Abstract
<p>Introduction: Patients with long-term stress-related disorders report cognitive symptoms across a broad range of domains; however, neuropsychological test results often do not align with these self-reported cognitive difficulties. One potential explanation for this discrepancy is that patients may perform well during a single, undisturbed test session but have difficulties sustaining cognitive performance over time following prolonged mental effort, which can be conceptualized as reduced cognitive endurance. This may have implications for work participation and hinder return to work unless adequately addressed. Methods and analysis: This study protocol describes a longitudinal study aimed at investigating cognitive endurance in patients with long-term stress-related disorders. Moreover, we will explore the association between cognitive endurance and each of the following variables: self-reported fatigue and cognitive function, self-assessed work ability, and return to work. Sixty patients with long-term stress-related disorders will be recruited from a nonrandomized multicentre controlled trial evaluating work-focused cognitive behavioural therapy in a primary healthcare setting. Sixty healthy controls will be recruited through advertisement. Cognitive endurance is assessed through repeated cognitive testing in the morning and afternoon of a regular working day, at two time points: baseline and six months after study enrolment. The cognitive tests focus on short-term and working memory, attention and processing speed, and executive functions. Prior to the assessments, participants complete questionnaires concerning trait fatigue, self-reported cognitive function and work ability. Moreover, state fatigue is assessed through self-report questionnaires administered during the assessment day. Sick-leave registry data is used to investigate return to work for the patient group. The study evaluates a novel method for assessing cognitive functioning in stress-related disorders and can provide insights into how variations in cognitive functioning over the course of a workday relate to different aspects of fatigue, as well as to functioning in everyday life and at work.Ethics and dissemination: The study has been approved by the Swedish Ethical Review Authority (Dnr 2025-01713-01; 2025-07089-02). All participants will receive written and oral information about the study and provide written informed consent. Results will be disseminated in peer-reviewed scientific journals, at academic conferences and through communication with key stakeholders. Trial registration: The trial was registered 2 April 2026 at the Open Science Framework (https://doi.org/10.17605/OSF.IO/CYSGX).</p>