Amyotrophic Lateral Sclerosis – Symptoms and Causes
Overview
ALS (Amyotrophic Lateral Sclerosis) is a progressive neurological disease that harms nerve cells in the brain and spinal cord.
This damage leads to declining muscle control that worsens over time. The disease is commonly known as Lou Gehrig’s disease, named after the famous baseball player who received this diagnosis.
The exact cause of ALS remains unknown for most patients. Some cases (a small percentage) are passed down through families.
Early ALS signs often include:
- Muscle twitching
- Weakness in limbs
- Slurred speech
- Swallowing difficulties
As the disease progresses, it affects the muscles needed for essential functions like movement, speaking, eating, and breathing. The condition is fatal and currently has no cure.
Signs and Symptoms
ALS affects people differently based on which nerve cells are damaged. It typically begins with muscle weakness that gradually worsens over time. Common symptoms include:
- Difficulty walking or performing everyday tasks
- Frequent tripping and falling
- Weakness in legs, feet, or ankles
- Hand weakness or reduced dexterity
- Speech problems or swallowing difficulties
- Muscle cramps and twitching, especially in the arms, shoulders, and tongue
- Uncontrolled laughing, crying, or yawning
- Changes in thinking or behavior
ALS usually starts in the limbs (hands, feet, arms, or legs) before spreading to other body parts. As nerve cells die, muscles grow progressively weaker. This eventually impacts basic functions like chewing, swallowing, speaking, and breathing.
Most people don’t feel pain during early ALS stages, and pain remains uncommon even as the disease advances. Bladder control generally remains intact. The senses—including taste, smell, touch, and hearing—generally remain unaffected.
What Causes ALS?
ALS affects the nerves that control muscle movement. These nerve cells are called motor neurons and come in two types:
- Upper motor neurons – travel from the brain to the spinal cord.
- Lower motor neurons – extend from the spinal cord to muscles throughout the body.
When someone has ALS, both types of motor neurons slowly break down and die. If these neurons don’t function properly, muscles can’t receive movement signals, resulting in weakness or paralysis.
For most people with ALS (about 90%), doctors don’t know exactly what causes the disease. Only about 10% of cases have a clear genetic link that can be identified.
Scientists think ALS likely results from a mix of:
- Genetic factors
- Environmental triggers
- Possible risk factors being studied include age, military service, and exposure to certain toxins
Research continues as experts try to understand how genes and environment interact to cause this disease. Finding the exact cause may help develop better treatments in the future.
Risk Factors
Several factors may increase a person’s chance of developing ALS:
Genetic Factors
- About 10% of ALS cases are hereditary
- Children of people with hereditary ALS have a 50% chance of inheriting the risk gene
Age and Sex Differences
- Risk rises with age until about 75 years old
- Most common between ages 60 and mid-80s
- Men face a slightly higher risk before age 65
- After age 70, the risk becomes equal between men and women
Environmental Influences
Smoking has been strongly linked to ALS development:
- Confirmed environmental risk factor
- Postmenopausal women who smoke appear particularly vulnerable
Exposure to certain substances may play a role:
- Lead exposure in workplace or home environments
- Various chemicals and toxins have been studied
- No single agent has been definitively identified as causing ALS
Military Service Connection
- Research shows military personnel have higher ALS rates
- Possible triggers include:
- Exposure to specific metals or chemicals
- Physical trauma
- Viral infections
- Extreme physical exertion
These risk factors help researchers identify individuals who may develop ALS, but they do not ensure that someone will actually get the disease.
Problems That May Arise
Breathing Difficulties
ALS often affects the muscles needed for breathing. As these muscles get weaker, patients might need help breathing at night.
This help often comes from a mask ventilator, similar to devices used for sleep apnea. The mask fits over the nose, mouth, or both to support breathing during sleep.
Some people with advanced ALS choose to have a surgical opening made in their neck, called a tracheostomy. This allows a ventilator to connect directly to the windpipe, which may work better than a mask for some patients.
Breathing failure is the most common cause of death in ALS. Half of people with this condition die within 14 to 18 months of diagnosis. However, some individuals live 10 years or longer with ALS.
Speech Issues
Most ALS patients develop weakness in the muscles used for speaking. This typically begins with:
- Slower speech
- Occasional slurring of words
- Increasing difficulty speaking clearly
Over time, speech can become so affected that others cannot understand what the person is saying. When this happens, alternative communication methods and technologies become necessary.
Swallowing Problems
ALS can weaken the muscles needed for swallowing, which may lead to:
- Malnutrition: Unable to consume enough food.
- Dehydration: Difficulty drinking adequate fluids.
- Aspiration risk: Food, liquids, or saliva entering the lungs.
These swallowing difficulties increase the risk of pneumonia. A feeding tube is often recommended to ensure proper nutrition and hydration while reducing these risks.
Cognitive Changes
Some people with ALS experience problems with language and decision-making abilities. In certain cases, patients may eventually be diagnosed with frontotemporal dementia.
This is a specific form of dementia that affects the frontal and temporal portions of the brain. It can change how a person thinks, behaves, and communicates.
