Ankylosing spondylitis (AS) can have an onset at any age. However, the symptoms typically begin in late adolescence or early adulthood. Most people receive an AS diagnosis before age 45.

AS is a type of inflammatory arthritis that primarily affects the spine. Common early symptoms include pain and stiffness in the lower back and at the top of the buttocks. The symptoms come on gradually over several weeks to months.

As AS progresses, people often experience pain in other areas of the body, such as the neck or shoulders. However, this progression can take many years or decades.

This article discusses the AS age of onset, its diagnosis, and treatment.

A man with AS in physical therapy. He is holding himself up on two bars while a therapist helps.Share on Pinterest
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According to the Spondylitis Association of America, people typically develop AS between 17 and 45 years of age. Most people develop AS in their 20s and 30s. In a 2022 study, the average age of onset worldwide was 26.

However, AS can affect people of all ages.

Juvenile ankylosing spondylosis (JAS) is a form of AS that affects young children and adolescents. Doctors do not know the exact cause, but they know it has strong links with a gene known as HLA-B27.

Around 80–90% of children with JAS have this gene. However, many people who have the gene never develop JAS symptoms.

Experts think that children with the HLA-B27 gene may develop JAS in response to a trigger, such as a virus, bacteria, or another factor.

Yes, AS often progresses as a person ages, although this can take decades to occur. Early treatment with appropriate medications and lifestyle changes may help reduce or stop AS progression.

Around 1 in 4 people living with AS notice that their symptoms progress over time. Certain factors appear to influence disease progression, including:

  • being male
  • having joint damage at the time of diagnosis
  • having active disease
  • having increased levels of inflammatory markers that indicate spinal damage

A 2021 study also suggests that an individual’s genetics and family history affect disease progression.

As AS progresses, the inflammation from the spine and vertebrae can spread to other joints, including the hips, shoulders, and ribs. It can also affect the tendons and ligaments connecting bones and muscles.

If severe, chronic inflammation can cause the vertebrae of the spine to fuse together. As a result, a person may have decreased range of motion and changes in posture.

The inflammation AS causes can also spread to organs, such as the heart and digestive system. Around 6–14% of people with AS also have inflammatory bowel disease, which is significantly more common than in the general population. Up to half of people with AS also have osteoporosis.

It is rare for AS to begin later in life, although not impossible. If a person has lower back pain in late adulthood, there may be another cause.

The risk of most other forms of arthritis, such as osteoarthritis, increases with age. There are also many other conditions that can cause back pain or stiffness, such as:

  • injury
  • osteoporosis
  • nerve compression
  • degenerative disc disease
  • disc herniation
  • spinal stenosis
  • sacroiliac joint dysfunction
  • facet joint injury
  • infection

There is no single test to diagnose AS. Instead, doctors use a person’s medical history, family history, and a physical exam.

During the exam, a doctor will check for signs of pain, tenderness, and swelling in the spine, pelvis, and hips. They may also order imaging tests, such as X-rays, MRI, or CT scans of the pelvis and spine, to look for damage.

Early diagnosis is important for AS because beginning treatment as soon as possible can help to prevent long-term joint damage.

There is no cure for AS. Treatment aims to reduce inflammation and pain, stop disease progression, and improve quality of life. This may involve a combination of medications and physical therapy to maintain strength and flexibility.

Medications for AS include nonsteroidal anti-inflammatory drugs (NSAIDs) to reduce pain and inflammation, and biologics, such as disease-modifying antirheumatic drugs, to help control the disease.

Although doctors do not commonly use them for spinal disease in AS, corticosteroids can sometimes help with knee or shoulder problems.

Learn more about treatments and medications for AS here.

AS does not directly affect life expectancy. However, some complications that have links to AS, such as cardiovascular disease, do increase the risk of heart attacks and stroke.

An older study found that people with AS have a 35% higher risk of death from heart attack and a 60% increased risk of dying from stroke than the general population.

People may ask a doctor about what they can do to lower their risk of these complications.

Learn more about AS complications here.

Ankylosing spondylitis (AS) is a type of inflammatory arthritis that affects the spine and other joints. Most people develop symptoms before the age of 45.

Although AS can progress, causing the spinal vertebrae to fuse, early diagnosis and treatment can help prevent long-term joint damage and preserve mobility.

There is no cure for AS, but medications, exercise, and physical therapy can help reduce symptoms.