"But the most notable changes were in the nerve cells of the cortex......., in some places the cells seemed to be broken down into formless clumps".
This description seems to be, to our knowledge, the first demonstration of abnormal nerve cells in senile dementia. Formless clumps are very like.... tangles!.
Beljahow also mentioned a process of global degeneration to explain senile dementia: Original paper
The markers of the new disease
All the markers that Alzheimer reported were well known at the time, and it is clear from his writings that he never meant to say that they were new. For example, it was the prevalent view before 1906 that in senile dementia "the destruction of the neurofibrillae appears to be more extensive than in the brain of a paralytic subject". Indeed, five months before Alzheimer's report, the American worker Fuller – whose contribution to this field has been neglected – had drawn attention to the presence of "neurofibrillar bundles in senile dementia".
Nor was the association between plaques and dementia a novelty, as it had been reported in 1887 by Beljahow, and confirmed by Redlich and Leri a few years later. Oskar Fischer, the neglected researcher from Prague, had also pointed out, in June 1907, that 'miliary necrosis' should be considered as a marker of senile dementia.