Pseudobulbar Affect (PBA) and Depression in Multiple Sclerosis

Background:

Pseudobulbar affect (PBA) is an under-recognized neurologic condition characterized by uncontrollable, inappropriate outbursts of laughing and/or crying that are incongruous or disproportionate to the patient’s emotional state; PBA occurs secondary to a variety of neurologic conditions, including multiple sclerosis (MS). Despite recent point prevalence epidemiological data from the PBA Registry Series (PRISM) of 5290 neurologic patients, MS clinicians do not feel comfortable detecting PBA or differentiating it from depression.

Objectives:

To explore the correlation between PBA and depression at a single MS Center. The impact of MS on patient quality of life (QOL) and use of antidepressants and antipsychotics in MS patients with and without PBA symptoms was also evaluated.

Methods:

Retrospective analysis of 31 consecutive MS patients who completed both the Center for Neurologic Study–Lability Scale (CNS-LS) to screen for PBA symptoms and the Beck Depression Inventory -II (BDI-II) to screen for depression. Twenty-three of the patients also completed a QOL measure consisting of the question, “How has your neurological condition affected your quality of life?” to be rated on an 11-point scale from 0 (not at all) to 10 (strongly affected). The CNS-LS subscores for laughing and crying were also analyzed separately, as was the crying specific question of the BDI-II,

Results:

10 patients (32%) scored a CNS-LS≥13. The mean and median BDI-II for patients with CNS-LS≥13 were both 12, while the mean and median BDI-II for patients with CNS-LS<13 were 11 and 9, respectively.  Overall, 77% of the patients were women: 90% of the patients with CNS-LS≥13 as compared to 71% with CNS-LS<13. There was no correlation between CNS-LS and BDI-II scores (Pearson correlation, 0.11), but there was a correlation between CNS-LS and BDI-II scores in the group of patients with CNS-LS≥13 (r=0.59). Interestingly, there was a stronger correlation between the CNS-LS laughing subscore and BDI-II (r=0.52) as opposed to the CNS-LS crying subscore and BDI-II (r=0.33). Higher BDI-II scores showed a positive correlation with greater QOL impact (r=0.37), while there was no correlation between CNS-LS scores and QOL impact in this cohort. MS patients with CNS-LS ≥ 13 were more likely than those with CNS-LS < 13 to be receiving nontricyclic antidepressants.

Conclusions:

Although the PBA epidemiology of 1215 MS patients (5290 overall) from PRISM will be published in 2013, there remains a need for clinicians to further characterize PBA symptoms and to differentiate PBA from depression. The unexpected correlation found between CNS-LS laughing subscores and BDI-II scores may be due to PBA causing depression (it is difficult to understand how the reverse may be true), but this needs to be further studied in larger cohorts. PBA can have a life altering effect on patients and their families, and this study helps to further elaborate the possibility of PBA being a causative factor for depression.