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Articulatory and language impairment heralded rapidly progressive motor neuron disease in 7 patients aged 54 to 77 years. One patient had a family history of a similar disorder. Severe nonfluent aphasia developed in all 7 patients and 4 were anarthric within a year. Other cognitive domains were impaired, yet 2 patients lived alone until 1 month before their deaths. Four died within 2 years. Abnormalities were found on electromyography, computed tomography, magnetic resonance imaging, single-photon emission computed tomography, and electroencephalography. Neuropathological examination in 3 patients showed bilateral hemispheric atrophy with neuronal loss and gliosis predominantly of superficial cortical layers. Pigmented and hypoglossal nuclei were relatively preserved. At all spinal levels there was degeneration of corticospinal tracts and loss of anterior horn cells with gliosis. Rapidly progressive aphasic dementia and motor neuron disease are a distinctive clinical entity whose nosology is poorly understood.

In this study, for the first time to our knowledge all new cases of Alzheimer's disease and other dementing illnesses have been documented in a well-defined United States community. A total of 178 patients in an average annual at-risk population of 18,991 persons over age 29 developed dementia during 1960 through 1964 in Rochester, Minnesota, yielding an average annual incidence rate of 187.5 new cases/100,000/year. The corresponding rate for clinically and/or pathologically diagnosed Alzheimer's disease (the most common cause of dementia in this community) was 123.3 new cases/100,000/year, based on 117 cases. The incidence rates for both dementia in general and Alzheimer's disease in particular rise dramatically with age. All patients were followed to death or to 1982, and the median survival was 63 months. These data include only those in the community who came to medical attention, but they yield higher rates than studies in Scandinavia, indicating a relatively high level of case ascertainment.

Threshold perception of motion of the digits was obtained in 14 normal subjects. The metacarpophalangeal joint of the index and the fifth finger of each hand and the metatarsophalangeal joint of the hallux of each foot were passively moved up and down with respect to a horizontal plane defined by the palmar or plantar surface. The motion was sinusoidal at frequencies of 0.5 and 5.0 Hz. A mpdified von Békésy paradigm similar to that used in audiometry was utilized to yield threshold levels of motion sensation. There was little difference in the thresholds obtained for the different joints. The difference between high- and low-frequency stimulation, however, was significant (p less than 0.001): the 0.5 Hz threshold was found to range from 0.8 to 1.0 degree, whereas the 5.0 Hz threshold varied from 0.4 to 0.6 degree. It is thought that motion sense is largely dependent on joint receptor contributions, but muscle and cutaneous receptors may also contribute to this proprioceptive sensation.