Inspection time : a neuropsychophysiological test for measuring the functional integrity of the cholinergic system

Inspection time (IT) is a measure of the speed of early information processing, demonstrating reliable correlation with psychometric intelligence. We now provide evidence that it may serve as a marker for the integrity of the cholinergic system. Cholinergic agonists improve and antagonists impair IT, while modulators of the monoamine systems are without effect. Furthermore impairments in IT correlate with disease severity in Alzheimer's disease, a disorder of compromised cholinergic system function. Taken together, available data suggest that IT may be a useful physiological marker of functional status of the cholinergic system