title: Intelligence quotient-adjusted memory impairment is associated with abnormal single photon emission computed tomography perfusion.
abstract: Cognitive reserve among highly intelligent older individuals makes detection of early Alzheimer's disease (AD) difficult. We tested the hypothesis that mild memory impairment determined by IQ-adjusted norms is associated with single photon emission computed tomography (SPECT) perfusion abnormality at baseline and predictive of future decline. Twenty-three subjects with a Clinical Dementia Rating (CDR) score of 0, were reclassified after scores were adjusted for IQ into two groups, 10 as having mild memory impairments for ability (IQ-MI) and 13 as memory-normal (IQ-MN). Subjects underwent cognitive and functional assessments at baseline and annual follow-up for 3 years. Perfusion SPECT was acquired at baseline. At follow-up, the IQ-MI subjects demonstrated decline in memory, visuospatial processing, and phonemic fluency, and 6 of 10 had progressed to a CDR of 0.5, while the IQ-MN subjects did not show decline. The IQ-MI group had significantly lower perfusion than the IQ-MN group in parietal/precuneus, temporal, and opercular frontal regions. In contrast, higher perfusion was observed in IQ-MI compared with IQ-MN in the left medial frontal and rostral anterior cingulate regions. IQ-adjusted memory impairment in individuals with high cognitive reserve is associated with baseline SPECT abnormality in a pattern consistent with prodromal AD and predicts subsequent cognitive and functional decline.
authors: Department of Neurology, Brigham and Women's Hospital, Harvard Medical School, Boston, Massachusetts 02115, USA. drentz@partners.org
authors: Dorene M
authors: DM
authors: Rentz
authors: Terri J
authors: TJ
authors: Huh
authors: Lisa M
authors: LM
authors: Sardinha
authors: Erin K
authors: EK
authors: Moran
authors: John A
authors: JA
authors: Becker
authors: Kirk R
authors: KR
authors: Daffner
authors: Reisa A
authors: RA
authors: Sperling
authors: Keith A
authors: KA
authors: Johnson
mesh_terms: D000368:Aged; D001931:Brain Mapping; D002560:Cerebrovascular Circulation / Q000502:physiology; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D007091:Image Processing, Computer-Assisted; D007360:Intelligence / Q000502:physiology*; D007361:Intelligence Tests; D008297:Male; D008569:Memory Disorders / Q000000981:diagnostic imaging* / Q000503:physiopathology*; D008875:Middle Aged; D009483:Neuropsychological Tests; D010477:Perfusion / Q000379:methods*; D015899:Tomography, Emission-Computed, Single-Photon