PRISM: a novel research tool to assess the prevalence of pseudobulbar affect symptoms across neurological conditions

Abstract

Background: Pseudobulbar affect (PBA) is a neurological condition characterized by involuntary, sudden, and frequent episodes of laughing and/or crying, which can be socially disabling. Although PBA occurs secondary to many neurological conditions, with an estimated United States (US) prevalence of up to 2 million persons, it is thought to be under-recognized and undertreated. The PBA Registry Series (PRISM) was established to provide additional PBA symptom prevalence data in a large, representative US sample of patients with neurological conditions known to be associated with PBA.

Methods: Participating clinicians were asked to enroll ≥20 consenting patients with any of 6 conditions: Alzheimer's disease (AD), amyotrophic lateral sclerosis (ALS), multiple sclerosis (MS), Parkinson's disease (PD), stroke, or traumatic brain injury (TBI). Patients (or their caregivers) completed the Center for Neurologic Study-Lability Scale (CNS-LS) and an 11-point scale measuring impact of the neurological condition on the patient's quality of life (QOL). Presence of PBA symptoms was defined as a CNS-LS score ≥13. Demographic data and current use of antidepressant or antipsychotic medications were also recorded.

Results: PRISM enrolled 5290 patients. More than one third of patients (n = 1944; 36.7%) had a CNS-LS score ≥13, suggesting PBA symptoms. The mean (SD) score measuring impact of neurological condition on QOL was significantly higher (worse) in patients with CNS-LS ≥13 vs <13 (6.7 [2.5] vs. 4.7 [3.1], respectively; P<0.0001 two-sample t-test). A greater percentage of patients with CNS-LS ≥13 versus <13 were using antidepressant/antipsychotic medications (53.0% vs 35.4%, respectively; P<0.0001, chi-square test).

Conclusions: Data from PRISM, the largest clinic-based study to assess PBA symptom prevalence, showed that PBA symptoms were common among patients with diverse neurological conditions. Higher CNS-LS scores were associated with impaired QOL and greater use of antipsychotic/antidepressant medications. These data underscore a need for greater awareness, recognition, and diagnosis of PBA.

Figure 1. Published PBA symptom prevalence estimates by primary neurological condition.

Shading indicates multiple estimates. AD, Alzheimer’s disease; ALS, amyotrophic lateral sclerosis; CNS-LS, Center for Neurologic Study–Lability Scale; MS, multiple sclerosis; PBA, pseudobulbar affect; PD, Parkinson’s disease; PRISM, PBA Registry Series; TBI, traumatic brain injury. ^aPatient interview; ^bCNS-LS ≥13 (higher estimate), CNS-LS ≥21, lower estimate; ^c Poeck criteria: pathological affect could be mood congruent (emotional lability) or incongruent (pathological laughing and crying); ^dRetrospective review of hospital or clinic records; ^eMailed questionnaire; ^fEmotional lability questionnaire (ELQ); ^gAscertainment method unknown; ^hPatient interview, Poeck criteria; ⁱBrief questionnaire (uncontrollable laughing/crying when not happy/sad); ^jCNS-LS ≥13 (highest estimate), CNS-LS ≥17 (middle estimate), Cummings Involuntary Emotional Expression Disorder criteria (lowest estimate); ^kCNS-LS ≥17 (lower estimate), CNS-LS ≥13 (higher estimate); ^lPathological Laughing and Crying Scale (PLACS) ≥10 and score of ≥2 on PLACS items 2 (frequency), 13 (loss of voluntary control), and 18 (distress/embarrassment); ^mPatient interview House (lower estimate), and Kim (higher estimate) criteria; ⁿPatient interview House criteria; ^oPatient interview Kim criteria; ^pPatient interview Kim criteria (lower estimate; n = 516) and modified Kim criteria (patient report only without corroboration from relatives; higher estimate); ^qPatient interview Kim criteria at hospital admission (lower estimate) and at 3 months (higher estimate) following stroke.

Figure 2. Sample interim PRISM registry report available to activated sites.

CNS-LS, Center for Neurologic Study–Lability Scale; PRISM, PBA Registry Series.

Figure 3. PBA symptom prevalence by CNS-LS threshold.

AD, Alzheimer’s disease; ALS, amyotrophic lateral sclerosis; CNS-LS, Center for Neurologic Study–Lability Scale; MS, multiple sclerosis; PBA, pseudobulbar affect; PD, Parkinson’s disease; PRISM, PBA Registry Series; TBI, traumatic brain injury.

Figure 4. Impact of neurological condition on quality of life by CNS-LS threshold.

*P<0.0001 compared with CNS-LS <13; two-sample t-test. CNS-LS, Center for Neurologic Study–Lability Scale. Note: Group with CNS-LS ≥21 is a subset of the group with CNS-LS ≥13.

Figure 5. Psychotropic medication use by CNS-LS threshold.

*P<0.0001 compared with CNS-LS <13; chi-square test. CNS-LS, Center for Neurologic Study–Lability Scale; TCA, tricyclic antidepressant(s). Note: Group with CNS-LS ≥21 is a subset of the group with CNS-LS ≥13.