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Changes in middle cerebral artery velocity after marijuana
R J Mathew1, W H Wilson, D F Humphreys
1Department of Psychiatry, Duke University Medical Center, Durham, North Carolina 27710.
Biological Psychiatry
|July 15, 1992
Summary
Smoking marijuana significantly increases blood flow velocity in the middle cerebral artery (MCA). This effect on MCA velocity differs from its impact on pulse rate, with no significant changes in blood pressure or carbon dioxide levels observed.
Area of Science:
- Neuroscience
- Cardiovascular Physiology
- Pharmacology
Background:
- Understanding the physiological effects of marijuana is crucial.
- Cerebral blood flow regulation is vital for brain health.
- Previous research has yielded mixed results on marijuana's cardiovascular and cerebrovascular impacts.
Purpose of the Study:
- To investigate the acute effects of marijuana smoking on middle cerebral artery (MCA) blood flow velocity.
- To compare the time course of changes in MCA velocity with pulse rate following marijuana consumption.
- To assess the impact of marijuana on blood pressure and end-tidal carbon dioxide levels.
Main Methods:
- Healthy male volunteers (n=10) with prior marijuana use history participated.
- Transcranial Doppler (TCD) was used to measure MCA blood flow velocity.
- Measurements were taken before, during, and 1 hour after smoking a marijuana or placebo cigarette.
Main Results:
- Marijuana smoking led to a significant increase in MCA blood flow velocity.
- Pulse rate also increased post-marijuana, but its time course differed from MCA velocity changes.
- No significant alterations in blood pressure or end-tidal carbon dioxide were detected.
Conclusions:
- Acute marijuana smoking elevates cerebral blood flow velocity in the MCA.
- The cerebrovascular response to marijuana differs from its effect on heart rate.
- Marijuana does not appear to significantly affect blood pressure or ventilation in the short term.