Jeff Evans is a senior editor with Elsevier Global Medical News. BALTIMORE — Atrophy in the temporoparietal cortex might be a common identifier of Alzheimer's disease patients that differentiates individuals who have atypical clinical presentations of the disease from those who have other types of dementia, according to a small magnetic resonance scanning study. Patients who have an atypical presentation of Alzheimer's disease (AD) but nonetheless have the amyloid-beta plaques and neurofibrillary tangles of tau protein that pathologically identify the disease have much less hippocampal atrophy than do patients who present with the typical clinical characteristics used to diagnose AD—loss of episodic memory, executive dysfunction, visuospatial and perceptual deficits, and language dysfunction—Keith A. Josephs, MD, reported at the annual meeting of the American Neurological Association. Differentiating AD from other dementias is important if treatments differ, said Dr. Josephs of the department of neurology at the Mayo Clinic, Rochester, Minn. He and his associates compared 14 atypical AD patients with 14 patients with pathologically diagnosed frontotemporal lobar degeneration (FTLD) who had the same dementia syndromes. They also compared the atypical AD patients with 14 patients who had both the typical clinical symptoms and pathological signs of AD and with 20 healthy patients as controls. In each group, patients had a mean age of about 64 years at disease onset with a mean of 3.4 years from disease onset to the time of the MRI scan. Half of the patients in each group were women. The typical AD patients showed expected areas of atrophy in the temporoparietal cortex and hippocampi. However, atypical AD patients had temporoparietal atrophy but no hippocampal atrophy. FTLD patients had anterior-temporal, some posterior-frontal, and hippocampal atrophy. “Temporoparietal atrophy may be a signature of Alzheimer's disease independent of syndromic presentation…. Hippocampal atrophy does not appear to be at least an early prominent feature of atypical Alzheimer's disease. Later on, 5-6 years down the road, as the process progresses and there's degeneration, well, you might find hippocampal atrophy then,” Dr. Josephs said.