Is there a typical pattern of brain SPECT imaging in Alzheimer's disease?

The identification of new nosological forms such as Lewy body disease (LBD) requires a re-evaluation of the patterns observed in brain functional imag ing in the various forms of dementia. We studied 60 demented patients, divi ded into three groups and fulfilling the clinical criteria for Alzheimer's disease (AD), LBD and frontotemporal dementia (FTD), using Tc-HMPAO and a b rain-dedicated SPECT system. After normalisation we applied a cut-off at tw o levels according to previously established criteria. We reaffirmed the al ready established data concerning FTD (mainly a bilateral frontal decrease) and for LBD (a severe diffuse decrease in the frontal regions and also in the posterior association cortex). In contrast, the decrease in AD was stri ctly limited to the parieto-occipital cortex, irrespective of the severity of the cognitive decline. We hypothesise that the major simplification conc erning the pattern observed in AD can be explained by the fact that patient s suffering from LBD have previously been included in the groups of AD pati ents. Copyright (C) 2001 S. Karger AG, Basel.