Objective: To examine in a pilot study inappropriate crying and laughing (also termed pseudobulbar affect (PBA)) and underlying mood disturbances in a large clinic based population of Parkinson's disease and movement disorder patients.
Background: PBA is characterized by uncontrollable laughter without mirth, or alternatively crying without the feeling of sadness. It is a common condition affecting more than one million people with neurological diseases. While PBA has been studied in many neurological diseases, little is known about its prevalence in movement disorders, or its relationship to more chronic mood disturbances. We carried out this pilot study to examine this relationship.
Methods: Seven hundred and nineteen out of 860 consecutive patients who visited our Movement Disorders Center met inclusion criteria (i.e. > or = 18 years of age, formal diagnosis by a movement disorder specialist, completion of PBA questionnaire, and absence of brain surgery including deep brain stimulation). All subjects were interviewed for symptoms of PBA during their visit. In addition, 661 of these patients completed both the Visual Analog Mood Scale (VAMS) and Beck Depression Inventory I (BDI-I).
Results: Thirty-seven of the 719 reported PBA symptoms; 75.7% (28/37) had pathological 'crying', 13.5% (5/37) had pathological 'laughing' and 10.8% (4/37) had both. The prevalence of PBA in individual diagnostic categories was: 4.7% (18/387) of idiopathic Parkinson's disease (PD), 2.7% (2/74) of primary dystonia, 3.1% (2/65) of essential tremor (ET), 7.8% (8/108) of patients with other forms of Parkinsonism, 21.7% (5/23) of psychogenic movement disorders, 0% (0/18) of patients with combined PD and ET, and 4.5% (2/44) of other movement disorders. Patients with PBA had a higher total BDI score (P=0.0278) and VAMS 'tiredness' score (P=0.0109). In patients on antidepressant therapy the prevalence of PBA was 7.1% compared to 2.7% in the group not on therapy (P=0.0094).
Conclusion: PBA was present in most movement disorders, but especially prevalent in parkinsonism. PBA patients in this cohort had more chronic depressive symptoms and tiredness.