title: Brain substrates of learning and retention in mild cognitive impairment diagnosis and progression to Alzheimer's disease.
abstract: Understanding the underlying qualitative features of memory deficits in mild cognitive impairment (MCI) can provide critical information for early detection of Alzheimer's disease (AD). This study sought to investigate the utility of both learning and retention measures in (a) the diagnosis of MCI, (b) predicting progression to AD, and (c) examining their underlying brain morphometric correlates. A total of 607 participants were assigned to three MCI groups (high learning-low retention; low learning-high retention; low learning-low retention) and one control group (high learning-high retention) based on scores above or below a 1.5 SD cutoff on learning and retention indices of the Rey Auditory Verbal Learning Test. Our results demonstrated that MCI individuals with predominantly a learning deficit showed a widespread pattern of gray matter loss at baseline, whereas individuals with a retention deficit showed more focal gray matter loss. Moreover, either learning or retention measures provided good predictive value for longitudinal clinical outcome over two years, although impaired learning had modestly better predictive power than impaired retention. As expected, impairments in both measures provided the best predictive power. Thus, the conventional practice of relying solely on the use of delayed recall or retention measures in studies of amnestic MCI misses an important subset of older adults at risk of developing AD. Overall, our results highlight the importance of including learning measures in addition to retention measures when making a diagnosis of MCI and for predicting clinical outcome.
authors.affiliation: Department of Psychiatry, University of California, San Diego, 8950 Villa La Jolla Drive Suite C101, La Jolla, CA 92037, USA. yuling@ucsd.edu
authors.forename: Yu-Ling
authors.initials: YL
authors.lastname: Chang
authors.forename: Mark W
authors.initials: MW
authors.lastname: Bondi
authors.forename: Christine
authors.initials: C
authors.lastname: Fennema-Notestine
authors.forename: Linda K
authors.initials: LK
authors.lastname: McEvoy
authors.forename: Donald J
authors.initials: DJ
authors.lastname: Hagler
authors.forename: Mark W
authors.initials: MW
authors.lastname: Jacobson
authors.forename: Anders M
authors.initials: AM
authors.lastname: Dale
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D000544:Alzheimer Disease / Q000453:epidemiology* / Q000503:physiopathology*; D001921:Brain / Q000033:anatomy & histology* / Q000503:physiopathology*; D003072:Cognition Disorders / Q000175:diagnosis* / Q000453:epidemiology*; D018450:Disease Progression; D005260:Female; D006801:Humans; D007858:Learning / Q000502:physiology*; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D009483:Neuropsychological Tests; D011237:Predictive Value of Tests; D012153:Retention, Psychology; D012720:Severity of Illness Index