Hallucinations, Agitation, Depression, Anxiety, Apathy, Euphoria, Disinhibition, Irritability, Aberrant Motor Behavior, Sleep or Eating Disorders. Forty-six articles were reviewed and important contributions, especially regarding the psychopathological concepts discussed, were also considered even if not included in this time period. The available evidence suggests the three most relevant neurobiological models for neuropsychiatric symptoms in Alzheimer's disease are the frontal-subcortical circuits, the cortico-cortical networks, and the monoaminergic system. We discussed the association of the individual symptoms or syndromes with these models.