Prevalence, correlates and treatment of nightmares in secondary mental healthcare

Abstract

Nightmares are associated with psychopathology. The prevalence of nightmares in the general population is 2-5%. However, the impact of nightmares when comorbid mental disorders are present is unknown. We investigated the prevalence of nightmares in a population with diverse mental disorders. Over the course of eighteen months all patients who started their treatment at GGz Centraal de Meregaard (secondary mental healthcare) in Almere (NL), filled out validated questionnaires about nightmares. About 30% met the criteria for nightmare disorder according to strict DSM-IV-TR criteria. None of these patients had a DSM-IV-TR diagnosis of nightmare disorder in their medical files. Furthermore we compared patients with and without nightmare disorder regarding their psychopathology symptoms. The patients with nightmare disorder had higher rates of general psychopathology and personality pathology symptoms. Although this was a correlational study and therefore the direction of the effect remains an open question, the data strongly suggests that nightmares are indicative of more severe forms of psychopathology. Currently ‘imagery rehearsal therapy’ (IRT) is the recommended treatment for nightmares. With IRT the script of the recurring nightmare is changed into a new dream, which is imagined during the day. However the effects of IRT in a population with comorbid mental disorders remains unknown. We did a randomized controlled trial (RCT) on IRT in a patient sample with diverse mental disorders and nightmares from GGz Centraal in Amersfoort, Hilversum and Almere (NL). We administered six sessions of individual IRT bi-weekly as an add-on to treatment as usual (TAU). We found that IRT diminished nightmare frequency and distress, as well as general psychopathology and posttraumatic stress disorder (PTSD) symptoms, to a moderate degree when compared to TAU. The effects were largely sustained at the three-month follow-up. The effect sizes in our current study were smaller than in most previous RCTs, which may be explained by the fact that our sample was heterogeneous regarding psychopathology symptoms and comorbidity. Another reason may be that in our study recording of nightmares –which has known beneficial effects – was done in both the IRT and TAU conditions. The effects of IRT in our study exceeded those of recording by itself. We reported a follow-up study addressing the long-term effects six months and nine months after the end of the treatment for the IRT group. We found that the positive effects of IRT were sustained at follow-up. In summary, nightmare disorder is highly prevalent in patients with mental disorders in secondary mental healthcare, although none of the patients had a DSM-IV-TR diagnosis of nightmare disorder in their medical files. One in every three patients suffers from nightmares and these patients report more severe psychopathology in comparison to patients without nightmare disorder. Our study stresses the importance of careful assessment of nightmares in patients with diverse mental disorders. IRT successfully ameliorated nightmare frequency, nightmare distress and overall mental health complaints and psychopathology symptoms in this sample. IRT is effective and feasible to use in addition to treatment as usual in secondary mental healthcare.