We studied the accumulation of neurofibrillary tangles (NFTs) and senile plaques (SPs) in 10 Alzheimer's disease patients who had been examined during life. We counted NFTs and SPs in 13 cytoarchitectural regions representing limbic, primary sensory, and association cortices, and in subcortical neurotransmitter-specific areas. The degree of neuropathologic change was compared with the severity of dementia, as assessed by the Blessed Dementia Scale and duration of illness. We found that (1) the severity of dementia was positively related to the number of NFTs in neocortex, but not to the degree of SP deposition; (2) NFTs accumulate in a consistent pattern reflecting hierarchic vulnerability of individual cytoarchitectural fields; (3) NFTs appeared in the entorhinal cortex, CA1/subiculum field of the hippocampal formation, and the amygdala early in the disease process; and (4) the degree of SP deposition was also related to a hierarchic vulnerability of certain brain areas to accumulate SPs, but the pattern of SP distribution was different from that of NFT.

IntroductionLate-onset Alzheimer's disease (LOAD, onset age > 60 years) is the most prevalent dementia in the elderly 1 , and risk is partially driven by genetics 2 . Many of the loci responsible for this genetic risk were identified by genome-wide association studies (GWAS) [3][4][5][6][7][8] . To identify additional LOAD risk loci, the we performed the largest GWAS to date (89,769 individuals), analyzing both common and rare variants. We confirm 20 previous LOAD risk loci and identify four new genome-wide loci (IQCK, ACE, ADAM10, and ADAMTS1). Pathway analysis of these data implicates the immune system and lipid metabolism, and for the first time tau binding proteins and APP metabolism. These findings show that genetic variants affecting APP and Aβ processing are not only associated with early-onset autosomal dominant AD but also with LOAD. Analysis of AD risk genes and pathways show enrichment for rare variants (P = 1.32 x 10 -7 ) indicating that additional rare variants remain to be identified. Main TextOur previous work identified 19 genome-wide significant common variant signals in addition to APOE 9 , that influence risk for LOAD. These signals, combined with 'subthreshold' common variant associations, account for ~31% of the genetic variance of LOAD 2 , leaving the majority of genetic risk uncharacterized 10 . To search for additional signals, we conducted a GWAS metaanalysis of non-Hispanic Whites (NHW) using a larger sample (17 new, 46 total datasets) from our group, the International Genomics of Alzheimer's Project (IGAP) (composed of four AD consortia: ADGC, CHARGE, EADI, and GERAD). This sample increases our previous discovery sample (Stage 1) by 29% for cases and 13% for controls (N=21,982 cases; 41,944 controls) ( Supplementary Table 1 and 2, and Supplementary Note). To sample both common and rare variants (minor allele frequency MAF ≥ 0.01, and MAF < 0.01, respectively), we imputed the discovery datasets using a 1000 Genomes reference panel consisting of . CC-BY-NC-ND 4.0 International license peer-reviewed) is the author/funder. It is made available under a 11 36,648,992 single-nucleotide variants, 1,380,736 insertions/deletions, and 13,805 structural variants. After quality control, 9,456,058 common variants and 2,024,574 rare variants were selected for analysis (a 63% increase from our previous common variant analysis in 2013).Genotype dosages were analyzed within each dataset, and then combined with meta-analysis ( Supplementary Figures 1 and 2 and Supplementary Table 3). The Stage 1 discovery metaanalysis was first followed by Stage 2 using the I-select chip we previously developed in Lambert et al (including 11,632 variants, N=18,845) and finally stage 3A (N=6,998). The final sample was 33,692 clinical AD cases and 56,077 controls.Meta-analysis of Stages 1 and 2 produced 21 associations with P ≤ 5x10 -8 (Table 1 and Figure 1). Of these, 18 were previously reported as genome-wide significant and three of them are signals not initially described in Lambert et al: the rare R47H TREM2 coding va...

Inheritance of the apolipoprotein E (apoE) epsilon 4 allele is associated with a high likelihood of developing Alzheimer's disease (AD). The pathophysiologic basis of this genetic influence is unknown. We reasoned that understanding the influence of apoE epsilon 4 on the clinical course and neuropathological features of AD may provide tests of potential mechanisms. We carried out a prospective longitudinal study to compare the age of onset, duration, and rate of progression of 359 AD patients to apoE genotype. Thirty-one of the individuals who died during the study were available for quantitative neuropathological evaluation. Statistically unbiased stereological counts of neurofibrillary tangles (NFTs) and A beta deposits were assessed in a high-order association cortex, the superior temporal sulcus. Analysis of clinical parameters compared with apoE genotype showed that the epsilon 4 allele is associated with an earlier age of onset but no change in rate of progression of dementia. Quantitative neuropathological assessment revealed that NFTs were strongly associated with clinical measures of dementia duration and severity but not with apoE genotype. A beta deposition, by contrast, was not related to clinical features but was elevated in association with apoE epsilon 4. These results indicate that apoE epsilon 4 is associated with selective clinical and neuropathological features of AD and support hypotheses that focus on an influence of apoE epsilon 4 on amyloid deposition.

Herbicide exposure may be an effect modifier of the relation between glutathione S-transferase pi gene polymorphisms and onset age in familial PD.