Restless Legs and Attention Deficit in Adults and Kids

It may be surprising to learn that people with restless legs syndrome (RLS) may also experience problems with attention-deficit/hyperactivity disorder (ADHD).

Is there a single factor that links both conditions across all age groups?

What is ADHD?

ADHD is a disorder marked by:¹

• Struggles to pay attention
• Impulsiveness
• Hyperactivity

While it’s normal to experience some of these behaviors, it’s when they become severe and frequent, leading to interference in daily life, that they become problematic.

ADHD typically starts in childhood, with almost a third of all cases persisting into adulthood.²

People with ADHD experience a lot of sleep problems, including excessive daytime sleepiness, circadian disruptions, insomnia, and 2 related movement behaviors that impact sleep: RLS and PLMS (periodic limb movements of sleep).³

RLS and ADHD: Connecting the dots

RLS – and its symptomatic cousin PLMS – commonly affect people of all ages. Ultimately, low levels of blood iron (also called iron deficiency anemia or low serum ferritin) are a key root cause for both, regardless of age.

Meanwhile, though we know that ADHD affects people of all ages, it’s still generally associated with children. What’s interesting is that, consistent with RLS, a similar deficiency in iron levels has also been found to be consistent in people of all ages who have ADHD.

Adult research

Research published in Sleep calls out the fact that associations between RLS, PLMS, and ADHD have long been the province of pediatric sleep disorder research.⁴

These authors took their theories a step further, aiming to more closely examine RLS, PLMS, and ADHD in adults through a focus on iron deficiency. They found that in their large sample of adults with ADHD, RLS was diagnosed in 33 percent of subjects. (It’s important to note that RLS only occurs at a rate between 3 and 7.5 percent in the general population.)⁴

RLS was also associated with an earlier onset of ADHD – especially its hyperactive symptoms – and was linked to more severe ADHD symptoms over the lifespan. Meanwhile, iron deficiency was found in more than 35 percent of the same adult population with ADHD, with low serum ferritin characteristic in patients in the study who had RLS.⁴

Leg movements, in general, were also found to be more prominent in subjects with ADHD, though these were explained only by RLS and not PLMS.⁴

The bottom line: “Patients with ADHD and RLS had higher frequency of iron deficiency than other groups.”⁴

Pediatric research

The same study acknowledged that ADHD and RLS often present as comorbidities in children. In other words, they frequently occur together.⁴

Iron deficiency has long been indicated as a factor in both RLS and ADHD in children.⁵

But ADHD isn’t just a pediatric condition. The age of ADHD onset actually peaks at 2 times in the lives of those studied, the first peak happening around age 20, and the second in middle age.⁶

This makes ADHD not only a pediatric condition but an adult one, even if it begins during childhood. Even if ADHD is found to be problematic in the earlier part of the lifespan, challenges in diagnosing it at any stage of life can occur.

Ruling out mimic conditions

ADHD has several “mimic” conditions that need to be tested for and ruled in or out before treatment for these behavior problems can be started.⁷

As many as two-thirds of children with ADHD experience RLS-mimic conditions, the most common being:

• Pain conditions
• Habitual foot-tapping
• Positional discomfort

You can see how these conditions might make a parent or doctor suspect RLS.

Restless sleep disorder

Further complicating our understanding of ADHD and RLS is the addition of a new sleep disorder for children who have restless sleeping behaviors.

While over 80 percent of all children with ADHD complain of general restlessness during sleep, the new pediatric sleep disorder known as RSD (restless sleep disorder) may provide a different root cause, impacting nearly 10 percent of children with ADHD.⁸

Iron levels remain as the key explanation not only for RLS and ADHD, but RSD, too.

What can we learn from this?

A few things:^9-11

• Medical conditions which occur during childhood can and do persist into adulthood.
• Adults can and do experience ADHD even if it begins in childhood.
• RLS happens in people of all ages, but may be mistaken for another condition — RSD — in children.
• People with either RLS or ADHD have a 1 in 3 chance of developing the other condition.
• RLS, ADHD, and RSD share low levels of serum ferritin in common, but fortunately, all 3 can be treated with iron supplementation.
• Getting to the bottom of a restless sleep problem early in life is really important in order to ferret out its cause, its comorbidities, and the most effective long-term treatment