Cognition and beta-amyloid in preclinical Alzheimer's disease: Data from the AIBL study

• Published in: Neuropsychologia Vol. 49; no. 9; pp. 2384 - 2390
• Main Authors: Pike, Kerryn E., Ellis, Kathryn A., Villemagne, Victor L., Good, Norm, Chételat, Gael, Ames, David, Szoeke, Cassandra, Laws, Simon M., Verdile, Giuseppe, Martins, Ralph N., Masters, Colin L., Rowe, Christopher C.
• Format: Journal Article
• Language: English
• Published: Kidlington Elsevier Ltd 01-07-2011; Elsevier
• Subjects: Adult and adolescent clinical studies; Age Factors; Aged; Aged, 80 and over; Ageing; Alzheimer Disease - complications; Alzheimer Disease - diagnosis; Alzheimer Disease - diagnostic imaging; Alzheimer Disease - metabolism; Alzheimer Disease - pathology; Amyloid beta-Peptides - adverse effects; Amyloid beta-Peptides - metabolism; Amyloid imaging; Benzothiazoles; Biological and medical sciences; Carbon Radioisotopes; Case-Control Studies; Cerebral Cortex - diagnostic imaging; Cerebral Cortex - metabolism; Cerebral Cortex - pathology; Cerebral Cortex - physiopathology; Cognition Disorders - complications; Cognition Disorders - diagnostic imaging; Cognition Disorders - etiology; Cognition Disorders - metabolism; Cognition Disorders - pathology; Cohort Studies; Cross-Sectional Studies; Degenerative and inherited degenerative diseases of the nervous system. Leukodystrophies. Prion diseases; Early Diagnosis; Female; Humans; Longitudinal Studies; Male; Medical sciences; Memory; Middle Aged; Neurology; Neuropsychological Tests; Organic mental disorders. Neuropsychology; PiB-PET; Psychology. Psychoanalysis. Psychiatry; Psychopathology. Psychiatry; Radionuclide Imaging; Reference Values; Sex Factors; PiB-PET; Memory; Ageing; Amyloid imaging; Human; Nervous system diseases; Senescence; Alzheimer disease; Cognition; Cerebral disorder; β Amyloid protein; Central nervous system disease; Medical imagery; Degenerative disease; Elderly; Emission tomography
• ISSN: 0028-3932; 1873-3514
• DOI: 10.1016/j.neuropsychologia.2011.04.012

► Cognition and beta-amyloid (PiB PET) in preclinical phase of Alzheimer's disease. ► Impact of age, gender, education, APOE, and memory complaint. ► PiB positive females have worse memory and visuospatial performance. ► No effect of PiB in males. ► Overall, minimal effect of beta-amyloid at this phase.
The ‘preclinical’ phase of Alzheimer's disease is a future target for treatment, but additional research is essential to understand the relationship between β-amyloid burden and cognition during this time. We investigated this relationship using a large sample of apparently healthy older adults (N=177), which also enabled examination of whether the relationship differed according to age, gender, years of education, apolipoprotein E status, and the presence of subjective memory complaints. In addition to episodic memory, a range of cognitive measures (global cognition, semantic memory, visuospatial performance, and executive function) were examined. Participants were aged over 60 years with no objective cognitive impairment and came from the imaging arm of the Australian Imaging, Biomarkers, and Lifestyle (AIBL) study of ageing. 11C-PiB PET was used to measure β-amyloid burden and a PiB ‘cut-off’ level of 1.5 was used to separate participants with low PiB retention from those with high PiB retention. Thirty-three percent of participants had a PiB positive scan. PiB positive participants were 5 years older, twice as likely to carry an apolipoprotein E ɛ4 allele, and their composite episodic memory was 0.26 SD worse than PiB negative volunteers. Linear regressions with β-amyloid burden as a dichotomous predictor, revealed an interaction between β-amyloid burden and gender, as well as age and education effects, in predicting episodic memory and visuospatial performance. In females, but not in males, increased β-amyloid was related to worse episodic memory and visuospatial performance. Furthermore, an interaction between β-amyloid burden and APOE status was found in predicting visuospatial performance, whereby there was a trend for increased β-amyloid to relate to worse visuospatial performance for those without an APOE ɛ4 allele. There were no other main or interaction effects of β-amyloid on any of the other composite cognitive measures. These cross-sectional findings suggest that β-amyloid burden does not have a large effect on cognition in this subset of apparently healthy older people. The finding of gender differences deserves further research to answer definitively the important question of gender susceptibility to adverse cognitive effects from β-amyloid.