clearly include irritability. Third, we did not have precise measures of the amount of Δ9-THC ingested and cannabis potency and efficiency of smoked self-administration can vary considerably. Most of those in our sample appear to have been heavily exposed to cannabis during their period of heaviest use, but we cannot precisely quantify the relationship of cannabis ingested with the emergence of withdrawal symptoms on abstinence. Fourth, information is lacking on whether those in the sample who used cannabis 3–4 times a week used cannabis on consecutive days. However, these respondents constituted a minority of the sample, and results of the factor analysis were virtually identical when the 3–4x/week users were removed from the sample. Fifth, it is possible that individual symptoms we identified might be related to other conditions, e.g., that the individual symptom of weakness might reflect postural hypertension, a direct effect of cannabis use. 45 However, our wording of the question on the timing of the symptoms relative to cannabis use (“the morning after, or in the first few days after”) in addition to the empirical clustering of symptoms found reduces the possibility that the full syndrome reported is a conglomeration of individual symptoms resulting from other diverse
