Neurology: the perception of letter fragments in patients with pathologically confirmed Lewy bodies or Alzheimer's disease dementia

Patients with dementia with Lewy bodies perform worse on visual perception tests than those with Alzheimer's disease, but the clinical application of these tests is unclear because there are often clinically diagnosed groups in studies that may inadvertently cross-contaminate Lewy body disease (LBD) with pure AD pathology, employ experimental tests that are not easily adapted for clinical use, and cannot examine the relationship between
LBD pathological severity and degree of cognitive impairment.
A study published in Neurology sought to determine whether performance on a widely used test of visual manipulation effectively distinguishes between patients with LBD or AD confirmed by autopsy and correlates
with the severity of LBD pathology.

Patients with mild to moderate dementia (n=42) and cognitive health controls (n=22) underwent a fractional letter test, in which they identified the alphabet with 70% random visual deterioration and underwent additional visuospatial and episodic memory tests
.
At autopsy, patients with dementia were shown to have LBD (n=19), all with AD, or only AD (n=23).

The severity of α-synuclein lesions in the hippocampus and cerebral cortex is graded
in order.

The fragment letter test performance can effectively distinguish LBD patients with mild to moderate stages of dementia from those with AD-only pathology, even when LBD is associated with significant AD pathology, and may also be helpful in assessing the severity
of cortical α-synuclein pathology in LBD patients.

Sources: Salmon DP, Smirnov DS, Coughlin DG, et al.
Perception of Fragmented Letters by Patients With Pathologically Confirmed Dementia With Lewy Bodies or Alzheimer Disease [published online ahead of print, 2022 Aug 26].
Neurology.
2022; 10.
1212/WNL.
0000000000201068.
doi:10.
1212/WNL.
0000000000201068