Chronic cannabis use is associated with attention-modulated reduction in
prepulse inhibition of the startle reflex in healthy humans
Karina K. Kedzior1*
Matthew Martin-Iverson2
1 Centre for Clinical Research in Neuropsychiatry, Graylands Hospital, Mt
Claremont WA 6190, Australia, and School of Medicine and Pharmacology, Faculty
of Medicine and Dentistry, University of Western Australia, Crawley WA 6009, Australia.
2 School of Medicine and Pharmacology, Faculty of Medicine and Dentistry,
University of Western Australia, Crawley WA 6009, Australia and Centre for
Clinical Research in Neuropsychiatry, Graylands Hospital, Mt Claremont WA 6190, Australia.
* To whom correspondence should be addressed.
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Abstract |
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Regardless of a wide research interest the nature of a relationship between
cannabis use and schizophrenia is controversial. One of the physiological abnormalities
in schizophrenia is attention-modulated deficit in prepulse inhibition (PPI), which is a
normal reduction in the startle reflex magnitude when a non-startling stimulus
(prepulse) precedes the startling stimulus (pulse). This experiment was designed to
determine whether or not otherwise healthy people using cannabis would exhibit
attention-modulated deficit in PPI. The startle reflex was recorded in carefully
screened healthy humans attending to and ignoring auditory pulse and prepulse stimuli
separated by short (20-200 ms) and long prepulse intervals (1600 ms). In contrast to 12
non-using controls, cannabis use in 16 healthy humans was associated with significant
reduction in %PPI while attending to auditory stimuli, but not while ignoring them. The
PPI was correlated with the duration of cannabis use but not with the concentration of
cannabinoid metabolites in urine and the recency of cannabis use in the preceding 24
hours. Cannabis use was not associated with changes in prepulse facilitation of startle
reflex magnitude (%PPF) at long prepulse intervals, prepulse facilitation of startle
reflex latency and startle reflex magnitude in the absence of prepulses. These results
suggest that chronic, but not acute, use of cannabis is associated with
schizophrenia-like disruption in PPI in healthy controls. Such reduction in PPI is
attention-dependent and does not reflect a global deficit in sensorimotor gating in
cannabis users.
Key Words:
cannabis use, attention, prepulse inhibition, startle reflex, human
