Thyroid disorders and ADHD have overlapping symptoms. Studies also suggest that there is an association between thyroid abnormalities and ADHD.

There are similarities between the symptoms of a thyroid disorder and the symptoms of ADHD. The two conditions also often co-occur.

While studies have found an association between ADHD and thyroid disorders, there is no substantial evidence supporting a causal link between the two.

This article explores the link between ADHD and thyroid disorders and their overlap. It also discusses ADHD and thyroid disorders and their causes, diagnosis, and treatment.

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Attention deficit hyperactivity disorder (ADHD) is one of the most common neurodevelopmental disorders in children. It is often first diagnosed in childhood, and it persists through adulthood. About 6.1 million Americans are ever diagnosed with the condition.

In ADHD, experts think a combination of genetic and environmental factors alters brain development and brain activity, affecting a person’s attention and behavior.

A person with ADHD may be overly active, act impulsively, and have difficulty focusing or concentrating. They may also have problems with planning, judgment, and problem-solving. These symptoms interfere with daily life.

Learn more about the signs and symptoms of ADHD here.

The thyroid gland plays a role in many vital functions in the body, including heart rate, breathing, rate of calorie burning, and heat production. It does this by creating two hormones: triiodothyronine (T3) and thyroxine (T4).

Thyroid disorder is an umbrella term for several conditions. It is a common disorder — around 20 million people in the United States have thyroid disease.

Hyperthyroidism causes the thyroid gland to make too many hormones, while hypothyroidism causes the thyroid gland not to make enough.

Learn more about common thyroid disorders.

Thyroid hormones are crucial for brain development and influence critical processes like nerve cell growth and myelination, which helps the brain transmit information. They also affect brain function throughout life and can potentially affect the regulation of motor, affective, and cognitive function.

Disruptions in brain function can affect a person’s cognition and behavior, which may lead to ADHD-like symptoms in typically developing children or worsening symptoms in those diagnosed with ADHD.

Thyroid hormone deficiency may severely affect a child’s brain in the womb and after birth, leading to intellectual deficits and neurological impairment.

A 2020 study found that maternal hypothyroidism increases the risk of ADHD diagnosis in the child, especially in preterm Hispanic boys. Even children exposed to mildly low thyroid levels (hypothyroxinemia) in early pregnancy showed more ADHD symptoms than children whose mothers had typical thyroid levels.

Another 2020 study found a positive association between fT3 (levels of free T3 hormone in the body not bound to special proteins) and the presence of ADHD symptoms in children. Children with hyperthyroidism have a risk ratio of 1.7 for ADHD compared with children without hyperthyroidism, according to a 2019 study.

Thyroid disorders and ADHD both have unique symptoms, some of which overlap. This section compares the symptoms of ADHD with two thyroid disorders.

Hypothyroidism happens when the thyroid gland does not produce enough thyroid hormone. When this happens, thyroid function declines, affecting bodily functions like metabolism, cognition, and sleep.

On the other hand, hyperthyroidism is caused by an overproduction of the thyroid hormone, leading to the overactivity of certain body functions.

ADHD HypothyroidismHyperthyroidism
difficulty paying attention and staying focused X
hyperactivity X
irritability X
lack of short-term working memory
insomnia X X
making careless mistakes
anxiety X
increased hyper-focusing
easy distractibility

Learn more about ADHD triggers.

Much evidence suggests that the two conditions are linked and frequently coexist. However, no studies confirm that one disorder directly causes or increases the risk of having the other condition.

The 2020 study mentioned above found a positive association between fT3 (levels of free T3 hormone in the body not bound to special proteins) and the presence of ADHD symptoms in children, which may suggest that fT3 influences the risk of ADHD.

While having one condition may increase the chance of having the other disorder, more research is needed to assess how high these chances are.

As the 2019 study above suggests, children with hyperthyroidism may have a risk ratio of 1.7 for ADHD compared with children without hyperthyroidism.

Here are some potential causes of ADHD and thyroid disorders.

What causes ADHD?

The exact cause of ADHD is still unclear, but recent studies link ADHD with genetic factors. Differences in brain anatomy and function, including neurotransmitter levels, may also play a role.

Some people may also be more at risk of ADHD. Researchers are investigating the following as possible causes or risk factors for ADHD:

What causes thyroid disorders?

Both hypothyroidism and hyperthyroidism can be caused by other diseases that impact the functioning of the thyroid gland. These include:

Thyroid disease and ADHD can be challenging to diagnose because their symptoms can also be seen in several other conditions.

For thyroid disease, specific tests can help determine if a thyroid problem is causing the symptoms. These may include:

There is no single test that can diagnose ADHD. A psychiatrist will determine if the person’s symptoms meet the criteria for ADHD based on the Diagnostic and Statistical Manual of Mental Disorders, 5th edition (DSM-5).

Psychiatric professionals will check for symptoms of inattention, hyperactivity, and impulsivity for at least 6 months in more than two settings, such as school, work, or home. The specialist will also explore whether other conditions may be causing the symptoms.

Learn more about the ADHD diagnosis process here.

Thyroid disorders have several symptoms that may also be seen in people with ADHD, making a misdiagnosis possible.

It is also possible for a person living with a thyroid disorder to be correctly diagnosed with ADHD but have their thyroid disorder go unrecognized and undiagnosed.

Learn more about ADHD misdiagnosis here.

The treatment for thyroid disorders depends on their type and symptoms. Doctors give individuals with hypothyroidism thyroid hormone pills that provide the body with the hormones necessary to function properly. This treatment is often lifelong.

The treatment for hyperthyroidism depends on its symptoms, cause, and the person’s preference. Treatments include:

There are many treatment options for ADHD. What works best depends on the child and their family. Standard treatments include:

Early detection and management are essential for both conditions. A person who suspects that they or their child has a thyroid disorder or ADHD should seek the help of a doctor who can diagnose and rule out other conditions that can be mistaken for thyroid disease or ADHD.

It is also essential for a person to mention if their symptoms are interfering with their daily life or if their current treatment isn’t helping. A doctor may switch them to another treatment or add one to the person’s current regimen.

All forms of thyroid diseases and ADHD tend to persist throughout a person’s life but can be treated with medication, support, and education.

A person with ADHD and thyroid disease can live a normal, productive life. However, most would require lifelong management and treatment.