  In 2006 Mom\v{c}ilovi\'c et al. measured radioactvity levels of 210Po and
210Bi by alpha- and beta-measurements resp. to determine the natural
distribuion of environmental radon daughters in the different brain areas of an
Alzheimer Disease victim. We show that gamma-ray spectrometry of the mother
nucleus 210Pb can be used. It is a direct measurement without tampering with
the sample. However, because this technique is far less sensitive than alpha-
and beta-spectrometry, activity values previously published were out-of-reach
for gamma-ray spectrometry. This is no longer the case with our ultra-low
background high purity Ge detectors which have been developed in the frame of
the neutrino experiments. To ascertain this possibility, ten brain samples from
Alzheimer patients and blanks as well as 10 samples of brain tumors have been
investigated and results were cross-checked with two different spectrometers.
Localization of the samples in the brain was not known to avoid biased
interpretation of the results. Data taking lasted between 1 and 4 weeks for
each sample. All ten Alzheimer/blank samples were below the limit of detection
(LOD), 3 out of the 10 tumors lead to positive results (3.8 to 4.9 mBq/g of
210Pb) with a statistical significance of at least 3 standard deviations.
Potential followup of this method is to enhance the detector sensitivity,
having the spectrometer installed in an underground laboratory such as the one
in Modane under the Alps where the background noise is 30- fold less than at
the present location in Bordeaux. The final aim is to map a brain in
collaboration with Alzheimer/Parkinson experts.
