MARIJUANA really does give you a headrush. In frequent cannabis users, blood flows faster through the arteries of the brain than in people who do not use the drug.
According to Jean Cadet of the National Institute on Drug Abuse in Baltimore, Maryland, the faster flow may be an attempt to compensate for a lack of oxygen in the brain caused by cannabis. He claims his findings could explain why the drug affects short-term memory.
Cadet measured blood flow in the brains of 54 frequent marijuana smokers using a method called transcranial Doppler sonography. Even in the group he describes as 鈥渓ight鈥� users, who smoked 11 joints a week on average, there was a clear difference in blood flow compared with 18 controls. An earlier study showed tobacco smokers have normal blood flow.
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After a month of observed non-smoking in a clinic, there was no improvement in people who smoked more than 78 joints a week on average. In those who had smoked fewer, blood flow fell slightly (Neurology, vol 64, p 488).
The findings may not apply to people who take marijuana in forms developed for medicinal purposes or who smoke it only occasionally, points out William Notcutt of James Paget Hospital in Great Yarmouth in the UK. Unlike frequent cannabis smokers, they are not exposed to large doses of the various toxic substances found in the smoke from joints, he points out.
