Background: Bulbous neuritic changes in neuritic plaques have already been described, and
their possible effect on the clinical course of the disease has been discussed.
Objective: In our study, we focused on the location and density of these structures in patients with only
Alzheimer’s disease (AD) and patients with AD in comorbidity with synucleinopathies.
Methods: Utilizing immunohistochemistry and confocal microscopy, we evaluated differences of neocortical
and archicortical neuritic plaques and the frequency of bulbous changes in the archicortex of
14 subjects with Alzheimer’s disease (AD), 10 subjects with the Lewy body variant of Alzheimer's disease
(AD/DLB), and 4 subjects with Alzheimer's disease with amygdala Lewy bodies (AD/ALB). Also,
the progression and density of neuritic changes over the time course of the disease were evaluated.
Results: We found structural differences in bulbous dystrophic neurites more often in AD/DLB and
AD/ALB than in pure AD cases. The bulbous neuritic changes were more prominent in the initial and
progressive phases and were reduced in cases with a long clinical course.
Conclusion: Our results indicate that there is a prominent difference in the shape and composition of
neocortical and archicortical neuritic plaques and, moreover, that bulbous neuritic changes can be observed
at a higher rate in AD/DLB and AD/ALB subjects compared to pure AD subjects. This observation
probably reflects that these subacute changes are more easily seen in the faster clinical course of
AD patients with comorbidities.