Abstract
ObjectivesTo differentiate the relation between the structure and timing of rest‐activity patterns and symptoms of impulsivity and mood instability in bipolar disorder (BD), borderline personality disorder (BPD) and healthy controls (HC).MethodsEighty‐seven participants (31 BD, 21 BPD and 35 HC) underwent actigraph monitoring for 28 days as part of the Automated Monitoring of Symptom Severity (AMoSS) study. Impulsivity was assessed at study entry using the BIS‐11. Mood instability was subsequently longitudinally monitored using the digital Mood Zoom questionnaire.ResultsBPD participants show several robust and significant correlations between non‐parametric circadian rest‐activity variables and worsened symptoms. Impulsivity was associated with low interdaily stability (r = −0.663) and weak amplitude (r = −0.616). Mood instability was associated with low interdaily stability (r = −0.773), greater rhythm fragmentation (r = 0.662), weak amplitude (r = −0.694) and later onset of daily activity (r = 0.553). These associations were not present for BD or HCs. Classification analysis using actigraphic measures determined that later L5 onset reliably distinguished BPD from BD and HC but did not sufficiently discriminate between BD and HC.ConclusionsRest‐activity pattern disturbance indicative of perturbed sleep and circadian function is an important predictor of symptom severity in BPD. This appears to validate the greater subjective complaints of BPD individuals that are sometimes regarded as exaggerated by clinicians. We suggest that treatment strategies directed towards improving sleep and circadian entrainment may in the future be investigated in BPD.
Highlights
Bipolar disorder (BD) and borderline personality disorder (BPD) are psychiatric disorders that share overlapping core symptoms of impulsivity and mood instability
We demonstrated that individuals with BPD exhibit rest-activity patterns that are suggestive of phase delayed circadian clock function compared with stable BD and healthy controls [23]
Mood instability in BPD but not healthy controls (HC) or BD was associated with greater rhythm fragmentation (IV: r = 0.662, P = 0.006), later onset of daily activity (M10 onset: r = 0.553, P = 0.028) and greater nocturnal arousal (L5 activity: r = 0.560, P = 0.028)
Summary
Bipolar disorder (BD) and borderline personality disorder (BPD) are psychiatric disorders that share overlapping core symptoms of impulsivity and mood instability. Impulsivity, broadly defined, comprises a behavioural pattern of disinhibition, reward-seeking and action without forethought [1]. In both conditions, impulsivity is associated with deleterious outcomes such as increased aggression, substance abuse, self-harm and acts of suicide [2,3,4,5]. Mood instability is characterised by bursts of intense affect and marked difficulties in regulating mood and behaviour [6]. In BD and BPD, poorly managed mood instability predicts poorer prognosis, greater number of hospital admissions and suicidal behaviour [7,8,9]. Explicit treatment of impulsivity [10] and stabilisation of mood [11] should both be considered targets for improvement
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