Mental health and sociodemographic characteristics among Icelanders, data from a cross-sectional study in Iceland.

BACKGROUND: Mental health challenges are on the rise worldwide. In Iceland, little is known about the sociodemographic factors associated with poor mental health. This study aimed to investigate symptoms of depression, anxiety, stress, and psychiatric medication for mental disorders in a nationally representative sample in Iceland and to explore its associations with sociodemographic factors. METHODS: This Icelandic cross-sectional study 'Health and Wellbeing of Icelanders' was conducted in 2017 and included 9,887 randomly chosen adults. Participants' depression, anxiety, and stress levels were measured with the Depression Anxiety and Stress scale-21(DASS-21) and the association with sociodemographic factors and prescribed psychiatric medication was assessed in a multinominal logistic regression analysis. RESULTS: The youngest age group (18 to 29 years old) had the poorest mental health. Males had a higher risk of medium and high depression scores than females, RRR 1.23 (95% CI 1.06-1.44) and RRR 1.71 (95% CI 1.25-2.33) when adjusted for sociodemographic factors (age, sex, education, marital status, financial status, living area, employment) and use of psychiatric medication. Participants with the most considerable financial difficulties had the highest risk of high scores on depression RRR 11.19 (95% CI 5.8-21.57), anxiety RRR 12.35 (95% CI 5.62-27.14) and stress RRR 11.55 (95% CI 4.75-28.04) when compared to those that do not. CONCLUSIONS: The youngest participants and those with the most extensive financial difficulties had the highest depression, anxiety, and stress scores. Males scored higher than females on depression. There was a trend towards worse mental health with lower sociodemographic status. Higher education, living with someone, and financial security were associated with better mental health. These results implicate the importance of government actions to counteract social inequalities in the Icelandic nation.

High Rate of Hepatitis C Virus Reinfection Among Recently Injecting Drug Users: Results From the TraP Hep C Program-A Prospective Nationwide, Population-Based Study.

BACKGROUND: The Treatment as Prevention for Hepatitis C program started in 2016 in Iceland, offering treatment with direct-acting antivirals to hepatitis C virus (HCV)-infected individuals. Reinfections through injection drug use (IDU) can hamper elimination efforts. We determined reinfection rates of HCV among patients in the program. METHODS: Clinical data were gathered prospectively. The study cohort consisted of HCV-cured patients with an estimated sustained virologic response between 1 February 2016 and 20 November 2018, with follow-up until 20 November 2019. The observation period and time until reinfection was estimated using a single random point imputation method coupled with Monte Carlo simulation. The reinfection rates were expressed as reinfections per 100 person-years (PY). RESULTS: In total, 640 treatments of 614 patients (417 male; mean age, 44.3 years) resulted in cure, with 52 reinfections subsequently confirmed in 50 patients (37 male). Follow-up was 672.1 PY, with a median time to reinfection of 232 days. History of IDU was reported by 523 patients (84.8%) and recent IDU with 220 treatments (34.4%). Stimulants were the preferred injected drug in 85.5% of patients with a history of IDU. The reinfection rate was 7.7/100 PY. Using multivariate Cox proportional hazards models for interval-censored data, age (hazard ratio, 0.96 [95% confidence interval, .94-.99]) and recent IDU (2.91 [1.48-5.76]) were significantly associated with reinfection risk. CONCLUSIONS: The reinfection rate is high in a setting of widespread stimulant use, particularly in young people with recent IDU. Regular follow-up is important among high-risk populations to diagnose reinfections early and reduce transmission. CLINICAL TRIALS REGISTRATION: NCT02647879.

Cascade of care during the first 36 months of the treatment as prevention for hepatitis C (TraP HepC) programme in Iceland: a population-based study.

BACKGROUND: WHO has set targets to eliminate hepatitis C virus (HCV) infection as a global health threat by 2030 through a 65% reduction in HCV-related deaths and 80% reduction in HCV incidence. To achieve these goals, WHO set service coverage targets of 90% of the infected population being diagnosed and 80% of eligible patients being treated. In February, 2016, Iceland initiated a nationwide HCV elimination programme known as treatment as prevention for hepatitis C (TraP HepC), which aimed to maximise diagnosis and treatment access. This analysis reports on the HCV cascade of care in the first 3 years of the programme. METHODS: This population-based study was done between Feb 10, 2016, and Feb 10, 2019. Participants aged 18 years or older with permanent residence in Iceland and PCR-confirmed HCV were offered direct-acting antiviral (DAA) therapy. The programme used a multidisciplinary team approach in which people who inject drugs were prioritised. Nationwide awareness campaigns, improved access to testing, and harm reduction services were scaled up simultaneously. The number of infected people in the national HCV registry was used in combination with multiple other data sources, including screening of low-risk groups and high-risk groups, to estimate the total number of HCV infections. The number of people diagnosed, linked to care, initiated on treatment, and cured were recorded during the study. This study is registered with ClinicalTrials.gov, NCT02647879. FINDINGS: In February, 2016, at the onset of the programme, 760 (95% CI 690-851) individuals were estimated to have HCV infection, with 75 (95% CI 6-166) individuals undiagnosed. 682 individuals were confirmed to be HCV PCR positive. Over the next 3 years, 183 new infections (including 42 reinfections) were diagnosed, for a total of 865 infections in 823 individuals. It was estimated that more than 90% of all domestic HCV infections had been diagnosed as early as January, 2017. During the 3 years, 824 (95·3%) of diagnosed infections were linked to care, and treatment was initiated for 795 (96·5%) of infections linked to care. Cure was achieved for 717 (90·2%) of 795 infections. INTERPRETATION: By using a multidisciplinary public health approach, involving tight integration with addiction treatment services, the core service coverage targets for 2030 set by WHO have been reached. These achievements position Iceland to be among the first nations to subsequently achieve the WHO goal of eliminating HCV as a public health threat. FUNDING: The Icelandic Government and Gilead Sciences.

Lifetime alcohol intake and pattern of alcohol consumption in patients with alcohol-induced pancreatitis in comparison with patients with alcohol use disorder.

OBJECTIVE: To examine lifetime drinking patterns in men and women with alcohol-induced pancreatitis (AIP) in comparison with patients with alcoholic use disorder (AUD) without pancreatic disease. METHODS: Alcohol consumption patterns were assessed using a validated questionnaire, the Lifetime Drinking History (LDH), during an outpatient visit. Patients diagnosed with AIP were matched for gender and age (+/- 5 years) with patients with AUD in addiction treatment. RESULTS: A total of 45 patients with AIP (35 males, 10 females) and 45 AUD patients were included. Alcohol consumption patterns were not significantly different between males and females with AIP and those with history of acute AIP and chronic pancreatitis (CP). Alcohol consumption patterns of AIP and AUD patients were similar in terms of onset age and duration of alcohol consumption, lifetime alcohol intake and drinks per drinking day. A higher proportion of binge drinking was found among patients with AUD than those with AIP (median 1.00 vs. 0.94, p = .01). Males with AUD had lower onset age (15 vs. 16 years, p = .03), higher total amount of spirits (35520 vs. 10450 drinks, p = .04) and higher proportion of binge drinking (1.00 vs. 0.97, p = .01) than males with AIP, whereas females with AIP and AUD had similar drinking patterns. CONCLUSIONS: Alcohol drinking patterns and lifetime drinking history was similar in patients with AIP and patients with AUD. Males with AIP had lower total amount of spirits and lower proportion of binge drinking than those with AUD, suggesting the idiosyncratic etiology of AIP.

Polygenic risk scores for schizophrenia and bipolar disorder associate with addiction.

We use polygenic risk scores (PRSs) for schizophrenia (SCZ) and bipolar disorder (BPD) to predict smoking, and addiction to nicotine, alcohol or drugs in individuals not diagnosed with psychotic disorders. Using PRSs for 144 609 subjects, including 10 036 individuals admitted for in-patient addiction treatment and 35 754 smokers, we find that diagnoses of various substance use disorders and smoking associate strongly with PRSs for SCZ (P = 5.3 × 10-50 -1.4 × 10-6 ) and BPD (P = 1.7 × 10-9 -1.9 × 10-3 ), showing shared genetic etiology between psychosis and addiction. Using standardized scores for SCZ and BPD scaled to a unit increase doubling the risk of the corresponding disorder, the odds ratios for alcohol and substance use disorders range from 1.19 to 1.31 for the SCZ-PRS, and from 1.07 to 1.29 for the BPD-PRS. Furthermore, we show that as regular smoking becomes more stigmatized and less prevalent, these biological risk factors gain importance as determinants of the behavior.

Etiology unknown: Qualitative analysis of patient attributions of causality in scleroderma.

Background: Questions about the etiology of disease can concern patients living with any chronic disease and may impact disease-related adjustment. These causal attributions may be of particular interest when individuals are living with diseases for which etiologies have not been definitively identified, such as scleroderma. This study qualitatively explored patient attributions of causality for scleroderma. Methods: Patients with confirmed diagnoses of scleroderma responded to an open-ended prompt. The cross-sectional sample of scleroderma patients (N = 114) was recruited through registries maintained at the University of California, Los Angeles and University of California, San Diego Schools of Medicine and the Virginia Mason Medical Center. Content analysis was used to analyze the qualitative data and group the responses via an inductively derived codebook using the text analysis tool Dedoose Version 4.5. Results: Patients provided a variety of possible causes for scleroderma, which grouped into seven themes: (1) stress, (2) environment, (3) genetics, (4) medical conditions or surgeries, (5) diet, (6) medications or substance use, and (7) spirituality. Conclusion: Patients' causal attributions for scleroderma were varied, but many patients identified stress as a cause of scleroderma, often focusing on acute or chronic stressors that were present before disease onset. Identifying patient theories of causality for scleroderma can contribute to an increased understanding of disease-related behaviors and adjustment.

Modelling the elimination of hepatitis C as a public health threat in Iceland: A goal attainable by 2020.

BACKGROUND & AIMS: In Iceland a nationwide program has been launched offering direct-acting antiviral (DAA) treatment for everyone living with hepatitis C virus (HCV). We estimate (i) the time and treatment scale-up required to achieve the World Health Organization's HCV elimination target of an 80% reduction in incidence; and (ii) the ongoing frequency of HCV testing and harm reduction coverage among people who inject drugs (PWID) required to minimize the likelihood of future HCV outbreaks occurring. METHODS: We used a dynamic compartmental model of HCV transmission, liver disease progression and the HCV cascade of care, calibrated to reproduce the epidemic of HCV in Iceland. The model was stratified according to injecting drug use status, age and stage of engagement. Four scenarios were considered for the projections. RESULTS: The model estimated that an 80% reduction in domestic HCV incidence was achievable by 2030, 2025 or 2020 if a minimum of 55/1,000, 75/1,000 and 188/1,000 PWID were treated per year, respectively (a total of 22, 30 and 75 of the estimated 400 PWID in Iceland per year, respectively). Regardless of time frame, this required an increased number of PWID to be diagnosed to generate enough treatment demand, or a 20% scale-up of harm reduction services to complement treatment-as-prevention incidence reductions. When DAA scale-up was combined with annual antibody testing of PWID, the incidence reduction target was reached by 2024. Treatment scale-up with no other changes to current testing and harm reduction services reduced the basic reproduction number of HCV from 1.08 to 0.59, indicating that future outbreaks would be unlikely. CONCLUSION: HCV elimination in Iceland is achievable by 2020 with some additional screening of PWID. Maintaining current monitoring and harm reduction services while providing ongoing access to DAA therapy for people diagnosed with HCV would ensure that outbreaks are unlikely to occur once elimination targets have been reached. LAY SUMMARY: In Iceland, a nationwide program has been launched offering treatment for the entire population living with hepatitis C virus (HCV). A mathematical model was used to estimate the additional health system requirements to achieve the HCV elimination targets of the World Health Organization (WHO), as well as the year that this could occur. With some additional screening of people who inject drugs, Iceland could reach the WHO targets by 2020, becoming one of the first countries to achieve HCV elimination. The model estimated that once elimination targets were reached, maintaining current monitoring and harm reduction services while providing ongoing access to DAA therapy for people diagnosed with HCV would ensure that future HCV outbreaks are unlikely to occur.

Extended-Release Injectable Naltrexone (XR-NTX) With Intensive Psychosocial Therapy for Amphetamine-Dependent Persons Seeking Treatment: A Placebo-Controlled Trial.

OBJECTIVE: Explore the efficacy of extended-release injectable naltrexone (XR-NTX) for preventing relapse to amphetamine use. METHOD: Clinical trial of 100 amphetamine-dependent, treatment-seeking patients who were randomized to 6 monthly 380 mg doses of XR-NTX or matching placebo before entering intensive outpatient after varying lengths of inpatient treatment in Reykjavik, Iceland. Weekly urine drug tests, retention, and standardized instruments assessed efficacy. RESULTS: Of 169 approached, 100 were randomized. Although amphetamine dependence was the main reason for seeking treatment, three-quarters or more of participants had 1 or more other substance dependencies. Of 51 randomized to XR-NTX, 20 received 4 or more injections; of 49 assigned to placebo, 26 received 4 or more injections. Of the planned 2400 weekly urine drug tests, 1247 were collected (52%); 4% of these were positive for amphetamine, 8% for benzodiazepine, 7% for marijuana, 1% for cocaine, and 1% for opioid. XR-NTX had no effect on amphetamine-positive tests, retention, or other outcomes. Those providing half or more of their tests attended more weeks of treatment than those providing less than half of their tests (m = 10.76 vs 3.31; t (92) = 5.91, P < 0.0001), and 92 participants provided at least 1 test. CONCLUSIONS: Adding XR-NTX to the usual combination of inpatient and intensive outpatient treatment did not reduce amphetamine use. The low prevalence of substance use among collected urine samples, and the association between collected samples and weeks in treatment, was consistent with other studies showing that staying in treatment is associated with better outcomes.

Lifetime drinking history in patients with alcoholic liver disease and patients with alcohol use disorder without liver disease.

OBJECTIVE: To determine the differences in lifetime alcohol intake (LAI) and drinking patterns between patients with alcoholic liver disease (ALD) and alcohol use disorder (AUD) without notable liver injury and between males and females with ALD. METHODS: Alcohol drinking patterns were assessed using the Lifetime Drinking History (LDH) a validated questionnaire, during an outpatient visit. Patients with AUD, currently in addiction treatment, were matched for gender and age (±5 years) with the ALD group. RESULTS: A total of 39 patients with ALD (26 males and 13 females; median age 58) and equal number of AUD patients were included (median age 56 years). The onset age for alcohol drinking and duration of alcohol consumption was similar in ALD and AUD. The number of drinking days was higher in women with ALD than in women with AUD: 4075 [(3224-6504) versus 2092 (1296-3661), p = .0253]. The LAI and drinks per drinking day (DDD) were not significantly different between patients with ALD and AUD. Females with ALD had lower LAI than males with ALD: 32,934 (3224-6504) versus 50,923 (30,360-82,195), p = .0385, fewer DDD (p = .0112), and lower proportion of binge drinking as compared to males with ALD (p = .0274). CONCLUSIONS: The total LAI was similar in patients with ALD and AUD. The number of drinking days over the lifetime was associated with the development of ALD in females. Females with ALD had significantly lower alcohol consumption than men with ALD despite similar duration in years of alcohol intake which supports the concept of female propensity of ALD.

Sixteen-year follow-up of childhood avalanche survivors.

BACKGROUND: Every year a substantial number of children are affected by natural disasters worldwide. However, data are scarce on long-term psychological impact of natural disasters on children's health. Identifying risk factors and outcomes associated with the long-term sequelae of posttraumatic stress disorder (PTSD) can provide a gateway to recovery as well as enhancement of preventive measures. OBJECTIVE: Among childhood avalanche survivors, we aimed to investigate risk factors for PTSD symptoms and the relationship between socioeconomic status (SES) and PTSD symptoms in adulthood. METHODS: Childhood survivors (aged 2-19 at the time of exposure) of two avalanches were identified through nationwide registers 16 years later. The Posttraumatic Diagnostic Scale was used to assess current PTSD symptoms. One-way ANOVA was used to explore PTSD symptoms by background and trauma-specific factors, as well as associations with current SES. Predictors of PTSD symptoms were examined by multivariable regression analysis. RESULTS: Response rate was 66% (108/163). Results from univariate ANOVA analysis revealed that female sex was associated with PTSD symptoms (F=5.96, p<0.05). When adjusted for age and sex, PTSD symptoms were associated with lower education (F=7.62, p<0.001), poor financial status (F=12.21, p<0.001), and unemployment and/or disability (F=3.04, p<0.05). In a multivariable regression model, when adjusting for age and sex, lack of social support (t=4.22, p<0.001) and traumatic reactions of caregivers (t=2.49, p<0.05) in the aftermath of the disaster independently predicted PTSD 16 years post-trauma. CONCLUSIONS: Lingering PTSD symptoms after childhood exposure to a disaster may negatively influence socioeconomic development in adulthood. Strengthening children's support systems post-disaster may prevent the long-term sequelae of symptoms.

The Manifestations of Sleep Disturbances 16 Years Post-Trauma.

STUDY OBJECTIVES: Limited data exist on the association between trauma and sleep across developmental stages, particularly trauma experienced in childhood and sleep in adulthood. We assessed sleep quality across the developmental spectrum among avalanche survivors 16 years after exposure as compared to a matched comparison cohort. METHODS: Participants were survivors of two avalanche-affected towns (n = 286) and inhabitants of non-exposed towns (n = 357). Symptoms were assessed with respect to the survivors' developmental stage at the time of the disaster: childhood (2-12), adolescence (13-19), young adult (20-39), and adult (≥ 40). The Posttraumatic Diagnostic Scale, Pittsburgh Sleep Quality Index and Pittsburgh Sleep Quality Index PTSD Addendum were used. RESULTS: Overall PTSD symptoms were not associated with avalanche exposure in any age groups under study. However, survivors who were children at the time of the disaster were 2.58 times (95% CI 1.33-5.01) more likely to have PTSD-related sleep disturbances (PSQI-A score ≥ 4) in adulthood than their non-exposed peers, especially symptoms of acting out dreams (aRR = 3.54; 95% CI 1.15-10.87). Those who were adults at time of the exposure had increased risk of trauma-related nightmares (aRR = 2.69; 95% CI 1.07-6.79 for young adults aRR = 3.07; 95% CI 1.51-6.24 for adults) compared to their non-exposed peers. CONCLUSIONS: Our data indicate a chronicity of PTSD-related sleep disturbances, particularly among childhood trauma survivors. REM sleep disturbances may have different manifestations depending on the developmental stage at the time of trauma exposure.

Risk Factors for Posttraumatic Stress Symptoms Among Avalanche Survivors: A 16-Year Follow-Up.

Few natural disaster studies have assessed factors associated with posttraumatic stress disorder (PTSD) beyond a decade after trauma. Using North's disaster model as a framework, the aim of this study was to identify factors associated with clinically significant posttraumatic stress symptoms (CS-PTSDS) in avalanche survivors (n = 399) 16 years after the disaster. Completed self-report questionnaires were received from 286 (72%) survivors. CS-PTSDS were assessed with the Posttraumatic Diagnostic Scale. Predictors of CS-PTSDS in a multivariate analysis were secondary sequelae factors of lack of social support (adjusted relative risk [RR], 2.90; 95% confidence interval [CI], 1.37-6.13) and financial hardship in the aftermath of the trauma (adjusted RR, 2.47; 95% CI, 1.16-5.26). In addition, the community factor of providing assistance in the aftermath of the avalanche (adjusted RR, 1.95; 95% CI, 1.04-3.64) was inversely associated with CS-PTSDS. Screening for these factors may be useful in identifying those most vulnerable to developing chronic PTSD after this unique type of disaster.

Posttraumatic stress and other health consequences of catastrophic avalanches: A 16-year follow-up of survivors.

To date, no study has investigated the effects of avalanches on survivor's health beyond the first years. The aim of this study was to examine long-term health status 16 years after exposure to avalanches using a matched cohort design. Mental health, sleep quality and somatic symptoms among avalanche survivors (n=286) and non-exposed controls (n=357) were examined. Results showed that 16% of survivors currently experience avalanche-specific PTSD symptoms (PDS score>14). In addition, survivors presented with increased risk of PTSD hyperarousal symptoms (>85th percentile) (aRR=1.83; 98.3% CI [1.23-2.74]); sleep-related problems (PSQI score>5) (aRR=1.34; 95% CI [1.05-1.70]); PTSD-related sleep disturbances (PSQI-A score≥4) (aRR=1.86; 95% CI [1.30-2.67]); musculoskeletal and nervous system problems (aRR 1.43; 99% CI 1.06-1.93) and gastrointestinal problems (aRR 2.16; 99% CI 1.21-3.86) compared to the unexposed group. Results highlight the need for treatment for long-term PTSD symptoms and sleep disruption in disaster communities.

Psychometric properties of the Icelandic NEO-FFI in a general population sample compared to a sample recruited for a study on the genetics of addiction.

Personality traits are major determinants of social behavior influencing various diseases including addiction. Twin and family studies suggest personality and addiction to be under genetic influence. Identification of DNA susceptibility variants relies on valid and reliable phenotyping approaches. We present results of psychometric testing of the Icelandic NEO-FFI in a population sample (N=657) and a sample recruited for a study on addiction genetics (N=3,804). The Icelandic NEO-FFI demonstrated internal consistency and temporal stability. Factor analyses supported the five-factor structure. Icelandic norms were compared to American norms and language translations selected for geographical and cultural proximity to Iceland. Multiple discriminant function analysis using NEO-FFI trait scores and gender as independent variables predicted membership in recruitment groups for 47.3% of addiction study cases (N=3,804), with accurate predictions made for 69.5% of individuals with treated addiction and 43.3% of their first-degree relatives. Correlations between NEO-FFI scores and the discriminant function suggested a combination of high neuroticism, low conscientiousness and low agreeableness predicted membership in the Treated group.

The Adult Reading History Questionnaire (ARHQ) in Icelandic: Psychometric Properties and Factor Structure.

This article describes psychometric testing of an Icelandic adaptation of the Adult Reading History Questionnaire (ARHQ), designed to detect a history of reading difficulties indicative of dyslexia. Tested in a large and diverse sample of 2,187 adults, the Icelandic adaptation demonstrated internal consistency reliability (Cronbach's alpha = .92) and test-retest reliability (r = .93). Validity was established by comparing scores of adults who as children received ICD-10 diagnoses of specific reading disorder (F81.0; n = 419) to those of adults defined as nondyslexics (n = 679). ROC curve analysis resulted in an area under the curve of .92 (95% CI = .90, .93, p < .001) and a cutoff score of .43 with sensitivity of 84.5% and specificity of 83.7%. An exploratory factor analysis (n = 2,187) suggested three subscales, Dyslexia Symptoms, Current Reading, and Memory, the mean scores of which differed significantly among diagnosed dyslexics, relatives of dyslexics, and population controls. Our results support the applicability of the ARHQ in Icelandic as a self-report screening tool for adult dyslexia in Iceland.

The relationship between physical appearance concerns, disgust, and anti-fat prejudice.

This study examined relationships between physical appearance concerns (fear of fat, body image disturbance; BIDQ), disgust, and anti-fat prejudice (dislike, blame), and tested whether disgust mediates relationships between physical appearance concerns and anti-fat prejudice. Participants (N=1649; age=28 years) provided demographic data and completed measures of anti-fat prejudice, tendency to feel disgust, and physical appearance concerns. Univariate, multivariate, and mediation analyses were conducted. Univariate and multivariate associations were found between fear of fat, BIDQ, disgust, and anti-fat prejudice for women. For women only, mediation analyses showed that disgust partially mediated relationships between physical appearance concerns and dislike of fat people. For men, univariate and multivariate relationships were found between fear of fat, and dislike and blame of fat people, but disgust was not related to anti-fat prejudice. Newer constructs centering on physical appearance concerns and disgust appear promising candidates for understanding anti-fat prejudice.

Alcoholics Anonymous and the Minnesota Model of treatment in Iceland.

This study was undertaken to provide an initial characterization of the current status of patients admitted to an alcoholism treatment program in Iceland. Consistent with the Minnesota Model, 12-step facilitation has been a central component of the program since its inception. Of the 94 patients assessed in this study, 67% were male and 40% had attended over 90 AA meetings prior to admission. The mean number of drinking days during the month prior to admission was 15.51 days and the mean length of hospital stay was 12.32 days. At time of hospital discharge, 39% were referred to residential treatment. Significant predictors of referral to residential treatment included having attended less than 90 AA meetings prior to admission and length of stay.

Addictions and their familiality in Iceland.

Here, we provide an overview of previous family studies of addiction and present a new family study based on clinical data for more than 19,000 individuals who have been treated for addiction in Iceland over the last three decades. Coupled with the extensive Icelandic genealogy information, this population-based sample provides a unique opportunity for family studies. The relative risk (RR) was determined for up to fifth-degree relatives of probands diagnosed with alcohol, cannabis, sedative, and amphetamine dependence. We observe highly significant RR values for all substances ranging from 2.27 for alcohol to 7.3 for amphetamine, for first-degree relatives, and RRs significantly above 1 for distant relations, where the effect of shared environmental factors is minimized. The magnitude of risk in psychostimulant dependence is particularly striking. These findings emphasize the role of genetics in the etiology of addiction and highlight the importance of substance-specific effects.