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Tolerance and cross-tolerance to neurocognitive effects of THC and alcohol in heavy cannabis users.

Ramaekers JG, Theunissen EL, de Brouwer M, Toennes SW, Moeller MR, Kauert G - Psychopharmacology (Berl.) (2010)

Bottom Line: THC generally did not affect task performance.However, combined effects of THC and alcohol on divided attention were bigger than those by alcohol alone.In conclusion, the present study generally confirms that heavy cannabis users develop tolerance to the impairing effects of THC on neurocognitive task performance.

View Article: PubMed Central - PubMed

Affiliation: Department Neuropsychology and Psychopharmacology, Faculty of Psychology and Neuroscience, Maastricht University, Maastricht, The Netherlands. j.ramaekers@maastrichtuniversity.nl

ABSTRACT

Introduction: Previous research has shown that heavy cannabis users develop tolerance to the impairing effects of Δ9-tetrahydrocannabinol (THC) on neurocognitive functions. Animal studies suggest that chronic cannabis consumption may also produce cross-tolerance for the impairing effects of alcohol, but supportive data in humans is scarce.

Purpose: The present study was designed to assess tolerance and cross-tolerance to the neurocognitive effects of THC and alcohol in heavy cannabis users.

Methods: Twenty-one heavy cannabis users participated in a double-blind, placebo-controlled, three-way study. Subjects underwent three alcohol-dosing conditions that were designed to achieve a steady blood alcohol concentration of about 0, 0.5, and 0.7 mg/ml during a 5-h time window. In addition, subjects smoked a THC cigarette (400 μg/kg) at 3 h post-onset of alcohol dosing during every alcohol condition. Performance tests were conducted repeatedly between 0 and 7 h after onset of drinking and included measures of perceptual motor control (critical tracking task), dual task processing (divided-attention task), motor inhibition (stop-signal task), and cognition (Tower of London).

Results: Alcohol significantly impaired critical tracking, divided attention, and stop-signal performance. THC generally did not affect task performance. However, combined effects of THC and alcohol on divided attention were bigger than those by alcohol alone.

Conclusion: In conclusion, the present study generally confirms that heavy cannabis users develop tolerance to the impairing effects of THC on neurocognitive task performance. Yet, heavy cannabis users did not develop cross-tolerance to the impairing effects of alcohol, and the presence of the latter even selectively potentiated THC effects on measures of divided attention.

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Related in: MedlinePlus

Mean (SE) subjective high (lower panel) and drunkenness (middle panel) as a function of time after alcohol and THC administration. The upper panel displays subjective dominance of alcohol or THC over time
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Fig2: Mean (SE) subjective high (lower panel) and drunkenness (middle panel) as a function of time after alcohol and THC administration. The upper panel displays subjective dominance of alcohol or THC over time

Mentions: Subjective high was significantly elevated by the factor THC (F8,462 = 64.7; p = 0.000). Subjective drunkenness was significantly elevated by alcohol (F8,462 = 86.6; p = 0.000). Subjects indicated that the feeling of drunkenness was dominant prior to THC smoking and that the feeling of high was dominant after smoking. Mean (SE) rating of subjective high, drunkenness, and dominance of drug are shown in Fig. 2.Fig. 2


Tolerance and cross-tolerance to neurocognitive effects of THC and alcohol in heavy cannabis users.

Ramaekers JG, Theunissen EL, de Brouwer M, Toennes SW, Moeller MR, Kauert G - Psychopharmacology (Berl.) (2010)

Mean (SE) subjective high (lower panel) and drunkenness (middle panel) as a function of time after alcohol and THC administration. The upper panel displays subjective dominance of alcohol or THC over time
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC3045517&req=5

Fig2: Mean (SE) subjective high (lower panel) and drunkenness (middle panel) as a function of time after alcohol and THC administration. The upper panel displays subjective dominance of alcohol or THC over time
Mentions: Subjective high was significantly elevated by the factor THC (F8,462 = 64.7; p = 0.000). Subjective drunkenness was significantly elevated by alcohol (F8,462 = 86.6; p = 0.000). Subjects indicated that the feeling of drunkenness was dominant prior to THC smoking and that the feeling of high was dominant after smoking. Mean (SE) rating of subjective high, drunkenness, and dominance of drug are shown in Fig. 2.Fig. 2

Bottom Line: THC generally did not affect task performance.However, combined effects of THC and alcohol on divided attention were bigger than those by alcohol alone.In conclusion, the present study generally confirms that heavy cannabis users develop tolerance to the impairing effects of THC on neurocognitive task performance.

View Article: PubMed Central - PubMed

Affiliation: Department Neuropsychology and Psychopharmacology, Faculty of Psychology and Neuroscience, Maastricht University, Maastricht, The Netherlands. j.ramaekers@maastrichtuniversity.nl

ABSTRACT

Introduction: Previous research has shown that heavy cannabis users develop tolerance to the impairing effects of Δ9-tetrahydrocannabinol (THC) on neurocognitive functions. Animal studies suggest that chronic cannabis consumption may also produce cross-tolerance for the impairing effects of alcohol, but supportive data in humans is scarce.

Purpose: The present study was designed to assess tolerance and cross-tolerance to the neurocognitive effects of THC and alcohol in heavy cannabis users.

Methods: Twenty-one heavy cannabis users participated in a double-blind, placebo-controlled, three-way study. Subjects underwent three alcohol-dosing conditions that were designed to achieve a steady blood alcohol concentration of about 0, 0.5, and 0.7 mg/ml during a 5-h time window. In addition, subjects smoked a THC cigarette (400 μg/kg) at 3 h post-onset of alcohol dosing during every alcohol condition. Performance tests were conducted repeatedly between 0 and 7 h after onset of drinking and included measures of perceptual motor control (critical tracking task), dual task processing (divided-attention task), motor inhibition (stop-signal task), and cognition (Tower of London).

Results: Alcohol significantly impaired critical tracking, divided attention, and stop-signal performance. THC generally did not affect task performance. However, combined effects of THC and alcohol on divided attention were bigger than those by alcohol alone.

Conclusion: In conclusion, the present study generally confirms that heavy cannabis users develop tolerance to the impairing effects of THC on neurocognitive task performance. Yet, heavy cannabis users did not develop cross-tolerance to the impairing effects of alcohol, and the presence of the latter even selectively potentiated THC effects on measures of divided attention.

Show MeSH
Related in: MedlinePlus