Initial signs of ALS can vary from muscle twitches or stiffness to difficulty swallowing. But this is a progressive neurological disease that ultimately makes movement impossible. It is also known as Lou Gehrig’s disease.
This article will discuss the age at which this condition usually strikes, what the earliest signs are likely to be, common risk factors, causes, how ALS progresses, and when to reach out for care.
ALS Age of Onset
While you can get ALS at any age, it usually affects those between 55 and 75. But one genetic form of ALS has been known to affect children as young as 4 years old. This particular form of ALS is caused by the gene SPTLC1, which affects the body’s fat production.1
Early Signs and Symptoms of ALS
The first symptoms of ALS may be subtle, and you may excuse or ignore them. Some of these early symptoms include the following:1
- Cramps in muscles
- Muscles stiffness or tightness
- Muscle jerking or contracting
- Chewing issues or problems swallowing
- Persistent and progressive difficulty speaking clearly, including slurring words for no reason
You may suddenly have trouble buttoning your coat or signing your name. Problems can start in different parts of the body.
Bulbar onset is a type of ALS that causes problems with swallowing or speech. Frequently tripping or running awkwardly are signs of limb onset ALS.1
Causes and Risk Factors
Unfortunately, most of the time, ALS occurs spontaneously without any apparent links to family history or genetic factors to explain it.1 This is called sporadic ALS.
But in up to 10% of cases, there can be a family connection. With familial ALS, there’s a 50% likelihood that each child will inherit the mutation (change in genetic material) that may lead to the disease.1
People who served in the military are somewhat more likely to develop ALS than those who haven’t served. The Department of Veterans Affairs recognizes ALS as a service-related condition.1
This may be due to the exposure to toxins released during warfare, environmental factors, or continually participating in highly strenuous activities.1 The latter may explain why professional athletes like National Football League players may be predisposed to this condition.2 ALS is commonly called Lou Gehrig’s disease after the professional baseball player.
Genetics may play a role in ALS. In about two-thirds of cases in which ALS runs in families, a gene mutation can be identified. In fact, more than 25 genes may contribute to ALS.
Some of the key genes that may be implicated include the following:3
- The SOD1 gene mutation was the first detected (in 1993). It is thought to account for up to 20% of familial ALS cases and up to 2% of cases of sporadic ALS. Only one copy of the gene (from one parent) is enough to cause ALS when inherited. While the exact mechanism remains unclear, researchers think that the mutation causes the protein it produces to form clumps in motor neurons and astrocytes, leading to the death of these cells and ALS.
- C9orf72, first discovered in 2011, is the most common genetic source of ALS, responsible for up to 40% of ALS cases that run in families and 7% of sporadic ones (cases that occur without a family history). Just one copy of the gene is needed to cause ALS.
- NEK1 is a genetic mutation that accounts for 3% of all ALS cases. This is present in both instances that run in families as well as those that occur spontaneously.
- TDP43 is found in 4% of familial cases and 1% of sporadic ones. Mutations in the TDP43 gene can cause the protein it produces to clump in motor neurons.
- FUS (fused in sarcoma) was discovered in 2008. Just one copy of this dominant gene is needed to cause ALS. This causes 5% of familial cases and 1% of sporadic ones. This resembles TDP43, and likely plays a similar role in causing ALS.
- KIF5A (kinesin family member 5A) was first detected in 2018. Just one copy of this gene is needed to cause ALS. Those with this mutation tend to survive longer than others with ALS, living on average for about 10 years after diagnosis.
While ALS can, unfortunately, affect anyone, some groups are more likely than others to develop the condition, including the following:4
- White males over age 60, without a family history of ALS, are most prone to the condition.
- In the United States, Blacks are less likely than Whites to be diagnosed with ALS.
- About 5% to 10% of people with ALS have a family history of this condition.
- Higher concentrations of ALS appear in the U.S. Midwest and Northeast, areas where there is a high proportion of Whites.
- The Western region of the United States has the lowest proportion of ALS cases, possibly due to the diversity of the population.
- The slightly higher proportion of men vs. women wanes as people age.1
Note that Verywell Health prefers to use inclusive terminology. But when citing health authorities and research, the terms relating to gender and sex from those sources are used.
The environment that you live in also plays an important role. Here are some factors that are suspected to potentially trigger ALS:5
- Beta-methylamino-l-alanine (BMAA), a naturally produced neurotoxin7
- Exposure to metals, radiation, solvents, and other toxins5
- Viruses (but none yet identified)9
- Military service10
- Intense exercise as part of your occupation11
How ALS Progresses
ALS may start with minor issues such as difficulty fastening buttons or turning on the ignition in your car. This may seem perplexing at first. As the disease worsens, so do problems such as speaking, swallowing, moving, or breathing.
With time, weight loss may also become a problem.
ALS mainly affects physical functions. Most people with ALS maintain their reasoning abilities and understanding of how the condition affects them.1 A small percentage of people with ALS may also have difficulties with language or making decisions.