I ran across this short description of AgD (argyrophilic grain disease) recently on the Alzheimer Europe website. I’ve been sharing it with the folks I know whose family members are diagnosed upon brain autopsy with a neurodegenerative disease (such as PSP or CBD) *plus* AgD.
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http://www.alzheimer-europe.org/Dementi … isease-AGD
Argyrophilic Grain Disease (AGD)
Neuro-Degenerative Diseases
by André Delacourte & Kurt Jellinger
General outline
New disease, which is not fully characterised. A sporadic late-onset form of dementia characterised by a neuro-degenerative process, which mainly affects limbic structures (amygdala, hippocampus and mediobasal temporal/entorhinal cortex).
It is named after silver-staining (argyrophilic) grains or coiled bodies within the cytoplasm of neurons that consist mainly of tau protein isoforms with four microtubule-binding repeates (4-R tau).
Synonym: Braak’s disease
Symptoms and course
Reduction of short-term memory, disorders of word finding, disorders of reading and writing, disorientation, behavioural disturbances (personality changes, emotional disorders with aggression and ill-temper) may precede or follow memory failure. Clinically it is hard to distinguish from late-onset AD.
The age of onset is around 70 years old. The duration of the disease is between 4 and 8 years.
Causes and risk factors
Neuron degeneration likely associated with dysfunction of tau protein. Grains are composed of abnormally phosphorylated tau protein with 4 repeats. Recent studies indicate that tau protein dysfunction in AGD in contrast to other 4-R-tauopathies (progressive supranuclear palsy, corticobasal degeneration).
Genetics
The disease arises irrespective of the genetic background regarding tau H1 or H2 haplotypes, at the opposite of PSP and CBD (Miserez A. R. et al, 2003). Lack of relationship with apolipoprotein E4.
Frequency
1 to 5% of AD patients (Togo T. et al, 2002).
Diagnostic procedures
It is almost impossible to distinguish from late-onset Alzheimer’s disease. The diagnosis is almost entirely made by post-mortem examination. AGD lesions are found in about 5% of Alzheimer’s disease (Togo T. et al, 2002).
Last Updated: Friday 09 October 2009