Liking THC Did Not Consistently Predict Liking Alcohol or Amphetamine in a Small Trial
A small controlled study did not support a simple tendency for the same people to enjoy every tested drug. Individual responses to THC, alcohol and amphetamine were largely unrelated.
Separate exposures, not a drug combination
Twenty-four healthy light drug users attended six sessions covering each active drug and its placebo comparison. Active conditions involved oral THC, alcohol or d-amphetamine separately. This was not a study of the drugs taken together or a test of cross-tolerance.
Group effects did not establish individual correlations
Each drug produced subjective effects at the group level. That does not mean the participants with the strongest response to one drug had the strongest response to another. Several specific associations were marginal or appeared only in small subgroups.
A subgroup result needs its direct comparison
A positive alcohol–amphetamine association appeared among participants reporting alcohol stimulation. However, the correlations in stimulant and sedative responders were not significantly different when directly compared. Significant within one subgroup and nonsignificant within another did not establish a confirmed difference between them.
Why this remains preliminary
The study used one dose of each drug, subjective intensities differed, blinding was imperfect and the sample was small and self-selected. Oral THC also differs from smoked cannabis. These findings do not predict an individual’s addiction risk or show how that person would respond to combined substances. They support caution about inferring a broad drug-response personality from one preferred substance.
Related analysis: evaluating cannabis tolerance claims.
Primary research
Wardle MC; Marcus BA; de Wit H. A Preliminary Investigation of Individual Differences in Subjective Responses to D-Amphetamine, Alcohol, and Delta-9-Tetrahydrocannabinol Using a Within-Subjects Randomized Trial. PloS one (2015). DOI: 10.1371/journal.pone.0140501.
