Autosomal-dominant Alzheimer's disease: a review and proposal for the prevention of Alzheimer's disease

Abstract

Autosomal-dominant Alzheimer's disease has provided significant understanding of the pathophysiology of Alzheimer's disease. The present review summarizes clinical, pathological, imaging, biochemical, and molecular studies of autosomal-dominant Alzheimer's disease, highlighting the similarities and differences between the dominantly inherited form of Alzheimer's disease and the more common sporadic form of Alzheimer's disease. Current developments in autosomal-dominant Alzheimer's disease are presented, including the international Dominantly Inherited Alzheimer Network and this network's initiative for clinical trials. Clinical trials in autosomal-dominant Alzheimer's disease may test the amyloid hypothesis, determine the timing of treatment, and lead the way to Alzheimer's disease prevention.

Figure 1

Principal neuropathological changes in autosomal-dominant Alzheimer's disease. Sections showing amyloid-beta (Aβ)42 and PHF-1 tau detection (top to bottom): presenilin 1 (PS1) E280A (male, 62 years old, disease duration 8 years, apolipoprotein E3/3); PS1 E280A (male, 50 years old, disease duration 5 years, apolipoprotein E3/3); sporadic Alzheimer's disease (SAD) (female, 80 years old, disease duration 7 years, apolipoprotein E3/3); SAD (female, 84 years old, disease duration 13 years, apolipoprotein E4/4). All brain tissues were routinely fixed in formalin and were paraffin-embedded. Sections were 12 μm thick. Aβ42 was detected using polyclonal antibody C42 (with formic acid pretreatment), kindly provided by Dr Takaomi Saido (RIKEN Brain Science Institute, Tokyo, Japan). PHF-1 tau was detected using PHF-1 monoclonal antibody (with microwave pretreatment), kindly provided by Dr Peter Davies (Feinstein Institute of Medical Research, New York, USA).

Figure 2

Overview of dominantly inherited mutations in the amyloid precursor protein. Amyloid precursor protein (APP) is a type I integral membrane protein inserted in the cell membrane (upper part). The APP mutations are all clustered in or around the amyloid-beta (Aβ) peptide sequence, and this region is therefore displayed enlarged using the single amino acid code. White circles, mutations found; red font, resulting amino acid substitutions. Mutations cluster around the α-secretase, β-secretase and γ-secretase sites as indicated. They have various effects on the generation of Aβ as indicated, but their overall effect is an increased tendency to generate toxic species.

Figure 3

Overview of dominantly inherited mutations in presenilin 1. Presenilin contains nine transmembrane domains. The presenilin 1 mutations (red circles) are scattered over the protein, but most are in the hydrophobic domains of the protein. Green and yellow circles indicate whether the effect of the mutation on amyloid-beta (Aβ) production has been investigated: green, mutations that decrease Aβ40 production; yellow, mutations that increase Aβ42 production. In all cases, an increase of the Aβ42/Aβ40 ratio has been found.