• Duchenne muscular dystrophy (DMD) causes worsening symptoms that increasingly affect a person’s life.
• Some symptoms, such as muscle weakness, are usually present early on in the disease and progress over time.
• Other symptoms, such as heart disease and breathing problems, become more likely to develop with age.

Duchenne muscular dystrophy is a genetic disorder that progresses — or gets worse as a person gets older. When a child with DMD is first born, they may not have any immediate signs. However, symptoms may eventually appear and then continue to worsen after a diagnosis.

The Five Stages of DMD

Researchers have identified stages that help describe what DMD may look like at different points during a person’s life. Although progression may look different for different people, those with DMD generally move through five stages:

1. Diagnosis — During infancy and early childhood years, a child with DMD may start experiencing initial DMD symptoms, although many children don’t display any signs.
2. Early ambulatory — Children are usually diagnosed with DMD between the ages of 3 and 6, although they may not display many symptoms at this time.
3. Late ambulatory — During the late childhood and teen years, a child with DMD will often start to experience more significant problems with muscle weakness and tiredness.
4. Early nonambulatory — Most people with DMD are somewhat nonambulatory (unable to walk) by the time they turn 12, and symptoms worsen in the teen and young adult years.
5. Late nonambulatory — Adults with DMD need continued care to monitor for ongoing health issues.

Work with your or your loved one’s health care provider to learn more about what to expect at each stage. As DMD progresses, you or your loved one may experience different symptoms and your medical care plan may change.

What Does DMD Progression Look Like?

Signs of progression may look different compared to the initial symptoms that lead to a diagnosis of DMD. If you have a child living with DMD and they start experiencing any new symptoms, talk to their pediatric care team, as this may be a sign that the condition is worsening.

1. Worsened Muscle Weakness

A decrease in muscle strength is the main symptom of DMD — it occurs for nearly everyone with this neuromuscular disease. Weakness is often present early on for infants with DMD, but it tends to get worse over time as the condition affects more skeletal muscles (the muscles attached to bones that help you move around).

For those with DMD, muscle weakness tends to affect muscles in a certain order. Muscle cells in the hips, pelvis, and shoulders tend to be impacted first. Later on in the disease course, weakness affects muscle fibers in the abdomen, back, lower arms, and thighs.

Initially, DMD may lead to frequent falls or to an abnormal gait, such as waddling or walking on the toes, and difficulty standing from a squatting position. They may walk their hands up their legs to stand upright, a maneuver called Gowers’ sign.

Sometime during the preteen, teen, or young adult years, their progressive muscle weakness will typically become severe enough that moving around becomes difficult and they lose their ability to climb stairs. Walking aids such as a scooter or leg braces can often help people with DMD get around more easily. Wheelchair use becomes common by the time children with DMD reach 12 years of age.

2. Muscle Pain

More than half of teens living with DMD experience persistent or ongoing pain in their muscles. These aches can make it harder to move around and get in the way of being social. Pain can also take away from a child’s ability to be independent, worsen their well-being, and negatively impact their mood.

Muscle pain is more likely to be a problem as DMD progresses. As a child moves into the late nonambulatory stage of DMD, they tend to experience pain more often in additional parts of their body.

3. Tiredness

It may take some time for this DMD symptom to appear — some children with the condition can move around and play in the same way as their friends without DMD. However, fatigue can worsen as they get older.

Feelings of tiredness are a common part of DMD. One study found that about 4 out of 10 people with DMD experienced fatigue. This symptom can affect your loved one’s quality of life, making them feel worse. Fatigue may occur because of the ongoing muscle damage that is a characteristic part of the disease. It may also be linked to mental health issues like depression or sleep problems, which are common in people with DMD.

4. Spinal Abnormalities

Young children with DMD may start walking with their chest pushed forward. Later on, as DMD worsens, back issues may grow more severe. Children with the condition may develop scoliosis (sideways curving of the spine) or lordosis, also referred to as swayback — a condition in which the lower spine curves too far inward.

5. Broken Bones

DMD can weaken the bones. Over time, children with the condition are more likely to experience broken bones. By the time they turn 6, about 4 percent of those with DMD have broken a bone, while this number jumps to 60 percent by the time children reach the age of 15. This may occur partly because kids with DMD often have vitamin D deficiencies, and the body needs this nutrient to absorb calcium (a mineral important for bone strength).

Some of the most common places where fractures occur include the back and hips. Doctors often recommend that people with DMD undergo regular spinal X-rays to look for small cracks in the spine.

6. Heart Problems

DMD commonly affects the heart. Many people with the condition start experiencing cardiomyopathy (disease of the heart muscle) when they are in their late teen years. By the age of 18, nearly everyone with DMD has this heart problem.

Cardiomyopathy is a weakened heart muscle, which can prevent the organ from pumping enough blood around the body. People with DMD may also experience abnormal heart rhythms called arrhythmias, which may cause the heart to beat too quickly, too slowly, or irregularly.

Health experts recommend tests to measure heart function starting when a person is first diagnosed with DMD. Then, people with DMD should get follow-up tests once every year or two, or more often if heart symptoms are present. This can help your health care team recommend appropriate treatments as your child’s DMD and related heart problems progress.

7. Breathing Difficulties

Many people with DMD have breathing problems as well as symptoms of too little oxygen, such as tiredness, headaches, and nightmares.

Respiratory symptoms arise when muscles in the chest become too weak to work properly. This can prevent a child from being able to effectively cough out germs or mucus. Mucus can block the airways, making it hard to take a deep breath. Parts of a child’s lungs or airways can also collapse. These issues can make it easier to develop respiratory infections like pneumonia.

Breathing issues typically occur at night early on in the course of DMD. However, as the disease progresses, it can lead to shallow breathing during the day as well. Respiratory failure (an inability to breathe in enough oxygen) may make it harder to think clearly and can stunt a person’s growth.

Some health experts recommend that children with DMD undergo regular testing to look for respiratory issues starting at the age of 5 or 6. When your doctor monitors your child’s breathing abilities over time, they can quickly diagnose and treat any new respiratory symptoms as DMD progresses.

8. Digestive Problems

Weakened muscles in the abdomen may affect swallowing and digestion. Normally, muscles near the stomach and intestines help push food through the digestive tract. During DMD, however, the muscles don’t work well enough to keep food moving at a normal rate. This condition, called dysmotility, may lead to symptoms like constipation or diarrhea.

9. Urinary Symptoms

In a study from PLoS One, researchers estimated that urinary incontinence affects 15 percent to 37 percent of men with DMD or Becker muscular dystrophy, another form of muscular dystrophy. This symptom occurs when urine leaks out when you don’t mean it to. Urinary incontinence can impact your emotional health, get in the way of travel, and make it hard to want to spend time around other people.

10. Symptoms Related to Thinking, Learning, and Behavior

As children with DMD age, they may increasingly need extra assistance in school or at work. They may experience problems related to cognition (thinking), such as struggling to concentrate or multitask. DMD can also make it hard to control emotions, and people with this rare disease may experience emotional outbursts. Finally, the older children with DMD get, the more apparent it may be that DMD is impacting their memory, making it harder to learn new things or develop new skills.

Treating DMD Progression

Talk to your or your loved one’s doctor if you notice new symptoms that could be related to DMD. They can help determine which treatments may be able to relieve your child’s symptoms and improve their well-being while living with DMD.

Talk With Others Who Understand

On myDMDcenter, people with Duchenne muscular dystrophy and their loved ones come together to gain a new understanding of DMD and share their stories with others who understand life with DMD.

Do you or a loved one live with DMD? What signs and symptoms have you experienced? Share more in the comments below.