Involuntary emotional expression disorder (IEED) tends to be underdiagnosed and misdiagnosed by physicians and often remains untreated, according to a recent study that used a novel method to estimate its prevalence among patients with several different neurological disorders.1
IEED, also known as pseudobulbar affect, emotional lability, and pathological laughing and crying, is characterized by uncontrollable episodes of crying or laughter that are exaggerated or incongruent with the underlying mood. In addition, sudden, angry outbursts may occur in IEED.2 These episodes are often embarrassing and can be socially debilitating for the patient.
IEED has been associated with multiple sclerosis (MS), amyotrophic lateral sclerosis (ALS), Parkinson disease (PD), traumatic brain injury (TBI), stroke, and Alzheimer disease (AD) and other dementias. According to some estimates, nearly 2 million persons may be affected in the United States.1
PREVALENCE UNDERESTIMATED
In a study presented on May 1, 2007, at the 59th Annual Meeting of the American Academy of Neurology in Boston, a research team led by Walter Bradley, DM, professor and chairman emeritus of the Department of Neurology, Miller School of Medicine, University of Miami, surveyed over 2000 patients (or their caregivers) with neurological diseases or injuries associated with IEED to determine the prevalence of this disorder.
Bradley and colleagues1 adopted a novel approach, which was to work with Harris Interactive (best known for the Harris Poll) and its online database of a nationally representative sample of American adults. The researchers identified from the Harris Interactive Chronic Illness Panel 2318 patients in whom 1 of 6 underlying neurological conditions (MS, PD, ALS, TBI, stroke, and AD and other dementias) had been diagnosed. Patients or their caregivers were then invited to participate in an online survey designed to estimate the prevalence of IEED in the 6 underlying diseases. Data were weighted to match the disease populations in the United States.
"This way of selecting patients differs from the standard clinic chart review and is perhaps a better way of obtaining community-wide data related to individual diseases and symptoms," Bradley said in an interview with Applied Neurology.
The investigators used 2 clinically validated scales: the Pathological Laughing and Crying Scale (PLACS) and the Center for Neurological Study Lability Scale (CNS-LS) to establish the prevalence of IEED. The surveys also collected information about patient-physician interaction regarding potential diagnosis and treatment of IEED.
The researchers used a cutoff score of 13 on the PLACS and 21 on the CNS-LS to distinguish between persons with or without IEED. The overall prevalence of IEED in the 6 diseases was estimated to be 10.1% (based on a PLACS score of 13 or greater) and 9.5% (based on a CNS-LS score of 21 or greater). These data indicate that between 1.8 and 1.9 million patients with neurological disorders in the United States experience comorbid IEED, based on estimates from various professional and governmental organizations of the number of persons affected by the 6 underlying neurological disorders.
Rates for specific neurological conditions were highest for ALS (32.5%) and lowest for PD (3.6%). Only 59% of patients with IEED symptoms had discussed them with a physician. Of these, fewer than half had received a diagnosis (most often depression) or any treatment.
These results, according to Bradley, show that IEED is a more frequent problem than had previously been thought and that it is underdiagnosed and undertreated by physicians. "This is unfortunate," he said, "because IEED seriously hampers social interactions and can have a significant deleterious effect on patients' and their families' quality of life."
DIFFICULT TO DIAGNOSE
Peter Rabins, MD, MPH, professor of psychiatry and codirector of the Division of Geriatric Psychiatry and Neuropsychiatry at Johns Hopkins University School of Medicine in Baltimore, also thinks that physicians often fail to properly diagnose IEED. One reason, he said, is that crying is the most common manifestation, which is often interpreted as a symptom of depression.
Another reason why IEED may sometimes be difficult to diagnose is that many patients, especially those in the advanced stages of AD, are unable to describe their emotions. "So, what you see is someone who suddenly cries intermittently. It is hard to know whether he is depressed, has IEED, or is having what is called a catastrophic reaction," Rabins said.
He related clues that might help physicians decide whether a particular patient has IEED or some other disorder such as depression. One clue is that patients who are able to describe their emotional state often say that they don't feel particularly sad, or else that they don't feel as sad as their crying would suggest. "In patients with ALS or MS, or even stroke, who also have IEED, the feeling-state doesn't match the expressed emotion," he explained.
Other important differences between depression and IEED also may help physicians differentiate these 2 disorders. In addition to crying, depressed patients typically express thoughts of helplessness, hopelessness, and guilt. These sentiments are usually absent in patients with IEED. Other symptoms that are often present in patients with depression but not in those with IEED include disturbances in sleep or appetite.3
Another typical characteristic of IEED, according to Rabins, is that episodes of crying or laughing come on very suddenly and usually stop very quickly. "These episodes are often triggered by an event that has a minor emotional relevance to it," he said.
In addition, the laughing that may occur in patients with IEED "is not really laughing," commented Hillel Panitch, MD, professor of neurology and director of the Clinical Neurotrials Unit at the University of Vermont College of Medicine in Burlington. "It's just a problem controlling the facial muscles, and it looks like the patient is giving you a big grin when he's really not," he explained.
In patients with MS, the symptoms of IEED typically begin during the later stages of the disease, according to Panitch. "In MS, IEED usually appears after there have been several attacks or relapses, and there is some damage to the pathways that control emotional expression," he said.
IEED also tends to appear during the later stages of AD; however, it can occur at any stage, according to Rabins. "In my clinical experience, IEED can occur at any stage, depending on where the lesions are. So certainly in ALS, but even in MS, some patients who have relatively mild, although definite neurological impairments, can develop symptoms of IEED."
