Altered affective response in marijuana smokers: an FMRI study

Area of Science:

• Neuroscience
• Psychiatry

Background:

• Marijuana is the most widely used illicit drug in the U.S.
• Cognitive effects of marijuana include alterations in executive functions like decision-making.
• Endocannabinoids influence emotional responses, but smokers' reactions to affective stimuli are not well understood.

Purpose of the Study:

• To investigate functional magnetic resonance imaging (fMRI) patterns in chronic heavy marijuana smokers compared to non-smokers.
• To examine brain responses to masked emotional faces (happy and fearful).
• To test the hypothesis of altered fMRI activation in the anterior cingulate and amygdala.

Main Methods:

• Compared fMRI activation patterns in 15 chronic heavy marijuana smokers and 15 non-smoking controls.
• Subjects viewed masked happy and fearful faces.
• Activity in the anterior cingulate and amygdala was measured.

Main Results:

• Smokers showed decreased anterior cingulate and amygdalar activity during emotional stimuli.
• Controls exhibited increased activation in these regions.
• No significant clinical or demographic differences between groups.

Conclusions:

• Chronic heavy marijuana smoking is associated with altered frontal and limbic system activation.
• These findings suggest marijuana smokers process emotional information differently, even unconsciously.
• Altered affective processing may have negative consequences for marijuana users.