On disentangling states versus traits: demonstration of a new technique using the Alzheimer's disease assessment scale.

Part of the challenge in research on degenerative neurologic disease relates to distinguishing those measurements that essentially describe patient characteristics stable across the course of illness (traits) from those that vary systematically within subjects (states), particularly those specifically related to stage or duration of illness. A components-of-variance approach was used to examine the state versus trait aspects of the Alzheimer's Disease Assessment Scale (ADAS) Cognitive and Noncognitive subscales, a clinical instrument frequently used in research on Alzheimer disease. Subjects were 190 patients with probable AD followed longitudinally.

The risks and implications of excessive daytime sleepiness in resident physicians.

Purpose: To assess the levels of physiologic and subjective sleepiness in residents in three conditions: (1) during a normal (baseline) work schedule, (2) after an in-hospital 24-hour on-call period, and (3) following a period of extended sleep.

Method: In 1996, a within-subjects, repeated-measures study was performed with a volunteer sample of 11 anesthesia residents from the Stanford University School of Medicine using three separate experimental conditions. Sixteen residents were recruited and 11 of the 16 completed the three separate experimental conditions.

CSF hypocretin-1 levels in schizophrenics and controls: relationship to sleep architecture.

Hypocretins/orexins are newly identified peptides of hypothalamic origin. Hypocretin deficiency is involved in the sleep disorder narcolepsy, suggesting the importance of hypocretin neurotransmission for the regulation of sleep. Hypocretin is known to excite midbrain dopaminergic neurons and to induce hyperactivity and stereotypy in animals.