Affective instability across the lifespan in borderline personality disorder – a cross‐sectional e‐diary study

Abstract

Objective Longitudinal and cross‐sectional studies suggest that affective instability is inversely related to greater age in borderline personality disorder ( BPD ). However, existing studies relied on retrospective self‐reports of perceived instability. We examined affective instability in everyday life in patients with BPD and healthy controls ( HC s) by age in a cross‐sectional e‐diary study. Methods Two hundred and sixty female participants between 14 and 53 years of age (130 patients with BPD and 130 HC s) carried an e‐diary over 4 days. The e‐diaries emitted a prompting signal in approximately hourly intervals asking participants to rate their current affective state, that is valence (ranging from pleasant to unpleasant) and tense arousal (ranging from calm/relaxed to restless/under tension). Results Multilevel analyses revealed a significant interaction of age and group predicting affective instability (valence: F (1,255.6) = 7.59; P < 0.01; tense arousal: F (1,252) = 6.08; P < 0.01), suggesting that affective instability significantly declines with greater age in patients with BPD . Controlling for the number of comorbid disorders and BPD severity did not change the results, illustrating an inverse relationship between age and affective instability in BPD (significant interaction of age*group for valence: F (1,238.7) = 5.74; P < 0.02 and tense arousal: F (1,235.2) = 5.28; P < 0.02). Conclusion Affective instability during daily life declines with greater age in BPD . This decline is irrespective of comorbidity and BPD severity.