To examine the prevalence and characteristics of pathological laughing and crying in progressive supranuclear palsy (PSP).

Pseudobulbar affect (PBA), or pathological laughing and crying, is a poorly understood clinical phenomenon that lacks standardized diagnostic criteria. Prior studies have suggested that PBA is common in certain neurodegenerative disorders, such as PSP, but large cohort studies on the prevalence and features of PBA in PSP are lacking.

We conducted a retrospective chart review to evaluate laughing and crying in 210 individuals with PSP who presented to the University of California, San Francisco Memory and Aging Center between 1998 and 2023. Using objective criteria, two raters recorded whether each patient exhibited laughing and crying behaviors that were deemed to be frequent, uncontrollable, or inappropriate. The ratings were then used to classify individuals as having probable or possible PBA. We next compared these classifications with the clinician’s diagnosis of PBA at the time of the evaluation.

The mean age of the patients at the time of the clinical evaluation was 69.2 ± 7.3 years, and the sample consisted of 54% males. Our chart review identified PBA in 53 (25%) of the individuals with PSP: 27 (13%) with probable PBA and 26 (12%) with possible PBA. The clinicians who conducted the evaluations, in contrast, diagnosed PBA in only 30 individuals (14%) in the cohort. There was agreement between the chart review classifications and the clinician ratings of PBA in 21 (78%) of individuals with probable PBA in the chart review and in 7 (27%) of the individuals with possible PBA in the chart review.

Our results suggest that pathological laughing and crying is common in PSP.  A better understanding of the clinical phenomenology of PBA will be important for clinicians to evaluate this symptom.