Can "pure" implicit memory be isolated? A test of a single-system model of recognition and repetition priming.

Implicit memory is widely regarded as an unconscious form of memory. However, evidence for what is arguably a defining characteristic of implicit memory-that its contents are not accessible to awareness-has remained elusive. Such a finding of "pure" implicit memory would constitute evidence against a single-system model of recognition and priming that predicts that priming will not occur in the (true) absence of recognition. In three experiments, using a rapid serial visual presentation procedure at encoding, we tested this prediction by attempting to replicate some previous studies that claimed to obtain pure implicit memory. We found no evidence of priming in the absence of recognition; instead, priming and recognition were associated across experiments: when priming was absent, recognition was also absent (Experiments 1 and 2), and when priming was reliably greater than chance, recognition was similarly greater than chance (Experiment 3). The results are consistent with the prediction of a single-system model, which was fit to the data from all the experiments. The results are also consistent with the notion that the memory driving priming is accessible to awareness.

Changing patterns in opioid addiction: characterizing users of oxycodone and other opioids.

OBJECTIVE: To evaluate the clinical observation that the number of individuals seeking opioid detoxification from oxycodone was increasing at the Centre for Addiction and Mental Health (CAMH) in Toronto, Ont; and to identify the characteristics of individuals seeking opioid detoxification at CAMH. DESIGN: Retrospective analysis of patient health records. SETTING: Medical Withdrawal Management Service at CAMH. PARTICIPANTS: All patients admitted for opioid detoxification between January 2000 and December 2004. MAIN OUTCOME MEASURES: Number of opioid detoxification admissions each year; type, dose, and source of opioids; comorbid problems and symptoms. RESULTS: There were 571 opioid detoxification admissions during the 5-year study period. The number of admissions increased steadily over the 5 years; in particular, the number of admissions related to controlled-release oxycodone increased substantially (3.8%, 8.3%, 20.8%, 30.6%, and 55.4% of the total opioid admissions in 2000 to 2004, respectively; chi(4)2= 105.5, P < .001). The rates of admissions involving heroin remained low and stable. Use of controlled-release oxycodone was associated with considerably higher doses than use of other prescription opioids was. Physician prescriptions were the source of the prescription opioids for a large percentage of patients, particularly for older patients. Prescription opioid users reported considerable comorbid substance use problems, pain, and psychiatric symptoms. CONCLUSION: This study has demonstrated a significant rise in the number of individuals seeking treatment at CAMH for controlled-release oxycodone addiction. The substantial comorbid pain, psychiatric symptoms, and other psychoactive substance use problems in these patients, coupled with the finding that prescriptions were an important source of opioids, highlight the clinical complexities encountered in the treatment of these individuals. Further research examining these complexities and the many possible pathways leading to prescription opioid addiction is required in order to develop effective prevention and treatment strategies.

The impact of benzodiazepine use on methadone maintenance treatment outcomes.

The purposes of this study were to examine predictors of benzodiazepine use among methadone maintenance treatment patients, to determine whether baseline benzodiazepine use influenced ongoing use during methadone maintenance treatment, and to assess the effect of ongoing benzodiazepine use on treatment outcomes (i.e., opioid and cocaine use and treatment retention). A retrospective chart review of 172 methadone maintenance treatment patients (mean age = 34.6 years; standard deviation = 8.5 years; 64% male) from January 1997 to December 1999 was conducted. At baseline, 29% were "non-users" (past year) of benzodiazepine, 36% were "occasional users," and 35% were "regular/problem users." Regular/problem users were more likely to have started opioid use with prescription opioids, experienced more overdoses, and reported psychiatric comorbidity. Being female, more years of opioid use, and a history of psychiatric treatment were significant predictors of baseline benzodiazepine use. Ongoing benzodiazepine users were more likely to have opioid-positive and cocaine-positive urine screens during methadone maintenance treatment. Only ongoing cocaine use was negatively related to retention. Benzodiazepine use by methadone maintenance treatment patients is associated with a more complex clinical picture and may negatively influence treatment outcomes.

Brief treatment for young substance abusers: a pilot study in an addiction treatment setting.

The present study evaluated a motivationally based, 4-session outpatient intervention for young substance abusers presenting for addiction treatment. Follow-up interviews were conducted 6 months after assessment on (a) clients who sought additional help (n = 22) and (b) clients who did not seek additional help (n = 28). Results indicated that (a) participating in an assessment and brief intervention was associated with reduced use and consequences and increased confidence in high-risk situations up to 6 months after entry into the program, and (b) clients who participated in additional treatment showed less of a decrease in substance-related consequences. These findings suggest that brief interventions can serve as either a stand-alone intervention for individuals who need short-term assistance or a first-step intervention for those with more specialized or long-term needs.