Isolated executive impairment and associated frontal neuropathology.

Cognitive impairment in the absence of dementia is common in elderly individuals and is most often studied in the context of an isolated impairment in memory. In the current study, we report the neuropsychological and neuropathological features of a nondemented elderly individual with isolated impairment on a test of executive function (i.e., Trail Making Test) and preserved memory, language, and visuospatial function. Postmortem studies indicated that cortical neurofibrillary tangles (NFT) varied considerably, and some regions contained large numbers of neuritic senile plaques. Semiquantitative immunohistochemistry showed higher NFT and amyloid-beta (Abeta) loads in the frontal cortex relative to the temporal, entorhinal, occipital, and parietal cortices. A survey of the entire cingulate gyrus showed a wide dispersion of Abeta42 with the highest concentration in the perigenual part of the anterior cingulate cortex; Abeta appeared to be linked with neuron loss and did not overlap with the heaviest neuritic degeneration. The current case may represent a nonmemory presentation of mild cognitive impairment (executive mild cognitive impairment) that is associated with frontal and anterior cingulate pathology and may be an early stage of the frontal variant of Alzheimer disease.