Caselli, Richard J.

Background: Brain imaging measurements can provide evidence of possible preclinical Alzheimer’s disease (AD). Their ability to predict individual imminent clinical conversion remains unclear. Objective: To investigate the ability of pre-specified volumetric magnetic resonance imaging (MRI) and fluorodeoxyglucose positron emission tomography (FDG-PET) measurements to predict which cognitively unimpaired older participants would subsequently progress to amnestic mild cognitive impairment (aMCI) within 2 years. Methods: From an apolipoprotein E4 (APOE4) enriched prospective cohort study, 18 participants subsequently progressed to the clinical diagnosis of aMCI or probable AD dementia within 1.8±0.8 years (progressors); 20 participants matched for sex, age, education, and APOE allele dose remained cognitively unimpaired for at least 4 years (nonprogressors). A complementary control group not matched for APOE allele dose included 35 nonprogressors. Groups were compared on baseline FDG-PET and MRI measures known to be preferentially affected in the preclinical and clinical stages of AD and by voxel-wise differences in regional gray matter volume and glucose metabolism. Receiver Operating Characteristic, binary logistic regression, and leave-one-out procedures were used to predict clinical outcome for the a priori measures. Results: Compared to non-progressors and regardless of APOE-matching, progressors had significantly reduced baseline MRI and PET measurements in brain regions preferentially affected by AD and reduced hippocampal volume was the strongest predictor of an individual’s imminent progression to clinically significant memory decline (79% sensitivity/78% specificity among APOE-matched cohorts). Conclusion: Regional MRI and FDG-PET measurements may be useful in predicting imminent progression to clinically significant memory decline.

Background: The association between longitudinal changes in serum glucose level and longitudinal changes in [ 18 F] Fluorodeoxyglucose-PET (FDG PET) measurements of Alzheimer’s disease (AD) risk are unknown. Objective: To investigate whether variation in serum glucose levels across time are associated with changes in FDG PET measurements of cerebral metabolic rate for glucose (rCMRgl) in brain regions preferentially affected by Alzheimer’s disease (AD). Methods: Participants are a subset of a prospective cohort study investigating FDG PET, apolipoprotein E (APOE) ɛ4, and risk for AD which includes data from baseline, interim, and follow up visits over 4.4±1.0-years. An automated brain-mapping algorithm was utilized to characterize and compare associations between longitudinal changes in serum glucose levels and longitudinal changes in rCMRgl. Results: This study included 80 adults aged 61.5±5 years, including 38 carriers and 42 non-carriers of the APOE ɛ4 allele. Longitudinal increases in serum glucose levels were associated with longitudinal CMRgl decline in the vicinity of parietotemporal, precuneus/posterior cingulate, and prefrontal brain regions preferentially affected by AD ( p < 0.05, corrected for multiple comparisons). Findings remained significant when controlled for APOE ɛ4 status and baseline and advancing age. Conclusions: Additional studies are needed to clarify and confirm the relationship between longitudinal changes in peripheral glucose and FDG PET measurements of AD risk. Future findings will set the stage on the use of FDG PET in the evaluation of possible interventions that target risk factors for the development of AD.

Background/Objectives Behavioral problems in individuals with Alzheimer's disease ( AD ) impose major management challenges. Current prevention strategies are anchored to cognitive outcomes, but behavioral outcomes may provide another, clinically relevant opportunity for preemptive therapy. We sought to determine whether personality changes that predispose to behavioral disorders arise during the transition from preclinical AD to mild cognitive impairment ( MCI ). Design Longitudinal observational cohort study. Setting Academic medical center. Participants Members of an apolipoprotein E ( APOE ) ɛ4 genetically enriched cohort of Maricopa County residents who were neuropsychiatrically healthy at entry (N = 277). Over a mean interval of 7 years, 25 who developed MCI and had the Neuroticism, Extraversion, and Openness Personality Inventory—Revised ( NEO ‐ PI ‐R) before and during the MCI transition epoch were compared with 252 nontransitioners also with serial NEO ‐ PI ‐R administrations. Intervention Longitudinal administration of the NEO ‐ PI ‐R and neuropsychological test battery. Measurements Change in NEO ‐ PI ‐R factor scores (neuroticism, extraversion, openness, agreeableness, conscientiousness) from entry to the epoch of MCI diagnosis or an equivalent follow‐up duration in nontransitioners. Results NEO ‐ PI ‐R neuroticism T‐scores increased significantly more in MCI transitioners than in nontransitioners (mean 2.9, 95% confidence interval ( CI ) = 0.9–4.9 vs 0, 95% CI = −0.7–0.7, P = .02), and openness decreased more in MCI transitioners than in nontransitioners (−4.8, 95% CI = −7.3 to −2.4 vs −1.0, 95% CI = −1.6 to −0.4, P < .001). Concurrent subclinical but statistically significant changes in behavioral scores worsened more in MCI transitioners than nontransitioners for measures of depression, somatization, irritability, anxiety, and aggressive attitude. Conclusion Personality and subclinical behavioral changes begin during the transition from preclinical AD to incident MCI and qualitatively resemble the clinically manifest behavioral disorders that subsequently arise in individuals with frank dementia.

Introduction: This study set out to clarify the differential acute cognitive impact of lorazepam based on varying genetic risk for Alzheimer disease. Methods: Fifty-seven cognitively unimpaired individuals aged 51 to 88, genotyped according to apolipoprotein E (APOE) and translocase of outer mitochondrial membrane (40 homolog) poly-T lengths, completed cognitive testing before, 2.5 and 5 hours after receiving a 1 mg dose of lorazepam. Results: Post-lorazepam, there were significant (P<0.05) declines from baseline in memory, psychomotor processing speed, and executive function. At 2.5 hours, the magnitude of this lorazepam-induced cognitive change was significantly greater in the APOE3/4 group than in the APOE3/3 group for tests of working memory and visuospatial memory/executive function. At 5 hours postchallenge, verbal memory and working memory deficits persisted in the APOE3/4 group compared with the APOE3/3 group. At 5 hours after lorazepam challenge, as compared with the very long/very long group, the short/short group performed slightly worse on a test of working memory (P<0.05), but no other differences were observed among translocase of the outer mitochondrial membrane 40 homolog poly-T variant groups. Discussion: The lorazepam challenge may be unmasking presymptomatic cognitive dysfunction associated with APOE4 carriage.