Poster Session P1 - Diagnosis and Disease Progression - Neuropsychological

Sunday, July 18, 2004

Abstract: P1-131

Citation: NeuroBiology of Aging, Volume 25, Number S2 , July 2004, Page 132


Cognitive and Neuroanatomical Correlates for Impaired Awareness of Deficits in Mild Cognitive Impairment and Alzheimer's Disease

Asmus Vogel1,2, Steen G. Hasselbalch1,3, Morten Ziebell3, Anders Gade1,2, Jette Stokholm1, Gunhild Waldemar1

1 Memory Disorders Research Unit, Copenhagen, Denmark; 2 University of Copenhagen, Copenhagen, Denmark; 3 Neurobiology Research Unit, Copenhagen, Denmark. Contact e-mail: vogel@rh.dk

Background: Impaired awareness of deficits is common in Alzheimer's Disease (AD) and Mild Cognitive Impairment (MCI). Previous studies have found inconsistent results on the cognitive and neuroanatomical basis for impaired awareness, but dominating theories suggest that impaired awareness is dependent on frontal lobe dysfunction. Objective(s): To assess if performance on executive neuropsychological tests and regional cerebral blood flow (rCBF) in frontal cortical regions were correlated to unawareness of deficits in patients with ``amnesic MCI'' and mild AD. Methods: From a prospective study at Copenhagen University Hospital Memory Clinic including consecutively referred patients older than 60 years with MMSE scores above 19, 36 patients with AD and 30 with ``amnesic MCI'' were included. Assessments for awareness included both ratings on a categorical three-point scale and discrepancy scores between patients' and relatives' rating of memory functioning on a 20 item Memory Questionnaire (MQ). Executive functions were examined using 7 neuropsychological tests, and behavioral symptoms were assessed with Frontal Behavioral Inventory (FBI). Tc99m-HMPAO SPECT was performed in 55 patients, and rCBF expressed as ratios normalized to cerebellum was analyzed in four frontal cortical regions. Results: Awareness was equally impaired in the two groups of patients. Awareness as assessed by MQ was significantly correlated to rCBF in right dorsolateral prefrontal cortex (r = 0.33, p = 0.02) and to scores on the FBI (r = -0.45, p < 0.01). Of the 7 executive tests MQ was only correlated to the Stroop test, which was performed significantly faster but with more errors with high scores on the questionnaire. The 3 groups classified by the categorical ratings ``full'', ``shallow'' or ``no'' awareness were not characterized by differences in executive function, behavioral symptoms or frontal rCBF. Conclusions: Impaired awareness, assessed with discrepancy scores between patients' and relatives' ratings on the MQ, was associated with more behavioral symptoms and correlated with hypoperfusion in the right dorsolateral prefrontal cortex. However, a categorical rating of awareness was not sufficiently detailed to demonstrate the same correlations. No association between awareness and executive performance on neuropsychological tests were found. Whether the association between awareness and prefrontal rCBF reflects a neurobiological substrate for awareness remains to be confirmed.