A pilot study measuring aluminum in bone in Alzheimer's and control subjects using in vivo neutron activation analysis

Aluminum, being the most abundant metal in the earth's crust, is widely distributed in the environment, and is routinely taken up by the human body through ingestion and inhalation. Aluminum is not considered an essential element and it can be toxic in high concentrations. Most of the body burden of aluminum is stored in the bones. Aluminum has been postulated to be involved in the causality of Alzheimer's disease. A system for non-invasive measurement of bone aluminum using the in vivo neutron activation analysis technique has been developed and previously reported in the literature by our group. The results are reported as ratio of Al to Ca in order to eliminate the variations in beam parameters and geometry as well as the physical variations among the subjects such as size of the hand and bone structure. This pilot study included 30 subjects, 15 diagnosed with Alzheimer's disease in mild and moderate stages and 15 control subjects, all of whom were 60 years of age or older. The mean value of aluminum for the control group was 2.7±8.2μg Al/g Ca (inverse-variance weighted mean 3.5±0.9μg Al/g Ca) and for the Alzheimer's disease subjects was 12.5±13.1μg Al/g Ca (inverse-variance weighted mean 7.6±0.6μg Al/g Ca). The difference between the mean of the Alzheimer's disease group and the mean of the control group was 9.8±15.9μg Al/g Ca, with a p-value of 0.02. An age-dependent linear increase in bone aluminum concentration was observed for all subjects. The difference in serum aluminum levels between the two groups did not reach significance.