Pseudobulbar Affect

Pseudobulbar affect (PBA) is a condition characterized by bouts of sudden, uncontrolled laughter or crying that occur in some people with amyotrophic lateral sclerosis (ALS). These outbursts often seem out of proportion or incongruent with the situation, and do not necessarily match how the person is actually feeling. They can be quite severe and can occur as often as several times a day.

PBA may affect a person’s employment or relationships. Embarrassment or anxiety about the episodes may cause patients to become isolated.

What causes PBA?

PBA may occur as a result of brain injury or neurological disorders, including ALS. The exact cause of the condition is not known, but scientists think it results from a disruption in the brain’s neural circuits that control the expression of emotions.

It is estimated that as many as 15 to 45 percent of all ALS patients experience these episodes. Uncontrolled crying is more common than uncontrolled laughing.

How is PBA diagnosed?

Pseudobulbar affect is sometimes confused with mood disorders such as depression or bipolar disorder. However, depression is an ongoing feeling of sadness, whereas the crying episodes in PBA are brief and not necessarily related to sadness. Moreover, other symptoms of depression, such as appetite loss or sleep disturbances, are usually absent in people with this affect. But, it is important to remember that it is possible for an ALS patient to have both depression and PBA.

PBA is usually diagnosed during a neurological exam with the doctor asking about the patient’s symptoms. Keeping a symptom diary and sharing it with the doctor can be helpful. The diary may include such details as when symptoms occur, how long they last, and the circumstances surrounding the episodes.

Patients may be asked to complete a questionnaire about their symptoms, including the ability to control their laughter and crying. One commonly used assessment tool is the Center for Neurologic Study lability scale (CNS-LS).

Treatment for PBA

A medication called Nuedexta has been approved by the U.S. Food and Drug Administration (FDA) to treat pseudobulbar affect. It contains the chemicals dextromethorphan and quinidine.

Other treatments for PBA include a class of medicines known as selective serotonin reuptake inhibitors (SSRIs) and tricyclic antidepressants.


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