The Effect of Hypnotic Suggestion on Return to Work, Functioning, and Cognition Following Acquired Brain Injury or Concussion: A Randomized Controlled Trial

Introduction Hypnotic suggestion may be an effective treatment modality for cognitive sequelae following acquired brain injury and concussion. A recent RCT demonstrated large effects of hypnotic suggestion on working memory following acquired brain injury. Analyses of interview-data from that RCT also indicated large effects on sleep and Patient-Reported Outcomes (PROs). Previous studies have similarly shown clinically notable effects in the cognitive domain, although these have some methodological shortcomings. While stroke and concussion patients exhibit non-impaired responsiveness to hypnotic suggestion, there is little literature on the effect of hypnotic suggestion on concussion patients. In a non-controlled study, it was found that vertigo was completely removed following 1-10 sessions of hypnosis in 63 out of 108 concussed patients and that vertigo was reduced in further 17 patients leaving only 28 (one in four) with no effect. In another smaller non-controlled study on patients with Mild Traumatic Brain Injury (MTBI), large effects on fatigue, anxiety, and depression were found. While the investigators have speculated about the mechanisms underlying the effect, the current goal of this research program is to provide the empirical basis for a verdict on whether hypnotic suggestion can be recommended for clinical practice. This is a pressing issue since brain injuries (stroke and TBI) constitute the world's second-most expensive health-related disability.

Long-term effects on everyday outcome measures is of utmost importance in clinical settings. However, no studies have investigated long-term (> 2 months) effects on Return to Work, participation in society, or fatigue, and only one high-quality RCT has been conducted. Here, the investigators present the protocol for an RCT that aims to fill in these gaps. The present protocol is an effectiveness study in a vocational-rehabilitation setting, but in other respects, it closely replicates the efficacy study by the primary investigator.

Objectives Estimate the effect of hypnotic suggestion on short- and long-term effects on Return to Work, participation in society, fatigue, and cognition. Given the promising findings in previous studies, the investigators hypothesize that hypnotic suggestion has positive effects in each of these domains.

Methods (setting) All patient activities take place at an out-patient municipal vocational rehabilitation center in Denmark, including recruitment, testing, and treatment. The center specifically offers support to increase labor market attachment.

Methods (recruitment) Potential participants were recruited from two departments in the vocational rehabilitation center: (1) a department specializing in citizens with brain-injury, concussion, whiplash, and related conditions. (2) A more general department which serviced a high rate of participants who had suffered a concussion. In both departments, the staff handed out participant information materials to all citizens who met inclusion 1-3 (age, etiology, and vocational history). The participants could optionally consent to giving their contact details to the project, contact the project by themselves, or decline. The first point of contact with the project was an oral information. The participant was given three days to consider consenting, though all participants made the decision immediately. After an initial screening by a project assistant, a list of eligible participants was sent to a dedicated non-blinded "coordinator" who randomly assigned participants to the groups while monitoring the balance between groups.