Cognitive control and daily affect regulation in major depression and borderline personality disorder: protocol for an experimental ambulatory assessment study in Berlin, Germany

IntroductionAffective disturbances and difficulty in affect regulation are core features of major depressive disorder (MDD) as well as borderline personality disorder (BPD). Whereas depressed individuals are characterised by affective inertia, individuals with BPD are characterised by affective instability. Both groups have been found to use more maladaptive affect regulation strategies than healthy controls. Surprisingly, however, there have been hardly any studies directly comparing these two disorders to disentangle shared and disorder-specific deficits in affective dynamics and affect regulation.Furthermore, theoretical models link deficits in affect regulation to deficits in cognitive control functions. Given that individuals with MDD or BPD are both characterised by impairments in cognitive control, the present study will further examine the link between individual differences in cognitive control and disturbances in affect dynamics and regulation in the daily life of individuals with MDD or BPD.Methods and analysesWe will use a smartphone application to assess negative and positive affect as well as affect regulation strategies at eight times a day for 7 days. We will further employ four computerised tasks to assess two cognitive control functions, namely interference control and discarding irrelevant information from working memory. Our hypotheses will be tested using a multimethod approach. Power analyses determined a sample size of 159 (53 MDD, 53 BPD, 53 controls) to detect medium effect sizes.Ethics and disseminationEthics approval has been obtained from the Freie Universität Berlin. Data collection started in January 2017 and will last until the end of 2018. Results will be disseminated to relevant psychotherapeutic and patient communities in peer-reviewed journals, and at scientific conferences.