AIIMS November 2011 – MCQ 189
Which of the following is false regarding Alzheimer’s disease?
A. Number of neurofibrillary tangles correlates with severity of disease
B. Number of neurofibrillary tangles correlates with dementia
C. ?
D. ?
Please contribute to the discussion by posting the answer with references and pointing out the errors in the question!
One Comment
Our knowledge of the etiology and pathogenesis of Alzheimer’s disease is limited. The most conspicuous changes seen in the brain are deposits of insoluble proteins in both extracellular and intraneuronal locations. The extracellular deposits consist primarily of a specific A4 amyloid protein. The significance of these deposits remains to be determined, as they are often found in the cerebral cortex of non-demented elderly persons. More telling is the gradual accumulation of insoluble fibrous material within some neurons that consists mainly of abnormally phosphorylated tau protein. Six stages of increasingly severe cortical destruction can be distinguished. Stages I and II are characterized by neurofibrillary changes that are largely confined to the transentorhinal region, whereas stages III and IV are marked by severe involvement of both the entorhinal and transentorhinal regions. Isocortical destruction occurs during stages V and VI. This progression in cortical pathology correlates with the gradual worsening of clinical symptoms.
http://www.ncbi.nlm.nih.gov/pubmed/8740983
NFTs are composed of silver-staining neuronal cytoplasmic fibrils composed of abnormally phosphorylated tau () protein; they appear as paired helical filaments by electron microscopy. Tau binds to and stabilizes microtubules, supporting axonal transport of organelles, glycoproteins, neurotransmitters, and other important cargoes throughout the neuron. Once hyperphosphorylated, tau can no longer bind properly to microtubules and its functions are disrupted.
Harrison’s Online
Neuritic plaques and neurofibrillary changes are found in all the association areas of the cerebral cortex, but it is the neurofibrillary tangles and quantitative neuronal loss, not the amyloid plaques, that correlate best with the severity of the dementia (Arriagada et al). If any part of the brain is disproportionately affected, it is the hippocampus, particularly the CA1 and CA2 zones (of Lorente de Nó) and the entorhinal cortex, subiculum, and amygdala.
Adams and Victor’s Neurology
So i guess the answer is A