approved on October 29, 2010. In the pivotal multicenter study that led to its approval, the "Objectives...[were] to evaluate the safety, tolerability, and efficacy of two different doses of AVP-923 [Dextromethorphan/quinidine combination]...when compared to placebo." The conditions and results of that study are as follows: Epidemiology Prevalence estimates place the number of people with PBA between 1.5 and 2 million in the United States alone, which would be less than 1% of the U.S. population even at the high end of the estimate. Some argue that the number is probably higher and that clinicians underdiagnose PBA. However, the prevalence estimate of 2 million is based on an online survey. Self-selected computer-savvy patients in at-risk groups evaluated their own symptoms and submitted their self-diagnoses. No doctor or clinic confirmed the data. Motivation to participate could have been influenced by the presence of symptoms, which would have skewed the results. The actual prevalence could very well be quite a bit lower than estimated. History The Expression of the Emotions in Man and Animals by Charles Darwin was published in 1872. In Chapter VI, "Special Expressions of Man: Suffering and Weeping", Darwin discusses cultural variations in the acceptability of weeping and the wide differences in individual responses to suffering. The chapter contains the following sentence: Terminology Historically, there have been a variety of terms used for the disorder, including pseudobulbar affect, pathological laughter and crying, emotional lability, emotionalism, emotional dysregulation, or more recently, involuntary emotional expression disorder. The term pseudobulbar (pseudo- + bulbar) came from the idea that the symptoms seemed similar to those caused by a bulbar lesion (that is, a lesion in the medulla oblongata). Terms such as forced crying, involuntary crying, pathological emotionality, and emotional incontinence have also been used, although less frequently. In popular culture Arthur Fleck, the central character of the 2019 film Joker, displays signs of pseudobulbar affect, which are said to be what Joaquin Phoenix used as inspiration for his character's signature laugh. In the 2019 movie Parasite, the character Ki-woo sustains head trauma, and although it is not clearly mentioned that he's affected by pseudobulbar affect, he mentions not being able to stop laughing when thinking about all the events that occur in the movie. In the 2020 movie Naan Sirithal, the character Gandhi (Hiphop Tamizha Aadhi) suffers from pseudobulbar affect due to all the stress he suffers from various parts of his life gets