Neurological

Evidence of memory impairment in cerebral amyloid angiopathy

In patients with cerebral amyloid angiopathy (CAA), the presence of a memory impairment may serve as a marker of tau pathology and the integrity of the medial temporal lobe, according to study results published in Neurology.

Previous studies have shown that CAA, an angiopathy characterized by the buildup of amyloid proteins in leptomeningeal and cortical vessels, plays an important role in the development of vascular cognitive impairment and dementia and is also a common feature of Alzheimer’s disease.

The aim of the current study was to examine the neuroimaging characteristics of patients with CAA with and without objective memory impairment using tau positron emission tomography (PET).

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The study included 46 patients with CAA who underwent neuropsychological evaluation, of whom 25 had an amnestic CAA and 21 had a non-amnestic CAA. All patients completed magnetic resonance imaging (MRI) within 3 months of neuropsychological evaluation to quantify small vessel disease.

A subgroup of enrolled participants performed PET scans to estimate amyloid in vivo ([11C]-Pittsburgh compound B amyloid PET, n = 39) and tau ([18F]-flortaucipir tau-PET, n = 40) pathology.

Neuroimaging characteristics of patients with CAA with or without objective memory impairment were compared as well as demographic, clinical and cognitive characteristics.

In patients with amnestic CAA, compared to patients with non-amnestic CAA, tau-PET retention was increased in regions prone to neurodegeneration of Alzheimer’s disease (P = 0.003) and the differences persisted after monitoring the MRI markers cerebral vascular disease was significant in age and gender (P = 0.01). After adjusting for age and gender, the normalized total hippocampal volume was lower in patients with amnestic CAA than in patients with non-amnestic CAA (P <0.001).

There were no significant differences between patients with amnestic and non-amnestic CAA on other structural MRI markers or on amyloid PET binding.

The comparison of patients with CAA with a positive (21 participants) and a negative Tau-PET (19 participants) showed a lower performance in the memory domain in the former compared to the latter (P = 0.004), while the performance in other cognitive Domains were not significantly different.

The study had several limitations, including the lack of histopathological confirmation of the diagnosis of CAA and amyloid and tau pathology, small sample size, and possible selection bias since the study included patients with CAA without a history of intracerebral hemorrhage.

“Our study shows that the presence of memory impairment in patients with CAA is a promising marker of tau pathology and the integrity of the medial temporal lobe. In the absence of advanced neuroimaging technologies, this accessible clinical marker could provide relevant information about the severity and nature of the underlying pathological mechanisms in this heterogeneous population, ”concluded the study’s researchers.

reference

Schoemaker D., Charidimou A., Zanon Zotin MC, et al. Association of memory disorders with accompanying tau pathology in patients with cerebral amyloid angiopathy. Neurology. 2021; 96 (15): e1975-e1986. doi: 10.1212 / WNL.0000000000011745

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