[Olfaction and dementia. Preliminary results of a clinical and experimental study with N-propanol]

Various reports concerning the oro-alimentary ducts of dements and increasing arguments in favour of a new etiopathogenic hypothesis for Pick's disease, involving impaired zinc metabolism and histological lesions partly linked with the hodology of the olfactory system, lie at the origin of our present clinical interest in olfaction. In a first stage, using a technique based on dilution with N-propanol, we observed certain conditions permitting an evaluation of the olfactory capacities of patients with Pick's disease, senile plaque dementia and neurofibrillary degenerescense. There does not seem to be a decline in olfaction with age. Olfactory capacities in the two forms of dementia studied were distinctly inferior to those of non-dements. Olfactory habituation was more marked, especially in Pick's disease where there were also paradoxical responses which seemed to form part of a more general change in reaction to stimulus. In senile plaque dementia and neurofibrillary degenerescence the response to olfactory stimulus declines with dilution of N-propanol and lesional extension. Observation of recorded parameters (EEG, psycho-galvanic reflex, ocular movement, breathing) is useful in Pick's disease and may be difficult in senile plaque dementia and neurofibrillary degenerescence. Olfactory capacities appear to constitute an additional criterion on which to base a diagnosis of dementia. They could be used to help establish the neuro-biological bases of certain types of demential behaviour and to observe the progress of tentative therapies.