Re: Explain how Al is involved in Alzheimer's disease.

Part A: Aluminum and Alzheimer
Aluminum (Al) may be taken up from various sources such as drinking water, 
aluminum containers (a minor contributor if at all), through the air we 
breathe (but there is no need to worry unless you live next door to an 
aluminum plant/mill or work there), through medication (antacids which give 
you relief from heart burn, some forms of aspirin with a special 
acid-resistant coating), antiperspirants and deoderants, (refs. 1, 5). I 
have no idea though if aluminum is involved anywhere in the production of 
candy or other sweets.

From all the information I gathered on the role of aluminum in Alzheimer’s 
disease the picture is controversial so far (ref. 2, 5, 7). Aluminum (and 
its salts) are definitely neurotoxic (i.e. they damage and kill nerve 
cells) but the changes in brain structure and nerve cells this causes in 
experimental animals** and man aren’t quite the same as seen in Alzheimer’s 
Disease (refs. 1, 5, 7). This does not imply though that aluminum does not 
cause mental impairment since it is neurotoxic after all.
   Most evidence has to be studied with care. Some clinical reports show a 
correlation between high concentrations of Al in drinking water and the 
risk of developing AD under specified circumstances such as acid pH and low 
fluoride concentration (refs. 1, 2). The chemical form in which Al is 
present might play a role as well (refs. 1, 2). Keep in mind though that 
it’s a mere statistical correlation which tells us nothing about causality. 
Most other surveys do not confirm these findings or even refute them (refs. 
1,5, 7). One should mention that risk for AD is not increased in long-term 
users of antacids (which often account for a higher intake of Al than 
through drinking water).
   The finding that large amounts of aluminum accumulate in the brains of 
AD patients is equally contended (refs. 1, 5, 7). Some critics think that 
Al in the samples is a mere artifact resulting from contamination with the 
metal contained in dust, fixing and staining solutions, etc. (refs. 1,7 ). 
   The role of aluminum in the pathogenesis, i.e. how AD is caused and what 
facilitates the development of the ailment, has not conclusively been shown 
since different studies report different results (reviewed in refs. 3, 5, 
6). Some say Al is associated with pathological structures (senile plaques, 
neurofibrillary tangles) in AD brains, others refute this or list different 
explanations (refs. 5, 7).
   All in all the aluminum hypothesis seems to rest on a rather shaky basis 
and future research will show if there is anything to it at all. 

**Historically, the whole hypothesis started out in 1965 when researchers 
injected aluminum and/or its salts into the brains of rabbits and found 
that this caused inflammation and damage of nerve cells in the brain (so 
called encephalopathy). The pathological features weren’t the same as seen 
in AD brains though. 


Some reading material (more or less technical):
1.  Doll R (1993). Review: Alzheimer’s Disease and Environmental Aluminium. 
    Age and Ageing 22: 138 - 153.
2.  Forbes WF and Hill GF (1998). Is Exposure to Aluminum a Risk Factor for 
    the Development of Alzheimer Disease? - Yes. Archives of Neurology 55: 
    740 - 741.
3.  Garruto RM and Brown P (1994). Tau protein, aluminium, and Alzheimer’s 
    Disease. [Commentary] Lancet 343: 989
4.  Hachinski V (1998). Aluminum Exposure and Risk of Alzheimer Disease. 
    Archives of Neurology 55: 742.
5.  Munoz DG (1998). Is Exposure to Aluminum a Risk Factor for the 
    Development of Alzheimer Disease? - No. Archives of Neurology 55: 737 - 
    739. [ADMIN NOTE -- THIS ARTICLE CONVINCINGLY ARGUES THAT ALUMINUM IS NOT 
          ASSOCIATED WITH ALZHEIMER'S.]
6.  Shin R-W (1997). Interaction of Aluminum with Paired Helical Filament 
    Tau Is Involved in Neurofibrillary Pathology of Alzheimer’s Disease. 
    Gerontology 43 (suppl.): 16 - 23.
7.  Storey E and Masters CL (1995). Amyloid, aluminium and the aetiology of 
    Alzheimer’s disease. The Medical Journal of Australia 163: 256 - 259.

Part B: How to determine the Al content in body tissue
Novel methods use an electron microscope ( transmission or scanning1, scanning2) 
to analyze fixed tissue samples for its components. When you focus a high 
energy electron beam onto your sample the atoms in the sample will emit 
x-rays which can be analyzed in a special detector. From the data obtained 
you can tell what elements and how much of them your sample contains.
By extrapolating, i.e. a kind of estimation based on the sample you 
analyzed, you can calculate the approximate total Aluminum content of all 
body tissues.
Alternative methods include mass spectrometry and standard quantitative 
chemical analysis (e.g. by forming chemical complexes which emit light at 
easily measurable wave lenghts.
Some references: 

at U. of Oregon (quite easy reading)
CEA Company(technical)
at Rice U.(1) and 
Rice U. (2) (technical with photos and graphics)
MicroWorld (guide to microscopy 
and microanalysis)
Various Links on 
Microscopy and Microanalysis (worldwide)

Any more questions or was this answer too technical? Contact me via email.