The quality of parent-adolescent communication has been found to be associated with adolescent mental health. However, little is known about the association of parent-adolescent communication and adolescent mental health in the context of psychiatry inpatient treatment.

This study aims to find out whether self-reported parent-adolescent communication quality at the time of admission to psychiatry predicts the treatment outcome in terms of symptom reduction 6 months later in an adolescent inpatient sample. It also aims to track changes in adolescent self-reported communication quality in the course of inpatient treatment and afterwards (2, 4 and 6 months after admission) to see whether improvement predicts treatment outcome, with treatment outcome being defined as symptom reduction to baseline. As a secondary endpoint, it will be assessed whether a placement of the adolescent outside the family was considered during treatment and whether self-reported communication quality at the time of admission predicts the consideration of placement outside the family.

The main hypotheses of the study are:

1a Higher quality of self-reported parent-adolescent communication at baseline is positively associated with higher symptom reduction from baseline (psychiatry admission, t0) to 6 months after admission (t3).

1. b Higher improvement of parent-adolescent communication from t0 to t3 is positively associated with higher symptom reduction from t0 to t3.
2. Higher quality of self-reported parent-adolescent communication at baseline is negatively associated with consideration of the adolescent's placement outside the family during treatment.

The hypotheses 1a and 1b will be assessed with a linear regression model, hypothesis 2 will be assessed with a logistic regression model.

Covariates that will be taken into consideration are symptom severity at baseline, socioeconomic status of the family, adolescent gender, age, and comorbidity. Sensitivity analyses will be calculated for inpatient treatment duration and outpatient treatment duration after discharge from the hospital.

Symptom severity as the primary outcome is assessed with three measures: YSR (Youth Self-Report), DISYPS-ANG (Diagnostik-System für Psychische Störungen - Angststörungen) and DISYPS-DES Diagnostik-System für Psychische Störungen - Depressive Störungen). The relevant scale will be chosen according to the primary clinical diagnosis: If the primary diagnosis is anxiety (F40-F41), DISYPS-ANG will be used for the primary outcome. If the primary diagnosis is depression (F32-F33), DISYPS-DES will be used. If any other condition is the primary diagnosis, the YSR total scale will be used. Raw values of the DISYPS and the YSR will be transformed into z-values.

Inclusion Criteria:

• Admission to inpatient care unit of the adolescent psychiatry at the University Medical Center Hamburg-Eppendorf.

Exclusion Criteria:

• Severe symptom burden at admission
• Lack of knowledge of the German language.

Adolescents aged 14;1 to 17;12 years with a diagnosis of a mental disorder requiring inpatient treatment at a psychiatric site.