Cerebral amyloid angiopathy (CAA) is characterized by amyloid beta peptide deposits within small to medium-sized blood vessels of the brain and leptomeninges. Although CAA is usually asymptomatic, it is an important cause of primary lobar intracerebral hemorrhage in the elderly [1,2]. It can occur as a sporadic disorder, sometimes in association with Alzheimer disease (AD), or as a certain familial syndrome. In addition to intracerebral hemorrhage, CAA may present with transient neurological symptoms, an inflammatory leukoencephalopathy, as a contributor to cognitive impairment, or with incidental microhemorrhages or hemosiderosis on MRI.
The incidence of cerebral amyloid angiopathy (CAA), like Alzheimer disease (AD), is strongly age dependent. Based upon a series of 784 autopsy cases, we estimated the prevalence of moderate to severe CAA as 2.3 percent for patients between the ages of 65 and 74, 8.0 percent between the ages of 75 and 84, and 12.1 percent over the age of 85 . Although sporadic, CAA-related symptoms are uncommon at ages younger than 60 to 65 they can more rarely affect individuals in their 50s as well.
There is no strong predilection for gender. Although the association of CAA with hypertension is debated, it is clear that many patients with CAA-related hemorrhage are normotensive [4-6].
Vascular amyloid deposits in sporadic cerebral amyloid angiopathy (CAA) are biochemically similar to the material comprising senile plaques in Alzheimer disease (AD) . The primary constituent of each is amyloid beta-peptide, a 39 to 43 amino acid fragment of the amyloid precursor protein. There is essentially no clinical overlap between CAA and the non-CNS systemic amyloidoses, such as primary (amyloid AL) and secondary (amyloid AA) amyloidosis.
Mutant amyloid precursor protein — Mutations in the gene that encodes the amyloid precursor protein (APP) are responsible for some cases of "presenile" CAA. While most of these mutations are also associated with at least some of the neuropathologic features of AD, at least one APP mutation (Leu34Val) has been reported to cause autosomal dominant CAA without parenchymal amyloid plaques or neurofibrillary tangles .