Ankylosing spondylitis (AS) is a form of inflammatory arthritis that primarily affects the spine. AS can lead to cognitive symptoms some people call brain fog, including forgetfulness, dissociation, and trouble with decision-making.

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

These symptoms are common in chronic inflammatory conditions, such as AS. However, a person can take steps to address brain fog, such as adopting preventive measures and following their AS treatment plan.

This article explains the link between AS and brain fog, including symptoms, treatment options, and when to contact a doctor.

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People experiencing impairments in memory, attention, or other cognitive skills — which relate to thinking — 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 a 2022 study, first-person descriptions of brain fog may include:

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

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

How AS affects the brain and central nervous system is still unclear. According to a 2020 study, researchers still do not know the prevalence of cognitive dysfunction among people with AS, and those with AS may underreport this symptom.

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

Factors that may cause brain fog in people with AS may include the below.

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 typical functioning.

Chronic pain

Pain relating to AS can lead to fatigue and impaired cognitive ability.

The Spondylitis Association of America states 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 looked at cognitive decline in RA. The researchers noted that those who used corticosteroids and have cardiovascular risk factors, such as high blood pressure, have an increased risk of cognitive impairment.

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


A 2019 cross-sectional study suggests that symptoms of AS can lead to depressive symptoms.

Research associates depression with certain cognitive disorders, such as difficulty with memory, processing speeds, and executive function. These may persist during the remission of other depressive symptoms.

Therefore, a person with AS who develops depression may find that depression contributes to their brain fog.

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

Some tips and strategies to help reduce brain fog may include:

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 with AS who continue to experience brain fog despite making the above changes need to consult a doctor who may be able to make additional recommendations.

The doctor might adjust the person’s treatment plan if they suspect that their 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 call 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. Mental health conditions such as 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.