Undetected neuropsychophysiological sequelae of khat chewing in standard aviation medical examination.

Background: Khat (Catha edulis Forsk) is a plant whose leaves contain cathinone, a natural amphetamine. Its leaves are chewed for their effect of central nervous system stimulation and sympathomimesis. Method: We examined 25 regular (daily) khat chewing flight attendants (RC), 39 social (occasional) khat-chewing flight attendants (SC), and 24 non-khat-chewing aircrew members (NC) who presented for FAA medical examinations, using electroencephalgraphic (EEG) frequency analysis and 4 psychometric tests measuring perceptual-visual memory and decision-speed. Results: Memory function test scores were significantly lower in khat chewers than NC's, and in RC's than SC's. They correlated significantly negatively with both duration and quantity of khat abuse in both khat-chewing groups. While EEG analysis revealed a statistically significant shift towards fast frequency bands in RC's compared to SC's or NC's, it did not significantly correlate with, or influence, any of the tested memory functions. Conclusion: The results suggest an adverse effect of khat chewing on perceptual-visual memory and decision-speed regardless of EEG frequency changes, and are discussed in relation to aviation safety and standard FAA Aviation Medical Examination.