Ostrobothnia Depression Study (ODS) was conducted in the South Ostrobothnia hospital district of Finland during 2009-2014. ODS is a naturalistic, open label, non-randomized follow-up study on depression and related substance use disorders (SUD). The study focuses on several aspects concerning the relation of depression and SUDs, the efficacy of selected assessment and treatment protocols, characteristics and genetics of the participants and the use of related biomarkers in clinical practice. The misused substance in focus is alcohol. In this study, dual diagnosis (DD) is defined as the simultaneous presence of clinically diagnosed major depressive disorder (MDD) and alcohol use disorder (AUD). The study was approved by the local ethics committee. Written informed consent was collected from all participants.

Participants The participants were recruited in five outpatient clinics and in one psychiatric hospital ward in the South Ostrobothnia hospital district (population 200,000) during 1.10.2009 - 31.10.2013. Patients referred to psychiatric secondary services because of depressive symptoms, anxiety, self destructiveness, insomnia and alcohol or other substance related problems were screened with Beck depression inventory (BDI, version 1A). Patients with BDI score ≥ 17 at the screening phase were recruited in the study. The patients with a likely or verified psychotic disorders (ICD-10, F2*.** diagnosis) or organic brain disease were excluded.

A total of 242 patients were included in the study. Fifty-three (21.9%) patients were hospitalised at baseline. The participants were aged 17-64 years (mean 38.8 years, SD 12.2). Among the recruited were 148 females (61.2%) and 94 males (38.8%). The Mini International Neuropsychiatric Interview 5.0 (MINI) was made at the baseline to 219 patients.

At baseline 203 (84%) patients were prescribed antidepressive medication, 81% of cases either SSRI or SNRI as primary antidepressant). Antipsychotic medication was prescribed to 66 (28%) patients.

At the time of recruitment the participants were divided in two groups based on the AUDIT -score. The patients with baseline AUDIT-score ≥ 11 were categorized as patients with comorbid AUD and therefore dual diagnosis (DD+). The patients with AUDIT ≤ 10 were categorized as (DD-).

The clinical psychiatric evaluation was performed by a psychiatrist or other trained professional using the Mini International Neuropsychiatric Interview 5.0 (MINI). The symptoms of MDD were assessed by the Montgomery-Åsberg Depression Rating Scale (MADRS).

The patients received medication if the need for medical treatment was assessed by the psychiatrist responsible of the treatment. The use of psychotropic medications was recorded. The choice of medication was left for the clinician in charge.

All participants were also evaluated by three-dimensional model to select the following treatment intervention. The model has been developed by Kampman and Lassila in South Ostrobothnia hospital district and described in more detail in Finnish Medical Journal. The model was developed based on the need to have tools to better assess the patients with DD in clinical setting. The model can be used for defining the patients' problem according to three treatment related factors (diagnosis, substance use problem, level of functioning). The model consists of three dichotomous assessments each leading to score of 0 or 1 points according to difficulty of the problem. The factors assessed are 1) psychiatric diagnosis (non-psychotic/psychotic; 0/1 points), 2) difficulty of SUD (moderate/difficult; 0/1 points) and 3) patients level of functioning according to Global Assessment of Functioning (GAF) -scale (good functioning/poor functioning; 0/1 points). The given points are then added together to form an overall score from 0 points (modest DD problem) to 3 points (most difficult DD problem).

Treatment interventions The treatment interventions included antidepressive medication (SSRI or other), Behavioral Activation therapy (BA) and FRAMES intervention, and Motivational interview (MI) In participants with AUDIT ≤ 10 (DD-) the intervention started with focus on depression (antidepressive medication and BA). In patients with AUDIT ≥ 11 (DD+) the intervention started with focus on AUD. If AUD was evaluated as moderate (duration less than 2 years, most of the days sober during the last month) the first treatment selected could be either FRAMES or MI. If AUD was assessed to be severe (duration more than 2 years, active use most of the days during last month, poly-substance use, GAF < 50) the intervention was supposed to start with MI. The intervention was implemented by the staff person responsible of the appointments of certain patient (a nurse or a psychologist) who had received training for the use of selected interventions. The duration of MI was set to approximately 3 (2-5) appointments. The minimum duration of BA was set to 4 appointments.

Follow-up The follow-up included appointments with clinical research nurse at 6, 12 and 24 months points. During these appointments the severity of and the recovery from depression was evaluated by MADRS, alcohol use was evaluated by AUDIT, the information on substance use relapses was collected, and the MINI-interview was repeated at 12 months point. Additionally, the following information was collected: 15D-quality of life scale, GAF-scale, laboratory tests (at 6 months: a blood count, electrolytes, creatinine, liver function), Body Mass Index, waist, smoking status.

Inclusion Criteria:

Patients referred to psychiatric secondary services because of

1. Depressive symptoms
2. Anxiety
3. Self-destructiveness
4. Insomnia
5. Alcohol or other substance related problems, and had Beck depression inventory (BDI, version 1A) score at least 17 at the screening phase.

Exclusion Criteria:

• A likely or verified ICD-10 F2 category diagnosis (psychotic disorders).
• Organic brain disease