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Disclosure of APOE genotype for risk of Alzheimer's disease.

ABSTRACT: The apolipoprotein E (APOE) genotype provides information on the risk of Alzheimer's disease, but the genotyping of patients and their family members has been discouraged. We examined the effect of genotype disclosure in a prospective, randomized, controlled trial.We randomly assigned 162 asymptomatic adults who had a parent with Alzheimer's disease to receive the results of their own APOE genotyping (disclosure group) or not to receive such results (nondisclosure group). We measured symptoms of anxiety, depression, and test-related distress 6 weeks, 6 months, and 1 year after disclosure or nondisclosure.There were no significant differences between the two groups in changes in time-averaged measures of anxiety (4.5 in the disclosure group and 4.4 in the nondisclosure group, P=0.84), depression (8.8 and 8.7, respectively; P=0.98), or test-related distress (6.9 and 7.5, respectively; P=0.61). Secondary comparisons between the nondisclosure group and a disclosure subgroup of subjects carrying the APOE epsilon4 allele (which is associated with increased risk) also revealed no significant differences. However, the epsilon4-negative subgroup had a significantly lower level of test-related distress than did the epsilon4-positive subgroup (P=0.01). Subjects with clinically meaningful changes in psychological outcomes were distributed evenly among the nondisclosure group and the epsilon4-positive and epsilon4-negative subgroups. Baseline scores for anxiety and depression were strongly associated with post-disclosure scores of these measures (P<0.001 for both comparisons).The disclosure of APOE genotyping results to adult children of patients with Alzheimer's disease did not result in significant short-term psychological risks. Test-related distress was reduced among those who learned that they were APOE epsilon4-negative. Persons with high levels of emotional distress before undergoing genetic testing were more likely to have emotional difficulties after disclosure. (ClinicalTrials.gov number, NCT00571025.)

SUBMITTER: Green RC

PROVIDER: S-EPMC2778270 | biostudies-literature | 2009 Jul

REPOSITORIES: biostudies-literature

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Disclosure of APOE genotype for risk of Alzheimer's disease.

Green Robert C RC Roberts J Scott JS Cupples L Adrienne LA Relkin Norman R NR Whitehouse Peter J PJ Brown Tamsen T Eckert Susan LaRusse SL Butson Melissa M Sadovnick A Dessa AD Quaid Kimberly A KA Chen Clara C Cook-Deegan Robert R Farrer Lindsay A LA

The New England journal of medicine 20090701 3

<h4>Background</h4>The apolipoprotein E (APOE) genotype provides information on the risk of Alzheimer's disease, but the genotyping of patients and their family members has been discouraged. We examined the effect of genotype disclosure in a prospective, randomized, controlled trial.<h4>Methods</h4>We randomly assigned 162 asymptomatic adults who had a parent with Alzheimer's disease to receive the results of their own APOE genotyping (disclosure group) or not to receive such results (nondisclos ...[more]

PMID: 19605829

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Project description:The ε4 allele of Apolipoprotein (APOE4) is the strongest genetic risk factor for Alzheimer's disease (AD), the most common form of dementia. Cognitively normal APOE4 carriers have developed amyloid beta (Aβ) plaques and cerebrovascular, metabolic and structural deficits decades before showing the cognitive impairment. Interventions that can inhibit Aβ retention and restore the brain functions to normal would be critical to prevent AD for the asymptomatic APOE4 carriers. A major goal of the study was to identify the potential usefulness of rapamycin (Rapa), a pharmacological intervention for extending longevity, for preventing AD in the mice that express human APOE4 gene and overexpress Aβ (the E4FAD mice). Another goal of the study was to identify the potential pharmacogenetic differences in response to rapamycin between the E4FAD and E3FAD mice, the mice with human APOE ε3 allele. We used multi-modal MRI to measure in vivo cerebral blood flow (CBF), neurotransmitter levels, white matter integrity, water content, cerebrovascular reactivity (CVR) and somatosensory response; used behavioral assessments to determine cognitive function; used biochemistry assays to determine Aβ retention and blood-brain barrier (BBB) functions; and used metabolomics to identify brain metabolic changes. We found that in the E4FAD mice, rapamycin normalized bodyweight, restored CBF (especially in female), BBB activity for Aβ transport, neurotransmitter levels, neuronal integrity and free fatty acid level, and reduced Aβ retention, which were not observe in the E3FAD-Rapa mice. In contrast, E3FAD-Rapa mice had lower CVR responses, lower anxiety and reduced glycolysis in the brain, which were not seen in the E4FAD-Rapa mice. Further, rapamycin appeared to normalize lipid-associated metabolism in the E4FAD mice, while slowed overall glucose-associated metabolism in the E3FAD mice. Finally, rapamycin enhanced overall water content, water diffusion in white matter, and spatial memory in both E3FAD and E4FAD mice, but did not impact the somatosensory responses under hindpaw stimulation. Our findings indicated that rapamycin was able to restore brain functions and reduce AD risk for young, asymptomatic E4FAD mice, and there were pharmacogenetic differences between the E3FAD and E4FAD mice. As the multi-modal MRI methods used in the study are readily to be used in humans and rapamycin is FDA-approved, our results may pave a way for future clinical testing of the pharmacogenetic responses in humans with different APOE alleles, and potentially using rapamycin to prevent AD for asymptomatic APOE4 carriers.

Project description:BACKGROUND:Psychosis is a common phenomenon in Alzheimer's disease (AD). The APOE ?4 allele is the strongest genetic risk factor for the development of AD, but its association with psychosis remains unclear. OBJECTIVE:We investigated the associations between psychosis, subdivided into delusions and hallucinations, as well as APOE ?4 allele on cognitive and functional outcomes. Secondarily, we investigated the associations between APOE ?4, Lewy bodies, and psychosis. METHODS:Data from the National Alzheimer's Coordinating Center (NACC) were used. Nine hundred patients with a confirmed diagnosis of AD based on the NIA-AA Reagan were included in the analysis. Global cognition was assessed using the Mini-Mental State Exam (MMSE) and functional status was assessed using the Functional Activities Questionnaire (FAQ). Psychosis status was determined using the Neuropsychiatric Inventory Questionnaire (NPI-Q). Factorial design was used to assess the effects of psychosis and APOE ?4, as well as their interaction. RESULTS:Psychosis and the presence of APOE ?4 were both associated with lower MMSE scores, while only psychosis was associated with higher FAQ scores. Furthermore, patients with hallucinations had lower MMSE and higher FAQ scores than patients with only delusions. There was a significant interaction effect between psychosis and APOE ?4 on MMSE scores, with APOE ?4 negatively affecting patients with hallucinations-only psychosis. APOE ?4 was positively associated with the presence of Lewy body pathology, and both were found to be more prevalent in psychotic patients, with a stronger association with hallucinations. CONCLUSION:Psychosis in AD was associated with greater cognitive and functional impairments. Patients with hallucinations-with or without delusions-conferred even greater deficits compared to patients with only delusions. The APOE ?4 allele was associated with worse cognition, especially for patients with hallucination-only psychosis. APOE ?4 may mediate cognitive impairment in the hallucinations phenotype through the development of Lewy bodies. Our findings support that subtypes of psychosis should be evaluated separately.

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Disclosure of APOE genotype for risk of Alzheimer's disease.

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Disclosure of APOE genotype for risk of Alzheimer's disease.

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