Amyotrophic lateral sclerosis, known as ALS, is a serious neurological disease that progressively weakens the body’s muscles. It affects nerve cells in the brain and spinal cord and gradually reduces muscle control over time.
What is ALS

ALS is a disorder that targets nerve cells in the brain and spinal cord. As these cells deteriorate, muscle control is steadily lost. The condition is also referred to as Lou Gehrig’s disease, named after the baseball player who was diagnosed with it.
An unknown cause

The exact cause of ALS remains unclear. In a small percentage of cases, the disease is inherited. For most people, however, no specific cause can be identified.
Early symptoms

Initial signs often include muscle twitching and weakness in an arm or leg. Some individuals may experience difficulty swallowing or slurred speech in the early stages.
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Progressive worsening

Over time, ALS affects the ability to move, speak, eat and breathe. Muscles weaken as more nerve cells gradually die.
Common symptoms

Symptoms vary depending on which nerve cells are affected. They may include difficulty walking, frequent tripping or falling, weakness in the legs, feet or ankles, and reduced strength or clumsiness in the hands.
Muscle cramps and emotional changes

Some people experience muscle cramps and twitching in the arms, shoulders and tongue. Episodes of uncontrolled crying, laughing or yawning may occur, along with changes in thinking or behavior.
Pain and the senses

Pain is generally not a prominent feature, either in the early or later stages of the disease. ALS typically does not affect bladder control or the senses, including taste, smell, touch and hearing.
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Motor neurons

ALS damages the motor neurons responsible for voluntary movements such as walking and speaking. There are upper motor neurons, which run from the brain to the spinal cord, and lower motor neurons, which extend from the spinal cord to the muscles.
When nerve cells degenerate

Both upper and lower motor neurons gradually deteriorate and die in ALS. When these nerve cells are damaged, they can no longer send signals to the muscles, causing the muscles to lose function.
Genetic risk

Around 10 percent of people with ALS have an inherited form of the disease. In these cases, children have a 50 percent chance of inheriting the responsible gene.
Age and sex

The risk of ALS increases with age, rising up to the age of 75. The condition is most common between the ages of 60 and the mid-80s. Before age 65, slightly more men than women are affected, but this difference largely disappears after age 70.
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Environmental factors

Smoking has been associated with an increased risk of ALS, and women who smoke may face a particularly elevated risk, especially after menopause. Exposure to lead or other substances at home or in the workplace has also been examined as a possible factor. Studies suggest that people who have served in the military may have a higher risk, although the reason remains uncertain.
Breathing complications

As the disease progresses, the muscles involved in breathing weaken. Some people require a mask ventilator at night, while others may choose a surgically created opening in the neck connected to a ventilator. Respiratory failure is the most common cause of death. About half of those diagnosed die within 14 to 18 months, although some live 10 years or longer.
Speech and communication

Many individuals develop weakness in the muscles used for speech. Speech may become slower and slurred, eventually making it difficult for others to understand. Alternative communication methods and assistive technologies can help maintain communication.
Nutrition and dementia

Difficulty swallowing can lead to malnutrition, dehydration and an increased risk of pneumonia if food or liquids enter the lungs. A feeding tube may help ensure adequate nutrition and hydration. Some people with ALS experience problems with language and decision-making, and a portion are diagnosed with frontotemporal dementia.
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Kilder: Mayo Clinic
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