Hyperthyroidism means the thyroid gland is overactive and produces more hormones than your body needs. Brain fog and other cognitive changes are potential complications of hyperthyroidism.

Brain fog isn’t a medical diagnosis but may describe a collection of symptoms, such as:

  • feeling “distant”
  • lack of concentration
  • forgetfulness
  • slowed cognitive processing
  • difficulty with problem solving

Brain fog can have many causes that range from not getting enough sleep to underlying medical conditions, including hyperthyroidism.

Some people with hyperthyroidism may continue to have brain fog for months to years, even after their underlying hormonal balance has been corrected.

Brain fog isn’t part of the diagnostic criteria for hyperthyroidism, so it’s not a formal symptom of the condition. But some people with hyperthyroidism do experience what could be described as brain fog.

Hyperthyroidism occurs in about 1.3% of people in the United States, but it’s often not severe enough to cause symptoms. Thyroid disease is 5 to 15 times more common in females than males.

Thyroid hormones are involved in several essential body functions, from growth to blood pressure and metabolism.

Overproduction of thyroid hormones may lead to many symptoms, including:

  • twitching
  • shallow breathing
  • fast heart rate
  • heat sensitivity or intolerance
  • diarrhea
  • loss of sex drive

Hyperthyroidism can also lead to different cognitive and mental changes, including symptoms often collectively referred to as “brain fog.”

For example, hyperthyroidism may manifest with symptoms like:

The most common cause of hyperthyroidism is the autoimmune disease Graves’ disease. Graves’ disease can manifest with cognitive impairment that persists for months to years, even after hyperthyroidism has been treated.

In a 2023 study, researchers found that mental fatigue and emotional distress were more common in people with Graves’ disease, even after 15 months of treatment, compared to people without Graves’ disease.

Also, brain fog often results from low sleep quality and duration. Studies have reported that as many as two-thirds of people with hyperthyroidism have trouble falling asleep, and some develop insomnia.

Can hypothyroidism also cause brain fog?

Hypothyroidism is the opposite of hyperthyroidism. It means the thyroid doesn’t produce enough thyroid hormones, which slows metabolism and may worsen other body functions.

Hypothyroidism can also potentially contribute to the development of brain fog. The inability to think seems to be high among people with low thyroid hormone.

Brain fog isn’t a medical diagnosis, so it has no set list of symptoms. The experience of brain fog may also vary in frequency, severity, and symptoms from person to person. These symptoms could include:

The best way to manage thyroid-related brain fog is to consult a healthcare professional to work on treatment options. Addressing the underlying cause of brain fog can help you get long-term results.

Also, you may benefit from making general lifestyle changes known to improve overall well-being, like:

Treatment for hyperthyroidism primarily aims to reduce thyroid hormone production.

How do you get rid of brain fog if you have thyroid dysfunction?

Brain fog may improve once your thyroid hormone levels return to regular ranges. Doctors can treat hyperthyroidism with medications, as it often requires long-term management.

What are the mental symptoms of hyperthyroidism?

Hyperthyroidism may manifest with mental symptoms like memory difficulties, trouble focusing, challenging problem solving, anxiety, and forgetfulness.

Is brain fog reversible?

Brain fog may improve once you address the underlying cause. If it’s related to hyperthyroidism, it may improve after treatment, but cognitive changes can sometimes persist for months to years after that.

Hyperthyroidism may cause symptoms that could contribute to “brain fog.” These symptoms include memory problems, cognitive impairment, anxiety, and slower processing speed.

Symptoms of hyperthyroidism often improve with treatment, but some people may continue to have symptoms for months to years after initiating therapy.

Working with a healthcare professional to identify and address the cause of brain fog is highly advised.