Symptoms of ALS

Amyotrophic lateral sclerosis (ALS) is a neurodegenerative disorder in which worsening muscle weakness leads to movement problems, as well as trouble swallowing, speaking, and breathing. Patients can also experience digestive issues, mental health problems, and changes in behavior.

Also known as Lou Gehrig’s disease, after the famous baseball player who was forced to retire following his diagnosis, ALS is caused by damage to motor neurons, the specialized nerve cells that control muscle movement.

Symptoms of ALS can occur at any age but usually begin around ages 55 to 75. The condition is a progressive neurodegenerative disorder, meaning that symptoms often start mild and become more severe over time. Though the rate of progression varies widely among individuals, many people lose their ability to walk, speak, and breathe independently within five years.

Muscular symptoms

Muscle weakness is the hallmark symptom of ALS. It usually starts off mild and may affect only one body part, but gradually becomes more severe and widespread as the disease progresses.

How ALS muscle weakness manifests varies significantly among individuals, but patients are commonly divided into two groups based on their initial ALS symptoms.

• limb-onset ALS: Weakness starts in the arms and/or legs, often in the hands, feet, calves, or forearms. This occurs in around two-thirds of ALS patients.
• bulbar-onset ALS: Weakness first affects the muscles around the head and neck, called the bulbar muscles. This occurs in around a quarter to a third of patients.

For a smaller group of people, muscle weakness may start in abdominal or breathing muscles.

Regardless of where muscle weakness begins, as the disease progresses, it essentially always develops into paralysis. Most people with ALS will have limited or no ability to move voluntarily in the later stages of the disease.

Other muscle-related manifestations of ALS may include:

• muscle twitches (fasciculations)
• muscle wasting (atrophy)
• muscle fatigue
• muscle cramps and stiffness (spasticity)
• abnormal reflexes
• shaking or tremors
• muscles that become hardened, tightened, and shortened (contractures)

Breathing difficulties

Muscles in the chest and abdomen work to move air in and out of the lungs during breathing. ALS-related weakness in these muscles leads to breathing difficulties, which affect nearly all patients at some point. This can start early on, though it’s more common for breathing problems to develop later in the disease course.

In addition to feelings of overt breathlessness, weakness in the respiratory system can manifest as gasping or labored breathing, sometimes called air hunger, and frequent yawning or sighing, which are the body’s attempts to bring in more oxygen.

Because of the way the body changes its use of breathing muscles during sleep, slow and shallow breathing at night (nighttime hypoventilation) may begin before obvious breathing difficulties while awake. The symptoms of this nighttime hypoventilation can be subtle, but may include:

• morning headaches, confusion, or irritability
• unrefreshing sleep or waking up often throughout the night
• shortness of breath when lying flat
• persistent daytime fatigue or sleepiness

Lung muscle weakness often leads to a weak cough, making it difficult to clear mucus from the lungs. This can set the stage for infections and pneumonia, which are common complications for ALS patients.

By the later stages of the disease, ALS patients will usually require a ventilator to help them breathe. Respiratory failure, when the lungs are not able to adequately supply the body with enough oxygen to function, is common and is the leading cause of death in ALS, typically occurring within five years of symptoms first appearing.

Speech problems

Weakness in the muscles around the mouth and jaw can cause speech problems, referred to as dysarthria. This symptom affects 80%-95% of people with ALS at some point in the disease course.

Speech problems don’t usually develop until later disease stages in people with limb-onset ALS, but they are among the most common early signs of ALS in people with bulbar-onset disease.

Dysarthria in ALS can manifest as:

• slow, slurred, and difficult-to-understand speech
• difficulty articulating words and pronouncing certain consonants
• a nasal, breathy, weak, strained, or hoarse voice
• trouble moving the tongue
• difficulty controlling the pitch, volume, or rhythm of speech

In addition, patients often feel tired after speaking and may find it difficult to project their voices due to weakened lung muscles. As a result, people with ALS tend to talk less and use shorter sentences as their disease progresses.

In late stages of the disease, many people with ALS rely on technologies to allow communication without speech, such as text-to-voice apps or communication boards.

Difficulty swallowing

Weakness in the muscles of the lips, tongue, or throat, which collectively enable swallowing, leads to difficulty swallowing (dysphagia) in more than 80% of patients. These problems usually occur in the later stages of the disease, though they may occur early in some patients with bulbar-onset disease.

Difficulty swallowing may not be obvious, especially in the early stages when these issues may be mild. Signs of dysphagia in ALS may include:

• frequent coughing or choking on food
• food or liquid spilling through the mouth or nose
• food sticking in the throat after swallowing
• pooling of saliva in the mouth that may look like drooling
• unintentional weight loss due to a lack of proper nutrition

Difficulty swallowing can increase the risk of food or liquid entering the windpipe by mistake, a condition called aspiration. This can cause choking and set the stage for airway infections or pneumonia.

As ALS progresses into its later stages, a feeding tube usually becomes necessary to ensure patients receive needed nutrition.

Digestive issues

Many people with ALS experience gastrointestinal problems, which can range from mild to severe. These are thought to arise due to dysfunction of the nerves and muscles that regulate the movement of food through the digestive tract. Certain ALS medications may also cause digestive issues as a side effect.

Specific digestive issues that are common in ALS include:

• constipation and cramping
• acid reflux, which can cause burning or discomfort in the chest and throat
• nausea and vomiting
• delayed gastric emptying, which occurs when the stomach does not empty as quickly as it should

Anxiety and depression

As with any serious illness, ALS has a huge impact on the day-to-day lives of patients, as well as their loved ones and caregivers. This can cause depression, anxiety, and other mental health challenges at any stage of the disease.

Manifestations of these mental health problems are varied and can include:

• persistent feelings of sadness, worthlessness, and/or hopelessness
• excessive worry, guilt, and/or fear
• trouble sleeping or sleeping too much
• eating too much or too little
• irritability and a tendency to get angry easily
• persistent low energy and fatigue
• thoughts of suicide

A number of strategies can provide support for ALS patients and caregivers to help them cope with anxiety and depression, including medications, counseling or therapy, support groups, mindfulness programs, and relaxation techniques.

Cognitive issues

While ALS was previously thought not to affect the mind, more recent research has shown that up to half of ALS patients will experience cognitive or behavioral changes at some point during the course of their disease.

The most common cognitive change is a decline in executive function, the set of skills that enable a person to plan actions and regulate behavior to achieve goals and complete tasks. Cognitive changes that people with ALS might notice include:

• difficulty concentrating or shifting attention from one thing to another
• embarrassing, inappropriate, or uncharacteristic behavior
• becoming fixated on certain ideas or repeating things excessively
• aggression, agitation, and strong emotional reactions that are hard to control
• trouble with empathy and lack of judgment
• forgetting the meaning or spelling of words

For many, cognitive impairments are relatively mild — they may be noticeable, but are not severely disruptive to everyday life. However, up to 20% of people with ALS will develop dementia, which broadly refers to cognitive declines substantial enough to interfere with a person’s daily functioning.

The majority of ALS patients who do develop dementia will be diagnosed with a form of it called frontotemporal dementia (FTD), characterized by damage to the brain’s frontal and temporal lobes. In contrast to the relatively mild cognitive challenges faced by many with ALS, FTD can lead to profound changes in personality and behavior.

Pseudobulbar affect

More than a third of ALS patients experience pseudobulbar affect, characterized by sudden bursts of emotional displays that are unrelated to a person’s emotional state — laughing though nothing is funny, or bursting into tears when nothing is sad. These displays, which can occur several times per day, often seem inappropriate and can be embarrassing.

This symptom is not the same as anxiety or depression, in which emotional expressions may match internal mood. A person with depression, for example, may cry because they genuinely feel sad. Moreover, depression and anxiety are often sustained over time, while pseudobulbar affect in ALS involves very brief outbursts, lasting seconds or minutes.

Pseudobulbar affect is thought to result from disruptions in neural circuits that control emotional expression, though the exact mechanism remains unclear.

Other symptoms

In addition to muscle weakness, cognitive changes, and mood issues, ALS can cause:

• skin problems
• urinary urgency, or the need to urinate suddenly
• erectile dysfunction
• pain in the muscles and joints

In the latter stages of the disease, people with ALS may also be more likely to develop serious complications like pulmonary embolism, which occurs when a clot blocks blood flow in the lungs, and abnormal heartbeats known as cardiac arrhythmias.