The relationship of age to prepulse inhibition and habituation of the acoustic startle response.

Prepulse inhibition (PPI) of the startle response reflects an early stage of information processing that is abnormal in schizophrenia and certain other specific neuropsychiatric disorders that are distinguished by the inability to inhibit redundant or relatively irrelevant sensory, cognitive, or motor information. The goal of the present study was to characterize the effect of normal aging on PPI and habituation of the startle response and to examine the hypothesis that normal aging is characterized by a global decline in inhibitory function. Ninety-seven non-psychiatric controls (age range 18-88) were tested for startle eyeblink response using electromyogram (EMG) recording. Startle magnitude decreased and startle latency increased with aging. PPI demonstrated an inverted U-shaped function with age (greatest PPI at intermediate ages) while there was no significant effect of age on startle habituation. The results do not support the theory that aging is associated with a general decline in inhibitory function and contrast with previous studies that have compared only extreme age groups and have found no effects of age on PPI.