What is it about?
Dendritic pathology and decrease of dendritic spine density are prominent phenomena in early cases of Alzheimer's disease, which correlate significantly with the progressive decline of the mental faculties. In previous studies we have described the pathological alterations of the dendrites and the dendritic spines in the prefrontal area of the cortex and the cerebellum. In this study we attempted to describe the morphological alterations of the dendrites and the dendritic spines, quantifying them in the acoustic and the visual cortices of eleven cases of Alzheimer's disease, applying Golgi staining and electron microscopy. In addition, describing also the ultrastructural changes of the mitochondria in the dendritic profiles and the dendritic spines we noticed that mitochondrial pathology correlates substantially with the dystrophic dendrites, the loss of dendritic branches and the pathological alteration of the dendritic spines. We would hypothesize that mitochondrial alterations may play a very important role in dendritic degeneration and the loss of dendritic spines and we should have thought that therapeutic strategies protecting the mitochondria may be beneficial in Alzheimer's disease.
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Why is it important?
Our data show significant parallel reduction of the dendritic branches and the dendritic spines in the visual and the acoustic cortices in early cases of Alzheimer's disease, a factwhichmay be directly related with the gradual impairment of visual and auditory perception of the patients. The pathology of the dendritic spineswas prominent in both of the cortical areas, the acoustic as well as the visual one. Among the pathological findings, the decrease in spine densitywas the most prominent phenomenon, which may be one of the substantial findings in the initial stage of neuronal degeneration . The dendritic varicosities also associated with distorted spines or loss of spines may be the main phenomenon of dendritic pathology in many degenerating diseases of the brain, including dementias. Axonless or unattached spines on the other hand, may be consequence of deafferentation attributed to noxious factors or to neurodegenerative conditions .
Perspectives
We could hypothesize that the mitochondrial alterations and mitochondrial dysfunction, which are closely associated with oxidative damage , may play a substantial role in dendritic and spinal degeneration. Mitochondrial dysfunction has been associated with energy crisis of the cell and excitotoxic cell death and it is considered to be of substantial importance in the cascade of phenomena, which eventually lead to apoptosis. Some observations indicate that increased oxidative damage is the earliest event in Alzheimer's disease emphasizing, therefore, the role that the dysfunction of the mitochondria plays in the pathogenesis of that progressive dementia.
Professor Stavros J Baloyannis or Balogiannis or Balojannis or Baloyiannis or Mpalogiannis
Aristotle University of Thessaloniki
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This page is a summary of: Dendritic pathology in Alzheimer's disease, Alzheimer s & Dementia, July 2009, Elsevier,
DOI: 10.1016/j.jalz.2009.05.643.
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