Objective: To identify factors influencing age at symptom onset and disease course in autosomal dominant Alzheimer disease (ADAD), and develop evidence-based criteria for predicting symptom onset in ADAD.Methods: We have collected individual-level data on ages at symptom onset and death from 387 ADAD pedigrees, compiled from 137 peer-reviewed publications, the Dominantly Inherited Alzheimer Network (DIAN) database, and 2 large kindreds of Colombian (PSEN1 E280A) and Volga German (PSEN2 N141I) ancestry. Our combined dataset includes 3,275 individuals, of whom 1,307 were affected by ADAD with known age at symptom onset. We assessed the relative contributions of several factors in influencing age at onset, including parental age at onset, age at onset by mutation type and family, and APOE genotype and sex. We additionally performed survival analysis using data on symptom onset collected from 183 ADAD mutation carriers followed longitudinally in the DIAN Study.Results: We report summary statistics on age at onset and disease course for 174 ADAD mutations, and discover strong and highly significant (p , 10 216 , r 2 . 0.38) correlations between individual age at symptom onset and predicted values based on parental age at onset and mean ages at onset by mutation type and family, which persist after controlling for APOE genotype and sex.Conclusions: Significant proportions of the observed variance in age at symptom onset in ADAD can be explained by family history and mutation type, providing empirical support for use of these data to estimate onset in clinical research. Researchers have identified more than 230 different autosomal dominant Alzheimer disease (ADAD) mutations located in the genes for amyloid precursor protein (APP), presenilin 1 (PSEN1), and presenilin 2 (PSEN2), including the canonical case discovered by Alois Alzheimer.1 There are significant differences between mutation types in age at symptom onset, and many result in onset as early as the third or fourth decade of life.2,3 Some families carrying an identical ADAD mutation can have significantly different ages at onset, suggesting the presence of other genetic or environmental modifiers of the disease process.4,5 APOE genotype was found to slightly modify age at onset in 2 ADAD kindreds, 5,6 although it is not yet clear whether this is the case for ADAD in general. The factors influencing symptom onset and progression in From the

Background To evaluate the prevalence rates of non-amnestic neurological symptoms of autosomal dominant Alzheimer’s disease (ADAD) in the DIAN Observational Study (DIAN–OBS) and the published literature. Analyses were conducted to clarify the prevalence of neurological manifestations of ADAD mutation carriers as a group. Methods Using the DIAN-OBS study database and 189 peer-reviewed publications on ADAD families, we extracted individual-level data on age of symptom onset, disease course from onset to death, and the presence of fourteen neurological findings that have been reported in association with ADAD and included symptomatic subjects only. The primary outcomes were the rates of various neurological symptoms and the contribution of age and specific mutations on the prevalence of the neurological symptoms. Analyses were done using descriptive statistics, comparisons of means and frequencies and multivariable linear regression. Findings Our meta-analysis dataset includes 1228 affected individuals, with detailed clinical descriptions of 753. The DIAN–OBS dataset included 107 individuals with detailed clinical data. The most prevalent non-amnestic cognitive manifestations in DIAN were those typical of mild-moderate Alzheimer’s disease, including visual agnosia (95% CI 45·7%–64·6%), aphasia (43·8%–62·7%), and behavioral changes (51·5%–70·0%). The prevalence of non-amnestic cognitive manifestations from the published literature were (95% CI 3·9%–7·2%) for visual agnosia, (20%–26%) for aphasia, and (28·4%–35·1%) for behavioral changes. Prevalence of non-cognitive neurological manifestations in DIAN was low, including myoclonus and spasticity (3·8%–15·0%), seizures (0·5%–9·1%) and moderate for parkinsonism (5·3%–17·1%). Whereas, in the published literature the prevalence was (95% CI 16·6%–22·2% and 12·5%–17·6%) for myoclonus and spasticity, (10·1%–15·0%) for parkinsonism, and (17·4%–23·2%) for seizures. Age of onset appears to influence the prevalence of several non-cognitive manifestations in both groups, stroke being more prevalent at older ages of onset with motor symptoms being more prevalent at younger age of onset and at an older age of onset. Further, symptoms were overall more common in later clinical stages of disease. Interpretation Comparing the prevalence of non-amnestic and non-cognitive clinical features in DIAN with the published literature indicates that previous reports of non-cognitive features are likely overestimated whereas DIAN identifies higher non-amnestic cognitive symptoms in addition to memory impairment. The non-cognitive clinical manifestations of AD appear to be in a minor fraction of mild-moderate ADAD and is likely influenced by disease severity, environmental and genetic factors in addition to genetic status. The results of this work clarify the clinical presentations of ADAD including the effects of age and disease stage. Attention to these neurologic symptoms and screening for ADAD mutations are warranted if present. Future work is needed to determine the factors which caus...

DESIGN, SETTING, AND PARTICIPANTSWe performed univariate and multivariable analyses of 338 lumbar punctures in the Dominantly Inherited Alzheimer Network observational study using linear mixed models, adjusting for participant-level and family-level random effects. MAIN OUTCOMES AND MEASURESWe directly evaluated associations of 3 post-lumbar puncture outcomes (immediate postprocedural headache, PDPH at 24-hour follow-up, and PDPH receiving a therapeutic blood patch) with participant age and sex, positioning, collection method, needle size, needle insertion site, and cerebrospinal fluid (CSF) volume collected. RESULTSThe incidence of adverse events included 73 immediate postprocedural headaches (21.6%), 59 PDPHs at 24-hour follow-up (17.5%), and 15 PDPHs receiving a therapeutic blood patch (4.4%). Greater volume of CSF collected was associated with increased risk of immediate postprocedural headache, largely owing to a nonlinear increase in risk on collection of volumes above 30 mL (odds ratio, 3.73 for >30 mL and 0.98 for <17 mL). In contrast, collection of higher volumes showed a protective effect in decreasing rates of PDPH at 24-hour follow-up and rates of PDPH receiving a therapeutic blood patch (odds ratio, 0.35 per 10 mL). Although differences in needle size did not reach statistical significance, no participant in the 24G needle group received a therapeutic blood patch compared to 8 of 253 for the larger 22G needles. CONCLUSIONS AND RELEVANCEFactors that acutely lower CSF pressure (eg, seated positioning or extracting very high volumes of CSF) may be associated with transient post−lumbar puncture headache, without increasing rates of persistent PDPH or therapeutic blood patch. Collection of up to 30 mL of CSF appears to be well tolerated and safe.

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Genetic studies have demonstrated very high heritability for Alzheimer's disease (AD) risk in humans; however, these genetic contributions have proven extremely challenging to map in large studies of AD patients. Processing of the amyloid precursor protein (APP) to produce amyloidbeta (Aβ) peptide is increasingly believed to be of central importance in AD pathogenesis. Intriguingly, mice from the C57BL/6J and DBA2/J inbred strains carrying the R1.40 APP transgene produce identical levels of unprocessed APP, but demonstrate significant, heritable differences in Aβ levels. To identify specific loci responsible for the observed genetic control of Aβ metabolism in this model system, we have performed a whole-genome quantitative trait locus (QTL) mapping experiment on a total of 516 animals from a C57BL/6JxDBA/2J intercross using a dense set of SNP genetic markers. Our studies have identified three loci on mouse chromosomes 1, 2, and 7 showing significant or suggestive associations with brain Aβ levels, several of which contain regions syntenic to previous reports of linkage in human AD.