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PubMed This is a summary of 20 peer-reviewed journal articles Updated
Neurology · Pseudobulbar Affect

What Causes Uncontrollable Laughing and Crying in ALS?

At a Glance

Uncontrollable laughing and crying in ALS is caused by a neurological symptom called Pseudobulbar Affect (PBA). It occurs when ALS damages the nerve pathways that control emotional expression. PBA is a physical reflex, not a mood disorder like depression, and can be managed with specific medications.

In this answer

4 sections

01

The “Broken Brake” in Your Brain

02

PBA vs. Depression

03

Coping in the Moment

04

Managing PBA with Medications

If you find yourself crying uncontrollably when you aren’t sad, or laughing out loud when nothing is funny, you are not alone. In ALS, this is a neurological symptom called Pseudobulbar Affect (PBA) [1][2]. It is caused by damage to specific nerves in the brain that control how you express emotions, leading to a disconnect between how you feel on the inside and what you show on the outside [3][4].

The “Broken Brake” in Your Brain

To understand PBA, it helps to know how the brain normally manages emotions. The frontal part of your brain decides how to express an emotion (like laughing or crying) and sends a signal down to the brainstem to carry out the action [5][6]. The frontal brain also acts as a “brake,” stopping you from laughing or crying at the wrong times.

ALS damages the upper motor neurons—the nerve cells that connect the brain to the brainstem [3][4]. When these pathways (called the corticobulbar tracts) are damaged, the “brake” is lost [3][7]. The emotional expression centers in your brainstem become hyperactive and fire off without your permission [8][1]. This is a physical, neurological problem, not a sign of emotional weakness. While laughing and crying are the most common symptoms, PBA can also sometimes manifest as intense frustration or anger [1].

PBA vs. Depression

Because PBA often involves crying, patients and families frequently confuse it with depression [2][9]. It is critical to understand the difference:

  • Depression is a mood disorder. A depressed person feels deep sadness, hopelessness, and grief for extended periods.
  • Pseudobulbar Affect (PBA) is a disorder of emotional expression [5]. The crying (or laughing) comes on suddenly, often with no clear trigger, and stops just as quickly [1]. The outburst often doesn’t match how the person actually feels [2].

While it is normal to experience grief and depression while living with ALS, PBA is a separate physical symptom [2]. However, having unpredictable outbursts can be embarrassing and socially isolating, which can certainly worsen your overall mood [9].

Explaining PBA to Loved Ones
Family members may misinterpret your outbursts as extreme emotional pain, which can be deeply distressing for everyone. Educating them that PBA is a physical reflex caused by ALS—not a reflection of your true feelings—can greatly reduce anxiety [10][11]. You might even consider carrying a small card that says, “I have a neurological condition that causes me to laugh or cry uncontrollably. Please just give me a moment to let it pass.”

Coping in the Moment

When an episode starts, behavioral self-control techniques can sometimes help you manage its severity [12]. Try these strategies:

  • Take slow, deep “belly breaths” to help reset your nervous system.
  • Change your physical position or move to another room to break your focus.
  • Break eye contact and shift your attention to an unrelated object.

Managing PBA with Medications

You do not have to manage these outbursts alone, and medical treatments can significantly help reduce their frequency.

  • Nuedexta (dextromethorphan and quinidine): This is the only medication specifically FDA-approved to treat PBA in ALS [13][14]. Dextromethorphan acts on specific brain receptors to help restore control over emotional pathways, while a tiny dose of quinidine prevents your body from breaking down the dextromethorphan too quickly [15][16]. Clinical trials show it effectively reduces PBA episodes [17][18]. However, because quinidine can cause heart rhythm issues (such as QT prolongation), Nuedexta is not safe for people with a history of heart failure or those taking certain other medications [18]. Common side effects include dizziness, diarrhea, and headaches [15][17].
  • Antidepressants (Off-Label): Sometimes doctors prescribe low doses of certain antidepressants (like SSRIs or tricyclic antidepressants) to help manage PBA symptoms [19][10]. They are used “off-label” for their effect on brain chemicals, not necessarily to treat depression. Like all medications, they carry risks of side effects and interactions.

If you are experiencing these uncontrollable episodes, tell your neurologist. A simple questionnaire (called the Center for Neurologic Study-Lability Scale, or CNS-LS) can help your doctor confirm if it is PBA and get you started on a safe treatment plan [20][5].

Common questions in this guide

What causes uncontrollable laughing and crying in ALS?
Uncontrollable laughing and crying in ALS is a physical symptom called Pseudobulbar Affect (PBA). It happens when ALS damages the nerve pathways between the brain and brainstem, removing the 'brake' that normally controls emotional expressions.
Is Pseudobulbar Affect the same as depression?
No, PBA and depression are different. Depression is a mood disorder involving prolonged sadness, while PBA is a neurological reflex where sudden crying or laughing outbursts do not match how you actually feel on the inside.
Are there medications to treat uncontrollable crying in ALS?
Yes, medical treatments are available to reduce these emotional outbursts. Nuedexta is a medication specifically FDA-approved for PBA, and doctors may also prescribe low doses of certain antidepressants off-label to help manage the symptoms.
How can I stop a PBA episode when it starts?
When an episode begins, you can try behavioral techniques to manage its severity. Slow, deep belly breaths, changing your physical position, or breaking eye contact and shifting your focus to an unrelated object can help reset your nervous system.
What should I tell my family about my emotional outbursts?
It is helpful to explain to loved ones that your outbursts are a physical, neurological symptom of ALS, not a sign of emotional weakness or extreme grief. Educating them about PBA can greatly reduce their anxiety and prevent misunderstandings.

Questions to Ask Your Doctor

Curated prompts to bring to your next appointment.

  1. 1.Are my crying or laughing episodes likely caused by Pseudobulbar Affect, or could they be related to something else?
  2. 2.If I decide to try Nuedexta, how will my current ALS medications and cardiac history affect whether it is safe for me?
  3. 3.How long does it typically take to see an improvement in PBA symptoms once starting a new medication?
  4. 4.If Nuedexta is not a good fit for me due to side effects or heart risks, what off-label options do you recommend?
  5. 5.Can you refer me or my family to a support group or counselor to help us better navigate the social challenges of PBA?

Questions For You

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References

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This page provides information on Pseudobulbar Affect (PBA) in ALS for educational purposes only. Always consult your neurologist for an accurate diagnosis and treatment plan for any emotional or neurological symptoms.

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