(BPT) – – Meet David Diehl. In 1998, David was diagnosed with Multiple Sclerosis (MS), losing sight in his left eye two years later.

Then there’s Charles Davis, a former NFL player for the Cincinnati Bengals and Tampa Bay Buccaneers. Charles suffered a stroke in 2010, which left him with limited control of his body and greatly affected his speech.

And finally, meet Shevoney Darden, who suffered a traumatic brain injury (TBI) after a near fatal car accident in her early 20s and life has never been the same.

What do these three people with very different stories all have in common? Each suffers from a distressing neurologic condition called pseudobulbar affect, or PBA. PBA is caused by an underlying neurologic condition, such as MS, stroke, TBI, Lou Gehrig’s disease, Alzheimer’s disease or other dementias, and is characterized by unpredictable crying and/or laughing episodes that can be frequent and intense. Due to a lack of awareness and knowledge of PBA, it is often mistaken as depression or just a part of the primary neurologic disease – when in fact, it’s a separate, treatable condition.

Crying and laughing are among the two most fundamental human emotional expressions, so imagine not having control of them – how would you cope? For people like David, Charles and Shevoney suffering from PBA, this is an everyday struggle in addition to managing the other symptoms of their primary neurologic condition. And they are not alone. PBA is thought to affect nearly 2 million Americans nationwide, however many remain undiagnosed.

Due to its unpredictable nature, PBA often causes embarrassment for those living with the condition, particularly in public settings. Sometimes these crying or laughing episodes are so disruptive they can interfere with routine activities or cause patients to avoid social situations altogether. David, for example, was very active speaking in his church before the onset of his PBA symptoms. Because his laughing outbursts were so unpredictable, he stopped his regular speeches to the congregation. In fact, David once attended a friend’s funeral and laughed uncontrollably in the middle of the service which caused him great distress.

For Shevoney, her frequent laughing PBA episodes have made it difficult to attend college classes to earn her degree in medical administration. She feels her colleagues view her as immature, but in reality, she cannot control her laughing even when the subject isn’t funny.

Charles, too, is living a very different life from his former glory days in the NFL. In addition to his loss of mobility and slurred speech from his stroke, he now copes with his unpredictable crying displays and is adjusting to a new way of life.

Behind every brave patient is often a devoted caregiver, who serves as a moral supporter. With their devoted wives, Arlene and Mari Lou respectively, at their sides, David and Charles have the support system they need in order to persevere. And with the help of her close family, Shevoney is determined to graduate from college and lead a more normal life.

If someone you love has PBA, he or she may be embarrassed by his or her crying or laughing outbursts and reluctant to talk about their condition, so make sure they know you understand these episodes are involuntary and out of their control. Also remind your loved one PBA is a neurologic condition, not a mental state, causing a “short circuit” in the brain that triggers these episodes.

If you or someone you know is dealing with a brain injury or neurologic condition associated with PBA, here are the symptoms to watch out for. Ask your doctor about PBA if you or someone you love: