title: Neurobiology of delusions, memory, and insight in Alzheimer disease.
abstract: OBJECTIVE
  Delusional thoughts are common among patients with Alzheimer disease (AD) and may be conceptually linked to memory deficits (cannot recall accurate information, which leads to inaccurate beliefs) and poor insight (unable to appreciate the illogic of beliefs). This study's goals were to examine the clinical associations among delusions, memory deficits, and poor insight; explore neurobiologic correlates for these symptoms; and identify shared mechanisms.
  
  
  METHODS
  In a cross-sectional analysis, 88 outpatients with AD (mean Mini-Mental State Exam score: 19.3) were studied. Delusional thoughts were assessed with the Neuropsychiatric Inventory, level of inaccurate insight was assessed with the Neurobehavioral Rating Scale, and memory was assessed with the Mattis Dementia Rating Scale memory subscale. (18)F-fluorodeoxyglucose positron emission tomography was used to measure regional cortical metabolism. Relationships between clinical ratings and regional cortical metabolic activity (voxel-based) were assessed using SPM2.
  
  
  RESULTS
  Patients with delusions had lower Dementia Rating Scale memory subscale scores. Neurobehavioral Rating Scale inaccurate insight scores were no different in those with and without delusions. Cortical metabolic activity was lower in the right lateral frontal cortex, orbitofrontal cortex, and bilateral temporal cortex in patients with delusions. Low cortical metabolic activity in the right lateral, inferior, and medial temporal cortex was associated with poorer memory. This region partially overlapped the region of hypometabolism associated with delusions. In contrast, low cortical metabolic activity in bilateral medial frontal cortex was associated with poor insight.
  
  
  CONCLUSIONS
  Delusions in AD are associated with dysfunction in specific frontal and temporal cortical regions. Delusions are partially clinically and neurobiologically linked to memory deficits but not to poor insight.
authors.affiliation: Brain, Behavior, and Aging Research Center, VA Greater Los Angeles Healthcare System, Los Angeles, CA; Department of Psychiatry & Biobehavioral Sciences, David Geffen School of Medicine at UCLA, Los Angeles, CA. Electronic address: dsultzer@ucla.edu.
authors.forename: David L
authors.initials: DL
authors.lastname: Sultzer
authors.affiliation: Brain, Behavior, and Aging Research Center, VA Greater Los Angeles Healthcare System, Los Angeles, CA.
authors.forename: Lorraine P
authors.initials: LP
authors.lastname: Leskin
authors.affiliation: Brain, Behavior, and Aging Research Center, VA Greater Los Angeles Healthcare System, Los Angeles, CA; Department of Psychiatry & Biobehavioral Sciences, David Geffen School of Medicine at UCLA, Los Angeles, CA.
authors.forename: Rebecca J
authors.initials: RJ
authors.lastname: Melrose
authors.affiliation: Brain, Behavior, and Aging Research Center, VA Greater Los Angeles Healthcare System, Los Angeles, CA; Department of Psychiatry & Biobehavioral Sciences, David Geffen School of Medicine at UCLA, Los Angeles, CA.
authors.forename: Dylan G
authors.initials: DG
authors.lastname: Harwood
authors.affiliation: Brain, Behavior, and Aging Research Center, VA Greater Los Angeles Healthcare System, Los Angeles, CA.
authors.forename: Theresa A
authors.initials: TA
authors.lastname: Narvaez
authors.affiliation: Brain, Behavior, and Aging Research Center, VA Greater Los Angeles Healthcare System, Los Angeles, CA.
authors.forename: Timothy K
authors.initials: TK
authors.lastname: Ando
authors.affiliation: Nuclear Medicine Service, VA Greater Los Angeles Healthcare System, Los Angeles, CA; Department of Physics, University of California, Irvine, CA.
authors.forename: Mark A
authors.initials: MA
authors.lastname: Mandelkern
mesh_terms: D000368:Aged; D000544:Alzheimer Disease / Q000150:complications / Q000378:metabolism / Q000523:psychology*; D001921:Brain / Q000378:metabolism; D032882:Comprehension; D003430:Cross-Sectional Studies; D003702:Delusions / Q000209:etiology* / Q000378:metabolism / Q000523:psychology; D005260:Female; D006801:Humans; D008297:Male; D008569:Memory Disorders / Q000209:etiology* / Q000378:metabolism / Q000523:psychology; D059906:Neuroimaging; D009483:Neuropsychological Tests; D049268:Positron-Emission Tomography
keywords: Alzheimer disease; FDG-PET; cerebral metabolism; delusions; insight; memory
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