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The acute effects of tetrahydrocannabinol on auditory threshold and frequency resolution in human subjects
M Mulheran1, P Middleton, J A Henry
1MRC Toxicology Unit, University of Leicester, Hodgkin Building, Lancaster Road, Leicester LE1 9HN, UK. mm22@le.ac.uk
Aims:
The study was designed to investigate the acute effects of ingested tetrahydrocannabinol (THC) on auditory function.
Methods:
Eight male subjects (aged 22-30 years), who had previous experience of cannabis use, took part in this study. They performed air conduction pure tone audiometry in both ears over 0.5-8 kHz. A simple test of frequency selectivity by detecting a 4-kHz tone under two masking noise conditions was also carried out in one ear. Three test sessions at weekly intervals were carried out, at the start of which they ingested a capsule containing either placebo, or 7.5 or 15 mg of THC. These were administered in a randomized cross-over, double-blind manner. Auditory testing as described above was carried out 2 hours after ingestion. Blood samples were also obtained at this time point and assayed for delta 9- and 11-OH-THC levels.
Results:
No significant changes in threshold or frequency resolution were seen with the dosages employed in this study.
Conclusions:
This suggests that THC at the plasma levels attained in this study does not have profound effect on the processing of elementary stimuli by the auditory pathway.