Ankylosing spondylitis (AS) is a form of inflammatory arthritis that primarily affects the spine. Although people often think about the physical symptoms, living with AS can also lead to what is known as brain fog.

Brain fog is not a medical condition. Instead, it is a phrase that people often use to describe symptoms related to thinking processes, recalling information, problem-solving, concentrating, or learning new things.

These symptoms are a common feature in chronic inflammatory conditions, such as AS, rheumatoid arthritis (RA), multiple sclerosis (MS), and other conditions.

A person can take steps to address brain fog, such as adopting preventive measures and following their AS treatment care plan.

People who are experiencing impairments in their memory, attention, or other cognitive skills may describe these symptoms conversationally as brain fog. Healthcare professionals may use more clinical terms, such as cognitive dysfunction or cognitive impairment, when referring to some of the same symptoms.

According to experts, cognitive dysfunction refers to a range of symptoms related to deficits in:

  • attention
  • auditory processing
  • verbal and nonverbal learning
  • short-term and working memory
  • motor functioning
  • visual processing
  • processing speed
  • problem-solving

In a 2020 study reviewing cognitive impairment in RA — which, like AS, is a type of inflammatory arthritis — researchers describe cognitive impairment as difficulty in:

  • remembering
  • making decisions
  • learning new things
  • concentrating
  • problem-solving

How AS affects the brain and central nervous system is still not clear. According to a 2020 study, researchers still do not know the prevalence of cognitive dysfunction among people with AS. They also suggest that it may be underreported.

Experts do not yet fully understand how conditions such as AS cause brain fog to occur. However, they do believe that brain fog may have a link to the chronic inflammation and pain associated with the condition.

Factors that may cause brain fog in people with AS may include the following:

Chronic inflammation

Conditions such as AS involve the immune system mistakenly attacking healthy cells in the body. When it does, it releases proteins known as cytokines, which cause inflammation to occur. Active cytokines send signals to a person’s brain, which may interfere with its expected functioning.

Chronic pain

Pain associated with AS can lead to a combination of fatigue and impaired cognitive ability.

The Spondylitis Association of America points out that the symptoms of AS can make it difficult for a person to sleep, leading to increased pain, stiffness, and fatigue, which then affect sleep further. This can lead to a cycle of sleeplessness and more severe symptoms.

Other experts note that chronic pain can cause the nervous system to become extra sensitive, which makes sleeping more difficult. The resulting fatigue can contribute to brain fog.

Use of corticosteroids

A 2021 study looking at cognitive decline in RA noted that people who use corticosteroids and have cardiovascular risk factors, such as high blood pressure, have an increased risk of developing cognitive impairment.

Doctors also use corticosteroids as a localized treatment for AS, which could indicate that people with AS and cardiovascular risk factors also have an increased risk of brain fog associated with steroid use.


Studies have shown that symptoms of AS can lead to depressive symptoms. Research has also linked depression to cognitive dysfunction. Therefore, a person with AS who develops depression may find that this depression contributes to their brain fog.

AS is not the only possible cause of brain fog. Several other health conditions and factors can contribute to brain fog, including:

  • chronic fatigue syndrome (CFS)
  • MS
  • lupus
  • fibromyalgia
  • Sjögren’s
  • thyroid issues
  • antidepressants
  • anemia
  • depression
  • pregnancy
  • menopause
  • chemotherapy
  • lack of sleep
  • lack of exercise
  • stress

People with AS who experience brain fog can take steps to help reduce its effects. The treatment for brain fog typically involves treating the underlying AS and making lifestyle adjustments that can help improve brain functioning.

Some tips and strategies to help reduce brain fog include:

  • focusing on the organization of thoughts, events, and so on to help keep a person alert throughout the day
  • using treatments for AS, including biologics, disease-modifying antirheumatic drugs (DMARDs), nonsteroidal anti-inflammatory drugs (NSAIDs), and other therapies
  • adopting good sleep hygiene practices
  • engaging in psychological therapies
  • exercising regularly

In addition, a person may find it helpful to take additional steps, such as:

  • recording when they experience brain fog to help look for patterns that they may be able to address
  • taking a deep breath and trying to relax when a cognitive issue is causing them frustration
  • practicing mindfulness, yoga, or other therapies to help relaxation
  • talking about medication options with a doctor
  • removing sources of light from the bedroom and making it cooler to promote sleep
  • keeping a consistent sleep schedule

People who continue to experience brain fog should talk with a doctor who may be able to make additional recommendations. The doctor might adjust the person’s prescription if they suspect that a current medication is not enough to control the symptoms or may be the cause of the brain fog.

AS can cause a person to experience problems with memory, thinking, concentrating, and other cognitive dysfunctions that people typically refer to as brain fog. The exact reasons for brain fog are not clear, but experts believe that chronic inflammation, pain, and some treatment side effects can all contribute. Depression may also play a role.

A person with AS can take several steps to reduce their brain fog. These include treating the underlying condition and making certain lifestyle changes, such as getting more sleep and exercising regularly.