Genetic influences on prepulse inhibition of startle reflex in humans.

Prepulse inhibition (PPI) is a suppression of the startle reflex that occurs when an intense startling stimulus is preceded by a weaker 'prepulse' stimulus. PPI deficits have been implicated in the biological bases of schizophrenia and some other neuropsychiatric disorders and proposed as a possible biological marker (endophenotype) for genetic studies. However, little is known about the genetic determination of PPI in humans. We examined acoustic eye-blink startle reflex and PPI in 142 young female twins (40 monozygotic and 31 dizygotic pairs) and conducted a biometrical genetic analysis using structural equation modeling. PPI showed significant heritability suggesting that over 50% of PPI variance in this sample can be attributed to genetic factors. Baseline startle magnitude showed higher heritability (about 70%).