Apathy is associated with increased amyloid burden in mild cognitive impairment.

Apathy is the most common neuropsychiatric symptom in mild cognitive impairment (MCI) and Alzheimer's disease (AD) dementia. The authors sought to determine whether apathy is associated with cortical amyloid burden, as measured by Pittsburgh Compound B (PiB) positron emission tomography (PET), and regional hypometabolism, measured by 18F-fluorodeoxyglocuse (FDG) PET in MCI. The authors found a significant association between increased apathy (lower Apathy Evaluation Scale score) and greater cortical PiB retention independent of age, but no significant association between apathy and regional FDG metabolism. These results suggest that increased apathy is associated with greater amyloid burden but not regional hypometabolism in MCI.

Florbetapir (F18-AV-45) PET to assess amyloid burden in Alzheimer's disease dementia, mild cognitive impairment, and normal aging.

OBJECTIVE: To evaluate the performance characteristics of florbetapir F18 positron emission tomography (PET) in patients with Alzheimer's disease (AD), mild cognitive impairment (MCI), and healthy control subjects (HCs). METHODS: Florbetapir PET was acquired in 184 subjects (45 AD patients, 60 MCI patients, and 79 HCs) within a multicenter phase 2 study. Amyloid burden was assessed visually and quantitatively, and was classified as positive or negative. RESULTS: Florbetapir PET was rated visually amyloid positive in 76% of AD patients, 38% of MCI patients, and 14% of HCs. Eighty-four percent of AD patients, 45% of MCI patients, and 23% of HCs were classified as amyloid positive using a quantitative threshold. Amyloid positivity and mean cortical amyloid burden were associated with age and apolipoprotein E ε4 carrier status. CONCLUSIONS: : The data are consistent with expected rates of amyloid positivity among individuals with clinical diagnoses of AD and MCI, and indicate the potential value of florbetapir F18 PET as an adjunct to clinical diagnosis.

Maternal dementia age at onset in relation to amyloid burden in non-demented elderly offspring.

Family history (FH) of dementia is a major risk factor for Alzheimer's disease, particularly when the FH is maternal and when the age of dementia onset (AO) is younger. This study tested whether brain amyloid-beta deposition, measured in vivo with (11)C-Pittsburgh compound B (PiB), was associated with parental dementia and/or younger parental AO. Detailed FH and positron emission tomography (PiB) data were acquired in 147 nondemented aging individuals (mean age 75 ± 8). No participant had both positive maternal and paternal FH. A series of analyses revealed that those with maternal, but not paternal, FH had greater levels of PiB retention in a global cortical region than those without FH. PiB retention in maternal FH was not significantly greater than paternal FH. Younger maternal dementia AO was related to greater PiB retention in offspring, whereas younger paternal dementia AO was not. Overall, results suggest that not only is amyloid-beta burden greater in individuals with maternal FH, but also that the burden is greater in association with younger maternal AO.

Cognitive activity relates to cognitive performance but not to Alzheimer disease biomarkers.

OBJECTIVE: We aimed to determine whether there was a relationship between lifestyle factors and Alzheimer disease biomarkers. METHODS: In a cross-sectional study, we evaluated self-reported histories of recent and past cognitive activity, self-reported history of recent physical activity, and objective recent walking activity in 186 clinically normal individuals with mean age of 74 ± 6 years. Using backward elimination general linear models, we tested the hypotheses that greater cognitive or physical activity would be associated with lower Pittsburgh compound B-PET retention, greater (18)F-fluorodeoxyglucose-PET metabolism, and larger hippocampal volume, as well as better cognitive performance on neuropsychological testing. RESULTS: Linear regression demonstrated that history of greater cognitive activity was correlated with greater estimated IQ and education, as well as better neuropsychological testing performance. Self-reported recent physical activity was related to objective exercise monitoring. However, contrary to hypotheses, we did not find evidence of an association of Pittsburgh compound B retention, (18)F-fluorodeoxyglucose uptake, or hippocampal volume with past or current levels of cognitive activity, or with current physical activity. CONCLUSIONS: We conclude that a history of lifelong cognitive activity may support better cognitive performance by a mechanism that is independent of brain ß-amyloid burden, brain glucose metabolism, or hippocampal volume.