Course of subthreshold manic symptoms and related risk factors in the general population: A three-year follow-up study

ObjectivesSubthreshold manic symptoms (subM) are a risk factor for the onset and recurrence of bipolar disorder (BD). Individuals with subM may benefit from preventive interventions, however, their development is hampered by a lack of knowledge on subM prevalence and subsequent course. This study examines subM characteristics, course, and risk factors for an unfavourable course. MethodsIn a Dutch representative, population-based sample aged 18-64 (N =4618), we assessed subM, defined as the occurrence of manic core symptoms (elation/irritability), without meeting full DSM-IV criteria for BD I or II in the past 3years. Comparison groups had either no manic symptoms (noM) or hypomania/mania in the context of BD (mBD) in the past 3years. Furthermore, we differentiated a mild and moderate type of subM, based on the number of manic symptoms. A subsequent three-year course was assessed prospectively. ResultsSubM had a three-year prevalence of 4.9%. Its prevalence, characteristics, and course were in between noM and mBD, and there were few differences between mild and moderate subM. Over the 3-year follow-up, 25.0% of individuals with subM had persistent subM and another 6.1% transitioned to mBD. Eleven significant risk factors for this unfavourable course were found. The most important were a history of depression/dysthymia (OR 3.75, p <= 0.001), living alone (OR 2.61, p <= 0.01) and elevated neuroticism score (OR 1.21, p <= 0.001). ConclusionsThis study supports the validity and clinical relevance of subM as a BD prodrome. It demonstrates that subM symptoms often persist or increase during follow-up and identifies 11 risk factors that are associated with an unfavourable course.

Automated summary

This study examines the characteristics, course, and risk factors for an unfavourable course of subthreshold manic symptoms (subM), which are a risk factor for bipolar disorder. The study found that subM had a three-year prevalence of 4.9% and that 25.0% of individuals with subM had persistent symptoms and 6.1% transitioned to full manic episodes. The study also identified 11 risk factors for an unfavourable course, including a history of depression, living alone, and elevated neuroticism score.