Mental Health in the Cree Peoples of Northern Quebec: Relationships Among Trauma, Familial Psychological Distress, and Mood or Anxiety Disorders.

OBJECTIVE: This study examined the physical and mental health of Cree adults, as well as the personal, clinical, and environmental factors associated with the presence of lifetime anxiety and mood disorders. METHODS: Mental health was assessed using the computerised version of the Diagnostic Interview Schedule (CDIS-IV), and standardised instruments were used to assess physical health, addiction severity, and psychological distress in 506 randomly selected participants from 4 Northern Cree communities in Quebec. RESULTS: Overall, 46.1% of participants reported chronic medical problems, 42.1% were current smokers and 34.5% met the DSM-IV criteria for an anxiety or mood disorder. Individuals with an anxiety or mood disorder were younger, predominantly female, and with higher educational levels, and a large proportion (47.7%) met the lifetime criteria for substance dependence. Hierarchical regression determined that anxiety or mood disorders were associated with serious problems getting along with parents, a history of physical and sexual abuse, and a lifetime diagnosis of substance dependence. Overall, 29.7% of Cree adults reported sexual abuse, 47.1% physical abuse, and 52.9% emotional abuse. CONCLUSIONS: This study highlights the high rates of physical and mental health problems in Cree communities and the association among parental history of psychological problems, history of abuse, and psychological distress. Participants expressed a desire for additional medical and psychological treatments to address the patterns of abuse, trauma, and mental disorders that are burdening the Cree communities in Northern Quebec.

Mental Health Among Help-Seeking Urban Women: The Relationships Between Adverse Childhood Experiences, Sexual Abuse, and Suicidality.

Adverse childhood experiences (ACEs) and adult mental health were explored in a sample of urban Aboriginal ( n = 83) and non-Aboriginal ( n = 89) women. Childhood sexual abuse (CSA) was associated with negative home environments, teenage pregnancy, lifetime suicide attempts, and treatment seeking. Aboriginal women with CSA witnessed higher levels of physical/sexual abuse of family members. The severity of current psychological distress was associated with a history of childhood neglect. The results indicate that CSA rarely occurs in isolation, and that multiple ACEs are strongly associated with suicide attempts and treatment seeking in adulthood. Future studies should focus on the role of CSA in suicidality, as well as familial, community, and cultural protective factors.

Substance Misuse Is Associated With Increased Psychiatric Severity Among Treatment-Seeking Individuals With Borderline Personality Disorder.

Despite high prevalence rates of concurrent borderline personality disorder (BPD) and substance use disorders (SUDs), little is known about the impact of substance misuse on the presentation of BPD. Sixty-five individuals with BPD were assessed at intake and at 3- and 6-month follow-up. Assessment included validated instruments such as the Addiction Severity Index and the Revised Symptom Checklist (SCL-90-R). Over half (58.5%) of individuals entering treatment were currently misusing substances. Substance misuse was associated with more legal and employment problems, greater mood disturbance, impulsivity, and psychiatric severity, including almost all SCL-90-R subscales. For the majority of patients (58%), there was little change in substance misuse post-treatment. The high prevalence of substance misuse and its association with psychiatric severity among individuals with BPD suggest that substance misuse should be a targeted behavior during treatment, and further specialized interventions are needed for individuals with comorbid BPD and SUD.

High Prevalence of Physical Pain Among Treatment-Seeking Individuals With Borderline Personality Disorder.

Research has demonstrated that about 30% of chronic pain patients suffer from borderline personality disorder (BPD), yet pain is not often discussed in research on the treatment of BPD. Sixty-five patients entering outpatient treatment for BPD were assessed at baseline for the prevalence of DSM-IV lifetime pain disorder, current medical problems, and the experience of current pain as measured by the McGill Pain Questionnaire. DSM-IV lifetime pain disorder diagnosis was present in 65% of patients. Current pain was experienced by 89% of participants, with intensity ranging from mild (19%) to excruciating (2%). Some individuals (21.5%) also reported experiencing daily medical problems in the past month prior to entering treatment. Physical pain is highly prevalent among treatment-seeking individuals with BPD. This pain phenomenon should be considered during treatment to help prevent a lifetime of functional impairment, including the possibility of abusing substances as a maladaptive coping mechanism.

A comparison of socioeconomic status and mental health among inner-city Aboriginal and non-Aboriginal women.

Aboriginal women in urban areas have been reported to experience high rates of poverty, homelessness, interpersonal violence, and health problems. However, there are few prior ethnocultural comparisons of urban women from similar socioeconomic backgrounds. The current study explored the mental and physical health of Aboriginal and non-Aboriginal women accessing social services agencies and shelters. Half of the sample (n=172) was Aboriginal (48.3%). The lifetime rate of physical abuse was significantly higher in Aboriginal women, and they were more likely to have been victims of violence or crime in the past year (A=50.6%, NA=35.6%, p<0.05). Rates of teenage pregnancy (<18 years of age) were significantly higher among Aboriginals (A=51.3%, NA=30.6%, p<0.05) and they reported more parental drug/alcohol problems (A=79.2%, NA=56.5%, p<0.05). Aboriginal women were also more likely to have previously received treatment for a drug or alcohol problem. There were no differences in self-reported physical health, medication use, hospitalisations, and current substance misuse. Irrespective of ethnicity, lifetime rates of anxiety, depression and suicide attempts were extremely high. Future research should explore the effects of individual resources (e.g. social support, family relations) and cultural beliefs on women's ability to cope with the stress of living with adverse events, particularly among low SES women with children.

The Social and Psychological Impacts of Gambling in the Cree Communities of Northern Québec.

A detailed survey of gambling, addiction and mental health was conducted with randomly selected respondents (n = 506) from four Cree communities of Northern Quebec. The study examined the current patterns of gambling in relation to demographic, social, and psychological factors. Instruments included the Canadian Problem Gambling Index, Addiction Severity Index, Beck Depression Inventory and the computerized Diagnostic Interview Schedule for psychiatric diagnoses. Overall, 69.2 % of the total sample participated in any gambling/gaming activities over the past year; 20.6 % of this group were classified as moderate/high risk gamblers, and 3.2 % were classified in the highest "problem gambling" category. Considering the entire sample, the overall prevalence of problem gambling was 2.2 %. Women were significantly more likely to play bingo (56.6 %) compared to men (35.1 %) and they played more frequently; 20.8 % of women versus 3.8 % of men played once/week or more often. Compared to the no/low risk gamblers, a greater proportion of moderate/high risk gamblers were cigarette smokers (44.8 vs. 56.3 %), they were more likely to meet DSM-IV diagnostic criteria for alcohol dependence (21.2 vs. 46.2 %), and they were more likely to report moderate to severe depressive symptoms in the past month. Risk factors for problem gambling included traumatic life events (physical and emotional abuse), anxiety and depression, as well as drug/alcohol abuse. The high rates of comorbidity between problem gambling, tobacco dependence, substance abuse and other psychological problems demonstrate that gambling among some Cree adults is part of a pattern of high-risk factors for negative long-term health consequences. The results also have implications for treatment, suggesting that interventions for gambling disorders should not focus on gambling alone but rather the constellation of high-risk behaviours that pose a risk to recovery and well-being.

Poorer Drinking Outcomes with Citalopram Treatment for Alcohol Dependence: A Randomized, Double-Blind, Placebo-Controlled Trial.

BACKGROUND: Previous research on the use of selective serotonin reuptake inhibitors (SSRIs) as a treatment for alcohol dependence has yielded mixed results. Depression has been shown to be a predictor of relapse and poor outcome following treatment, and it has been hypothesized that SSRIs would be beneficial in reducing drinking in depressed alcohol-dependent individuals. This randomized, double-blind, placebo-controlled trial was designed to test the effects of citalopram on treatment outcomes among alcohol-dependent individuals with and without depression. METHODS: Two hundred and sixty-five patients meeting criteria for a DSM-IV diagnosis of alcohol abuse or dependence were randomly assigned to receive placebo or citalopram 20 mg per day for the first week, followed by 40 mg per day from weeks 2 through 12. All patients received a standard course of treatment consisting of weekly individual and group psychotherapy. Participants were reassessed at 12 weeks, including dropouts from both treatment groups to determine rates of abstinence, changes in alcohol use, addiction severity, depressive symptoms, and psychiatric status. RESULTS: Citalopram provided no advantage over placebo in terms of treatment outcomes, and for some measures, citalopram produced poorer outcomes. Patients in the citalopram group had a higher number of heavy drinking days throughout the trial, and smaller changes in frequency and amount of alcohol consumption at 12 weeks. There was no influence of depression severity on outcomes in either medication group. Survival analyses also indicated no differences between depressed and nondepressed patients in the citalopram group for time to first slip or relapse. A diagnosis of personality disorder was associated with poorer treatment responses overall, regardless of treatment condition. CONCLUSIONS: This trial does not support the use of citalopram in the treatment of alcohol dependence. The results suggest that the use of SSRIs among depressed and nondepressed alcohol-dependent individuals early in recovery, prior to the onset of abstinence, may be contraindicated.

From policy to practice: implementing frontline community health services for substance dependence--study protocol.

BACKGROUND: Substance abuse is a worldwide public health concern. Extensive scientific research has shown that screening and brief interventions for substance use disorders administered in primary care provide substantial benefit at relatively low cost. Frontline health clinicians are well placed to detect and treat patients with substance use disorders. Despite effectiveness shown in research, there are many factors that impact the implementation of these practices in real-world clinical practice. Recently, the Ministry of Health and Social Services in Quebec, Canada, issued two policy documents aimed at introducing screening and early intervention for substance abuse into frontline healthcare clinics in Quebec. The current research protocol was developed in order to study the process of implementation of evidence-based addiction treatment practices at three primary care clinics in Montreal (Phase 1). In addition, the research protocol was designed to examine the efficacy of overall policy implementation, including barriers and facilitators to addictions program development throughout Quebec (Phase 2). METHODS/DESIGN: Phase 1 will provide an in-depth case study of knowledge translation and implementation. The study protocol will utilize an integrated knowledge translation strategy to build collaborative mechanisms for knowledge exchange between researchers, addiction specialists, and frontline practitioners (guided by the principles of participatory-action research), and directly examine the process of knowledge uptake and barriers to transfer using both qualitative and quantitative methodologies. Evaluation will involve multiple measures, time points and domains; program uptake and effectiveness will be determined by changes in healthcare service delivery, sustainability and outcomes. In Phase 2, qualitative methods will be utilized to examine the contextual facilitators and barriers that frontline organizations face in implementing services for substance dependence. Phase 2 will provide the first study exploring the wide-scale implementation of frontline services for substance dependence in the province of Quebec and yield needed information about how to effectively implement mandated policies into clinical practice and impact public health. DISCUSSION: Findings from this research program will contribute to the understanding of factors associated with implementation of frontline services for substance dependence and help to inform future policy and organizational support for the implementation of evidence-based practices.

Methods for intravenous self administration in a mouse model.

Animal models have been developed to study the reinforcing effects of drugs, including the intravenous self-administration (IVSA) paradigm. The advantages of using an IVSA paradigm to study the reinforcing properties of drugs of abuse such as cocaine include the fact that the drug is self-administered instead of experimenter-administered, the schedule of reinforcement can be altered, and accurate measurement of the quantities of drug consumed as well as the timing and pattern of IV injections can be obtained. Furthermore, the intravenous route of administration avoids potential confounds related to first pass metabolism or taste, and produces rapid increases in blood and brain drug levels. As outlined in this video, intravenous self-administration can be obtained without prior food restriction or prior drug training following careful catheter placement during surgery and meticulous daily catheter flushing and maintenance. Experimental procedures outlined in this paper include a description of animal housing and acclimation methods, operant training using sweetened milk solutions, and catheter implantation surgery.

Personality disorders among alcoholic outpatients: prevalence and course in treatment.

OBJECTIVE: To determine the prevalence of concurrent personality disorders (PDs) among alcoholic men and women seeking outpatient treatment, and to examine their effect on the course of alcohol treatment. METHOD: Patients with alcohol use disorders (n = 165) were assessed by clinical and semi-structured interviews, as well as self-report scales, to measure levels of psychological distress, impulsivity, social functioning, and addiction severity at treatment intake. PD diagnoses were assessed using the Structured Clinical Interview for Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition, Personality Disorder (SCID-II). Course in treatment was monitored prospectively for 12 weeks. RESULTS: Using the results of the SCID-II (n = 138), the sample was divided into 3 groups-that is, no PD 41% (n = 57), Cluster B PD 32% (n = 44), and other PD 27% (n = 37). The 3 groups did not differ in their alcohol use severity at intake. However, the Cluster B PD group achieved alcohol milestones at a younger age. Subjects with a PD had more severe psychological and social problems at intake. The Cluster B PD group showed significantly higher levels of impulsivity at intake, greater likelihood of early treatment dropout, and quicker times to first slip and to relapse. CONCLUSIONS: This study supports the high prevalence of concurrent PDs, particularly Cluster B PDs, among treatment-seeking alcoholics. The relation between observed high levels of impulsivity and worse course in early alcohol treatment among people with a Cluster B PD merits further investigation.

Early recovery from alcohol dependence: factors that promote or impede abstinence.

The objectives of this prospective follow-up study were to identify factors that promote or impede the early recovery process and to examine whether drinking status at 4 weeks predicts later abstinence. Patients with alcohol use disorders were assessed by clinical and semistructured interviews upon entering addiction treatment (N = 175) and were followed up biweekly to monitor their alcohol use. During the first 4 weeks of treatment, 57% (n = 100) of patients slipped or relapsed on alcohol, whereas 43% (n = 75) were fully abstinent. Patients who slipped or relapsed were more likely to report nondependent use of a secondary substance, meet criteria for a Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition Axis II Cluster B personality disorder, have a higher level of impulsivity, and have more severe social problems at intake. The final logistic regression model accounted for 37% of the variance in drinking status. Patients who slipped or relapsed early in treatment were likely to continue to struggle to maintain abstinence at 12 weeks.

A verification of previously identified QTLs for cocaine-induced activation using a panel of B6.A chromosome substitution strains (CSS) and A/J x C57Bl/6J F2 mice.

BACKGROUND: The objective of this study was to confirm provisional quantitative trait loci (QTL) for cocaine-induced locomotor activation, on chromosomes 1, 5, 6, 9, 12, 15, 16, 17, and 18, previously identified in the AXB/BXA recombinant inbred (RI) and AcB/BcA recombinant congenic (RC) strains of mice derived from A/J (A) and C57BL/6J (B6) progenitors. This was accomplished through a genetic analysis of cocaine-induced activity in an AxB6 F2 cross and a phenotypic survey across a panel of B6.A chromosome substitution strains (CSS) mice. Mice were tested for cocaine-induced activity, following administration of saline and cocaine (20 mg/kg), utilizing an open-field procedure. RESULTS: Among AxB6 F2 mice, differences in cocaine-induced activity were associated with loci on chromosome 1 (D1Mit305), 5 (D5Mit409), 16 (D16Mit131), and 18 (D18Mit189). A survey of the CSS panel confirmed cocaine QTLs on chromosomes 5 and 15, previously identified in RI or RC strains. Overall, the regions on chromosomes 5 and 18 represent verification of QTL previously identified in both the RC and RI strains. Additionally, the B6 allele for these QTL was consistently associated with greater relative cocaine activation. CONCLUSIONS: Collectively, chromosome 5 and 18 QTL have now been replicated in multiple independent crosses derived from the A/J and C57BL/6J progenitors. The use of an in silico analysis highlighted potential candidate genes on chromosomes 5 and 18. The present results complement the targeted gene approach currently prevalent in the study of cocaine and provide a broader empirically based focus for subsequent candidate gene studies.

Genetic analysis of the psychostimulant effects of nicotine in chromosome substitution strains and F2 crosses derived from A/J and C57BL/6J progenitors.

Previous research utilizing the AcB/BcA recombinant congenic strains (RCS) of mice mapped provisional quantitative trait loci (QTLs) for the psychostimulant effects of nicotine to multiple regions on chromosomes 7, 11, 12, 14, 16, and 17. The current study was designed to confirm these QTLs in an A/J (A) x C57Bl/6J (B6) F2 cross and a panel of B6.A chromosome substitution strains (CSS). The panel of B6.A CSS consists of 21 strains, each carrying a different A/J chromosome on a B6 background. The A x B6 F2, CSS, A, and B6 mice were tested for sensitivity to the effects of nicotine on locomotor activity using a computerized open-field apparatus. In A x B6 F2 mice two QTLs were identified which confirm those previously observed in the AcB/BcA RCS. Significant differences in the expression of nicotine-induced activity were associated with loci on chromosome 11 (D11Mit62) and chromosome 16 (D16Mit131) in the A x B6 F2. At the chromosome 11 QTL, an A allele was associated with lower nicotine-induced activity scores relative to the B6. In contrast, the A allele was associated with greater relative nicotine activity values for the chromosome 16 QTL. A survey of the CSS panel confirmed the presence of QTLs for nicotine activation on chromosomes 2, 14, 16, and 17 previously identified in the AcB/BcA RCS. In the informative CSS strains, A alleles were consistently associated with greater nicotine-induced activity scores compared to the B6. The results of the present study are the first to validate QTLs for sensitivity to the effects of nicotine across multiple strains of mice. QTLs on chromosomes 2, 11, 14, 16, and 17 were confirmed in CSS and/or F2 mice. Significantly, the identification of a QTL on chromosome 16 has now been replicated in three crosses derived from the A and B6 progenitors.

Confirmation of provisional quantitative trait loci for voluntary alcohol consumption: genetic analysis in chromosome substitution strains and F2 crosses derived from A/J and C57BL/6J progenitors.

AIMS: Earlier research utilizing AXB/BXA recombinant inbred (RI) and AcB/BcA recombinant congenic (RC) strains of mice independently mapped provisional quantitative trait loci (QTL) for voluntary alcohol consumption (VAC) to common chromosomal regions. This study was designed to confirm QTL on chromosomes 2, 3, 5, 7, and 15 in an A/J (A)xC57Bl/6J (B6) F2 cross, and a panel of B6.A chromosome substitution strains (CSS). METHODS AND RESULTS: AxB6F2 mice, CSS, and A/J and C57BL/6J progenitors were tested for VAC. Previously identified QTL regions were targeted for genotyping in the AxB6F2 mice. Among the AxB6F2 mice, significant differences in VAC were associated with loci on chromosome 2 (peak marker D2Mit367) and chromosome 3 (D3Mit189). Additionally, a significant interaction was observed between loci on chromosome 15 (D15Mit245) and chromosome 2 (D2Mit367). A survey of the CSS panel provided further evidence for VAC QTLs on chromosomes 2 and 15. In the CSS panel, lower ethanol consumption was observed in those strains carrying the A/J 2 or 15 chromosome on a B6 background. This finding is consistent with the allelic influences observed in AxB6F2 mice in this study and those reported previously in the RI and RC strains of mice. Specifically, A/J alleles were associated with decreased ethanol consumption whereas C57BL/6J alleles were associated with increased ethanol consumption. CONCLUSION: The present results confirm previously reported QTL, on chromosomes 2 and 15 for VAC in RI and RC strains. Collectively, the regions on chromosomes 2 and 15 have now been replicated in at least three independent crosses derived from the A/J and C57BL/6J progenitors. The identification of potential candidate genes for the chromosome 15 QTL is discussed in the context of an in-silico analysis.

Sexual abuse and the outcome of addiction treatment.

The objective of this prospective follow-up study was to examine the effects of sexual abuse on substance use disorder patients' clinical presentation and course in treatment. Consecutive admissions to the MUHC's Addictions Unit were assessed at intake (N=206) and six-month follow-up (n=172). Assessments evaluated socio-demographic and psychiatric characteristics, addiction severity, and physical and/or sexual abuse histories. Upon entering treatment, 23% reported prior sexual abuse with or without physical abuse. Patients with a sexual abuse history had higher rates of psychological problems, stronger family histories of substance use disorders, and more impaired family relationships. At six months, there were no differences between patients with and without sexual abuse histories in their response to treatment, or their utilization of treatment services. The current study failed to show that prior sexual abuse compromised short-term treatment outcomes.

Association between concurrent depression and anxiety and six-month outcome of addiction treatment.

OBJECTIVES: This six-month prospective study of 326 patients with substance use disorders assessed rates of depression and anxiety symptoms among patients entering addiction treatment and examined the effects of concurrent psychiatric symptoms on indicators of addiction treatment outcome. METHODS: Initial assessments included semistructured clinical interviews, the Addiction Severity Index (ASI), the Beck Depression Inventory (BDI), and the Symptom Checklist 90-Revised (SCL90-R). Patients were reassessed at six months to determine treatment outcome (abstinence status and duration of continuous abstinence). RESULTS: A majority of the sample (63 percent) had significant psychiatric symptoms at intake: 15 percent (N=49) presented with depressive symptoms, 16 percent (N=53) with anxiety symptoms, and 32 percent (N=105) with combined depressive and anxiety symptoms. Forty percent of patients who presented with combined depression and anxiety symptoms were abstinent at six months. These patients fared worse than those who were less symptomatic at intake, including those who presented with depression symptoms alone; in the latter group, 73 percent were abstinent at six months. The hierarchical regression models accounted for 22 percent of the variance in the duration of continuous abstinence, 26 percent of the variance in the frequency of drug use at six months, and 39 percent of the variance in abstinence status at six months. Key predictor variables included days in treatment, primary drug of abuse, frequency of drug use, and report of concurrent depression or anxiety symptoms at intake. CONCLUSIONS: Concurrent depression or anxiety symptoms at intake had a small but significant predictive effect on addiction treatment outcome over and above factors that are clearly known to influence outcome (length of stay in treatment and initial addiction severity).

Quantitative trait loci for novelty/stress-induced locomotor activation in recombinant inbred (RI) and recombinant congenic (RC) strains of mice.

The objective of the present study was to map and compare quantitative trait loci (QTLs) for an anxiety-related trait (novelty/stress-induced activation) in the AXB/BXA recombinant inbred (RI) and AcB/BcA recombinant congenic (RC) strains of mice derived from the A/J and C57BL/6J inbred progenitor strains. Activational responses to a novel open field (OF) were measured under identical stressful conditions (no prior handling or exposure to testing procedures) in both the RI and RC strains. Naive male and female mice were weighed, injected with IP saline and locomotor activity was monitored in a computerized OF apparatus for 15 min. Measures obtained from this experimental design included: (1) total activity scores, (2) time course of response (5 min time blocks over the 15 min session). Data for the RI strains were subjected to a QTL analysis using composite interval mapping. Significant loci were identified on chr 5 (D5Mit356, 41 cM), chr 8 (D8Mit305, 37 cM) and chr 14 (D14Mit36, 6 3cM). Single locus association analysis of the AcB/BcA RC strains identified 15 putative regions, 7 of which overlapped regions independently mapped in the RI strains on chr 1 (58.5-63.1cM), chr 4 (21.9-28.6 cM), chr 5 (19-45 & 74-86 cM), chr 6 (0.5-20.4cM), chr 9 (15-38 cM), chr 13 (47cM) and chr 19 (47cM). The loci identified on chr 5 near D5Mit356 (41cM) in both the AXB/BXA RIS and AcB/BcA RCS maps to a region containing the genes for several GABA(A) receptor subunits. Additionally, the present study provides further confirmation of a frequently identified QTL on chromosome 1. The results are discussed in the context of previous QTL studies of anxiety-related traits that have used genetic crosses that include the A or B6 progenitors.

Confirmation of quantitative trait loci for cocaine-induced activation in the AcB/BcA series of recombinant congenic strains.

Individual differences in the psychomotor stimulant effects of cocaine are influenced by genetic factors. Several quantitative trait loci (QTL) have been identified for cocaine-induced locomotor activation using the AXB/BXA recombinant inbred series of strains derived from the A/J (A) and C57BL/6J (B6). The aim of the present study was to conduct an independent analysis of cocaine-induced activation in the AcB/BcA recombinant congenic strains. The AcB/BcA RC series consists of 37 inbred strains derived from reciprocal backcrosses between the A and B6, followed by systematic inbreeding. Locomotor activity was measured in a computerized open-field apparatus following intraperitoneal administration of saline and cocaine (20 mg/kg). Linkage maps constructed with 625 informative microsatellite markers were used to identify chromosomal regions associated with cocaine difference scores. Significant (P < 0.00001) regions were identified on chromosomes 1 (13-25.7 and 36.9-58.5 cM), 5 (1-28 and 84-86 cM), 6 (7-26.35 cM), 7 (9.4-27.8 cM), 9 (9-28 cM), 13 (21-37 cM), 16 (36-66 cM), 17 (22.5-24.5 cM) and 18 (45-48 cM). Multiple regression analysis demonstrated that a subset of four markers, including D5Mit182 (24 cM), D5Mit409 (84 cM), D7Mit83 (26.5 cM) and D13Mit54 (35 cM), accounted for 90% of the genetic variance in cocaine difference scores. The results of the present study provide confirmation for a number of QTL on chromosomes 1, 5, 6, 9, 16 and 17 which were previously identified in the recombinant inbred AXB/BXA and BXD strains that share a common B6 ancestor.