Superior efficacy of cognitive-behavioral therapy for urban crack cocaine abusers: main and matching effects.

This study evaluated the efficacy of cognitive-behavioral therapy (CBT) and 12-step facilitation (12SF) in treating cocaine abuse. Participants (N = 128) were randomly assigned to treatment conditions and assessed at baseline and at Weeks 4, 8, 12, and 26. Treatment lasted for 12 weeks. It was hypothesized that participants treated with CBT would be significantly more likely to achieve abstinence from cocaine than participants treated with 12SF. A series of patient-treatment matching hypotheses was also proposed. Across 2 different outcome variables, it was found that participants in CBT were significantly more likely to achieve abstinence than participants in 12SF. In addition, some support for matching hypotheses was found, suggesting that both psychotherapies may be differentially effective for identified subgroups of persons that abuse cocaine.

Effect of interdose interval on the development of associative tolerance to morphine in the rat: a dose-response analysis.

Three experiments examined the effect of interdose interval (IDI) on the development and retention of associative tolerance to the analgesic effects of morphine. Tolerance was indexed as the magnitude of the shift to the right of the dose-response curve (DRC). Experiment 1 showed that associative tolerance was characterized by a parallel shift in the DRC to the right in rats that had received morphine explicitly paired with the distinctive test context at 12-, 24-, and 96-hr IDIs. Associative tolerance was attenuated at the shortest IDI. Experiment 2 revealed that associative tolerance that developed in the 12- and 96-hr IDI conditions showed comparable levels of retention at 30 days. Experiment 3 showed that associative tolerance was not disrupted by the administration of unsignaled doses of morphine 12 hr before each drug-context pairing. Theoretical and methodological implications of the data are discussed.

Associative morphine tolerance in the rat: examinations of compensatory responding and cross-tolerance with stress-induced analgesia.

The results of three experiments designed to examine the processes subserving associative tolerance to morphine's analgesic effects, as assessed by the tail-flick test, are reported. The experiments indicated that associative tolerance in male Holtzman rats was not subserved by conditioned compensatory responses but was cross-tolerant with an apparently nonopioid form of stress-induced analgesia (SIA). Experiment 1 showed that rats tested for morphine analgesia in a distinctive context that had been paired previously with morphine injections (5 mg/kg) were more tolerant than animals that had had this context explicitly unpaired with a series of morphine injections or animals that were drug-naive. There was no evidence of a conditioned compensatory response of hyperalgesia in animals given a saline injection in the presence of environmental stimuli that had been previously paired with morphine, even under test conditions designed to minimize the possibility of floor effects that might have obscured the detection of drug-compensatory hyperalgesia. Experiment 2 demonstrated that the footshock procedures used for stress induction produced an SIA that was not attenuated by naloxone (10 mg/kg). Experiment 3 replicated the associative tolerance phenomenon of Experiment 1 and again failed to find evidence of conditioned compensatory responses. It was found that animals exposed to footshock in the context that had been associated with morphine administration developed significantly less SIA than control animals. The relevance of these findings for associative models of drug tolerance is discussed.

Tolerance to morphine in the rat: associative and nonassociative effects.

Two experiments were conducted to examine the impact of dose level and interdose interval (IDI) on the development of tolerance to the analgesic effect of morphine. In Experiment 1, rats were administered a series of low- (5 mg/kg) or high- (30 mg/kg) dose injections of morphine either explicitly paired or unpaired with a distinctive context at a 48-hr IDI. The development of tolerance following this regimen was assessed by shifts in dose-response curves to the right when animals were tested on a tail-flick device in the distinctive context. Only animals that had received morphine paired with the distinctive context were tolerant to morphine; the magnitude of this associative tolerance was a positive function of the level of the conditioning dose. In Experiment 2, rats were exposed to a high dose of morphine (30 mg/kg) either paired or unpaired with a distinctive context at one of two IDIs (24 or 96 hr). Tolerance testing revealed that at the long IDI, only associative tolerance was evident, whereas at the short IDI, tolerance in the unpaired condition was more pronounced with a corresponding decline in the development of associative tolerance. The relevance of these findings for psychological theories of drug tolerance are discussed. The overall pattern of results are consistent with the predictions of an habituation model of drug tolerance.

The contribution of classical conditioning to tolerance to the antinociceptive effects of ethanol.

In rats, ethanol increases the latency of the tail-flick reflex to radiant heat. Three experiments examined the contribution of classical conditioning to the acquisition of tolerance to this antinociception. Experiment 1 showed that the antinociception produced by ethanol was dose dependent. The results of Experiment 2 demonstrated that rats exposed to a series of ethanol injections paired with a distinctive environment developed tolerance to this antinociception. In Experiment 3, tolerance was more pronounced in animals that had been exposed to ethanol and tested in the distinctive environment than in animals that had received ethanol in a nondistinctive environment. In contrast to previous reports in the literature, these results show that animals need not practice the tail-flick reflex while intoxicated in order to develop tolerance. Additionally, the data suggest that classical conditioning may contribute to tolerance to the antinociceptive effects of ethanol.