Applications of neutron activation analysis to the study of age-related neurological diseases

Although the etiology and pathogenesis of Alzheimer's disease, Pick's disease, and amyotrophic lateral sclerosis are still unknown, it has been suggested that perturbations in element metabolism may play a role. Even if not causative factors, these imbalances may prove to be markers that could aid in diagnosis. We have employed a sequential neutron activation analysis (NAA) procedure to determine elemental concentrations in brain, hair, fingernails, blood, and cerebrospinal fluid (CSF) of these patients and age-matched controls. Samples are first irradiated with accelerator-produced 14-MeV neutrons for determination of nitrogen and phosphorus, then with reactor thermal neutrons for the instrumental determination of 16-18 minor and trace elements, and, finally, reactor-irradiated again, followed by a rapid radiochemical separation procedure (RNAA) to determine four additional elements. Major advantages of NAA are: (1) its simultaneous multielement capability; (2) the relative freedom from reagent and laboratory contamination; (3) the absence of major matrix effects; and (4) an adequate sensitivity for most elements of interest. Ranges of concentrations by INAA and RNAA in selected control tissues and interelement correlations in control brain are presented to illustrate results obtained by the procedure. Longitudinal studies of tissues from Alzheimer's disease (AD) and amyotrophic lateral sclerosis (ALS) patients are still in progress.