Emotional Changes in PLS

A PLS diagnosis changes more than physical function. It changes how you think about the future, how you relate to your body, and sometimes how you experience your own emotions. Some of these emotional changes come from the psychological challenge of the diagnosis itself. Others — like pseudobulbar affect — are neurological in origin. Both are real, both are worth addressing, and both are treatable.

Pseudobulbar affect: what it is and why it happens

Pseudobulbar affect (PBA) is a neurological condition characterized by involuntary, uncontrollable episodes of laughing or crying — or sudden switches between the two — that are excessive or inconsistent with the person's actual emotional state. It is not a psychiatric condition and it is not the same as emotional distress, though it can certainly be distressing.

The mechanism is a disruption of the cortical pathways that normally regulate emotional expression. In a healthy nervous system, the motor cortex maintains inhibitory control over brainstem circuits that produce laughing and crying. When upper motor neurons are damaged — as they are throughout the nervous system in PLS — this control is weakened, and emotional expression can be triggered by stimuli that would not normally provoke it. Something mildly amusing becomes uncontrollable laughter. A sentimental commercial brings on several minutes of crying. Frustration triggers laughing.

The key point is that the emotion produced in a PBA episode does not necessarily reflect what the person is actually feeling. Someone in the middle of a genuine conversation may start laughing uncontrollably without finding anything funny. Someone in a good mood may suddenly cry for two minutes. The episode is the brain misfiring, not an expression of inner state.

PBA occurs in a significant proportion of PLS patients with bulbar involvement — the corticobulbar tract involvement that produces spastic dysarthria and swallowing changes is the same pathway disruption that underlies PBA. It also occurs in approximately 30% of ALS patients. A 2024 paper in Cureus proposed an updated neurobiological model describing PBA as a network disorder linking emotion circuitry and motor output.

PBA treatment

PBA is genuinely treatable. The most commonly used options in PLS are:

Amitriptyline

Amitriptyline — a tricyclic antidepressant — is the first-line treatment for PBA in PLS at most centers. It is used at doses much lower than its antidepressant range, specifically for its effect on corticobulbar circuit regulation. It has the additional advantages of reducing sialorrhea (excess drooling, which can co-occur with bulbar involvement) and improving sleep. It has been used for decades in this context and clinicians are very familiar with managing its side effects, which include dry mouth, constipation, drowsiness, and at higher doses, cardiac rhythm effects.

Nuedexta

Nuedexta (dextromethorphan hydrobromide/quinidine sulfate) is the only FDA-approved medication specifically indicated for PBA. Clinical trials demonstrated significant reduction in PBA episodes, and it works through a different mechanism than antidepressants. A Phase 2 trial in 60 ALS patients also found that Nuedexta improved bulbar function more broadly — speech, swallowing, and salivation — beyond its PBA indication, published in AlzForum. The dosing is 20 mg/10 mg twice daily. Side effects include dizziness, diarrhea, and QT interval prolongation, which requires consideration in patients with cardiac conditions.

In most PLS management protocols, amitriptyline is tried first for PBA; Nuedexta is considered second-line or when amitriptyline is poorly tolerated.

SSRIs

Selective serotonin reuptake inhibitors (SSRIs) such as fluvoxamine are sometimes used for PBA, particularly when depression is also present and a single medication can address both. They are generally less targeted for PBA than the above options but may be appropriate depending on the full clinical picture.

PBA is not depression — how to tell the difference

This distinction matters because the treatments are different and the experiences feel different. PBA episodes are:

• Brief and intense — typically lasting seconds to a few minutes
• Triggered by minor stimuli
• Inconsistent with or disproportionate to actual emotional state
• Not associated with the persistent low mood, loss of interest, and cognitive features of depression

Depression, by contrast, is a sustained state — weeks of persistent low mood, loss of interest in activities that used to matter, changes in sleep and appetite, difficulty concentrating, and sometimes hopelessness. Depression and PBA can co-occur in the same person, and careful clinical assessment by someone familiar with motor neuron disease is the best way to sort out what is happening and what treatment is most appropriate.

The psychological shock of a PLS diagnosis

Receiving any motor neuron disease diagnosis is a profound disruption. Even when PLS is ultimately confirmed (rather than ALS), the path to that confirmation is often long and uncertain — years of symptoms, inconclusive testing, diagnostic categories that shift, and the looming question of what the disease is going to do.

Once a diagnosis is confirmed, most people move through a period of adjustment that is not linear and is not quick. There is grief — for the future that was assumed, for the physical capacities already lost, for the life that has to be reorganized. There is often anger, at the disease, at the diagnostic delay, sometimes at people who are healthy. There is frequently a period of information-seeking that can become exhausting.

These are not pathological responses. They are appropriate responses to a genuinely difficult situation. The goal of psychological support is not to prevent this adjustment process but to help you move through it without getting stuck.

Anxiety and the 23% conversion risk

One of the most specific sources of anxiety in PLS is the documented risk of conversion to ALS in the early years after diagnosis. Approximately 23% of patients initially presenting with pure upper motor neuron disease convert to ALS within the first four years — which is why definite PLS diagnosis requires at least four years of pure UMN signs without lower motor neuron involvement appearing.

If you are within that four-year window, or have recently received a "probable PLS" diagnosis, living with that uncertainty is not easy. Some people find that understanding the biology helps — knowing exactly what conversion would look like (fasciculations, muscle atrophy, EMG changes) and what the monitoring plan is gives a sense of active engagement rather than passive waiting. Others find that the uncertainty is better managed by focusing on the present rather than the future.

There is no single right approach. What matters is that this anxiety is acknowledged by your care team and addressed — not dismissed with reassurance that everything will probably be fine, but genuinely engaged with.

Depression: common, treatable, and worth naming

Depression is common among people with PLS and other motor neuron diseases. Research published in BMC Neurology (2015) found that depression in ALS/MND significantly affects quality of life independently of physical impairment — meaning that treating depression materially improves how people experience their lives, even when the underlying disease has not changed.

In PLS, depression is driven by multiple factors: the psychological weight of a progressive neurological diagnosis, increasing physical limitations, social isolation from reduced mobility, and sometimes the direct neurological effects of UMN disease on mood-regulating circuits.

Depression in this context is not weakness or failure to cope well. It is a medical condition with effective treatments. These include:

• Antidepressant medications — SSRIs and SNRIs are generally first-line; tricyclics (like amitriptyline) are useful if PBA co-occurs
• Psychotherapy — cognitive-behavioral approaches and acceptance-based therapies have evidence for chronic illness adjustment
• Social connection — isolation amplifies depression; PLS support groups and online communities provide meaningful connection
• Exercise — within safe limits (see exercise and rehab), regular physical activity has documented antidepressant effects

Illness cognitions: how you think about PLS matters

Research published in Frontiers in Neurology in 2021 introduced illness cognitions as a clinical framework for understanding behavioral and psychological symptoms in ALS and related diseases. Illness cognitions are the beliefs you hold about your disease — its cause, its timeline, its consequences, how much control you have, and what it means for your identity.

The research found that maladaptive illness cognitions — catastrophizing, fixed beliefs about complete loss of control, strong identity fusion with pre-illness self — are associated with higher anxiety, more depression, and greater caregiver burden. Cognitive-behavioral approaches that target these thought patterns can reduce psychological distress and improve care engagement.

This is not about positive thinking or denial. It is about the realistic recognition that how you understand your situation influences how you respond to it, and that responses can be shaped in ways that reduce suffering. Finding a therapist familiar with chronic illness or neurodegenerative disease — ideally one who can work with you on acceptance-based approaches — is worth the effort.

Finding a therapist who understands chronic illness

Not all therapists are equally equipped to work with someone living with a progressive neurological condition. A therapist who is effective in this context will not try to talk you out of your grief or push relentless optimism. They will work with you to find meaning within the situation you are actually in, help you maintain the relationships and activities that matter most, and develop genuine coping strategies rather than avoidance.

Your neurologist or multidisciplinary team social worker may be able to refer you to someone with relevant experience. ALS and MND organizations sometimes maintain directories of therapists familiar with motor neuron disease. Online therapy has become an important option for people with mobility limitations who would find travel to appointments difficult — the Frontiers in Psychiatry research (2023) found that digital mental health interventions were acceptable and potentially beneficial for people with motor neuron disease.