Intrusive nightmares are a hallmark symptom of post-traumatic stress disorder (PTSD), contributing significantly to psychiatric comorbidities, impaired physical health and diminished social functioning. Currently, no pharmacological treatments are specifically approved for managing PTSD-related nightmares. However, emerging evidence suggests that adrenoceptor-targeting agents may offer therapeutic potential. Notably, clonidine and doxazosin have demonstrated efficacy in reducing PTSD-associated nightmares, as indicated by findings from open-label studies and small randomised controlled trials.

This study is a multicentre, double-blind, randomised (1:1:1), placebo-controlled, parallel-group interventional trial. A total of 189 eligible patients will be randomly assigned to receive clonidine, doxazosin or placebo, with a once-daily oral dose administered at bedtime for 10 weeks. The primary efficacy endpoint is the Clinician-Administered PTSD Scale B2 score at week 10, which measures the frequency and intensity of nightmares. Secondary efficacy endpoints include other PTSD-specific symptoms. Additionally, the safety of clonidine and doxazosin will be assessed.

The study was approved by the Ethics Committee of the State of Berlin (Ethik-Kommission des Landes Berlin) (Reference: 21-683-Haupt-IV E 13), on 14 March 2022 and by the relevant federal authority, the Bundesinstitut für Arzneimittel und Medizinprodukte, reference 4044931. The study was conducted in accordance with the relevant guidelines and regulations. The study results will be published in peer-reviewed journals and presented at both national and international conferences.

NCT05360953, EudraCT 2021-000319-21.

The recent pandemic caused by SARS-CoV-2 had a profound global impact. While many individuals recovered from COVID-19, some developed long-lasting symptoms that significantly disrupted daily life. The WHO defines this condition as post-COVID-19 condition (PCC). Common symptoms include fatigue, dyspnoea, sleep disturbances and cognitive difficulties. Increasing evidence suggests that PCC is a multifactorial condition, shaped not only by biomedical but also psychological and social factors. This article presents the protocol of the Basel Long COVID Cohort Study (BALCoS), which aims to improve understanding of PCC by capturing clinical, functional and psychosocial aspects through repeated assessments over the course of 1 year.

BALCoS is a prospective, single-site cohort study. Inclusion criteria include either a probable or confirmed history of SARS-CoV-2 infection with persistent symptoms consistent with the WHO definition of PCC, sufficient German language skills and age ≥18 years. At baseline, we collected detailed information on previous SARS-CoV-2 infections, symptom history, reinfections, COVID-19 vaccination status and pre-existing medical conditions. The study includes standardised psychometric assessments, physical performance tests, ecological momentary assessments (EMAs), neurocognitive testing and blood sample collection. Assessments are scheduled at baseline and at 3-month, 6-month and 12-month follow-up. All participants complete psychometric assessments at each time point. Blood samples are only collected at baseline. Neurocognitive testing and physical performance measures are collected at baseline and 12-month follow-up for in-person participants only. Participants who are unable to attend in person complete a remote version of the study, excluding these in-clinic assessments. EMAs are initiated the day after each time point and consist of eight questions over 10 consecutive days. The study is exploratory in nature, with a target sample size of 120 participants. BALCoS is part of the Horizon Europe Long COVID project, a multinational interdisciplinary research consortium integrating mechanistic, clinical and interventional studies.

The study was approved by the Ethics Commission of Northwest and Central Switzerland (BASEC-ID: 2023–00359) and is registered at ClinicalTrials.gov (ID: NCT05781893). All participants provide written informed consent. Study findings will be disseminated through peer-reviewed publications.

NCT05781893.