22. Chronic Pain / Muscle Tension in ADHD

Author: Ulrich Brennecke
Review (March 2024): Waldemar Zdero, M.A. in Psychology
Completely revised: December 2024

Monoamines—specifically dopamine, norepinephrine, and serotonin—play a key role in pain regulation.¹

1. Chronic Pain and ADHD¶

People with ADHD often exhibit increased sensitivity to pain. High ADHD scores correlated with increased pain.^{23 4 5} Children with ADHD have a 45% increased risk of weekly pain. Hyperactivity/impulsivity was associated with a 133% increased risk of frequent pain, while inattention was associated with a 17% increased risk. Multiple pain complaints were more common among girls with hyperactivity than among boys with hyperactivity (51.4% versus 27.9%). 25% of girls with ADHD-C and 20% of boys with ADHD-C experienced weekly headaches and/or abdominal pain, compared with 11 to 13% of children without these symptoms (+127% to +53%).⁶

Suffer from chronic pain

• Children and adolescents with ADHD
  • between 66.9% and 29.1% (meta-analysis, k = 11)⁷
    • often musculoskeletal or multisegmental
    • Pain occurring at least once a week for more than 3 months
    • Treatment with stimulants reduced the rate of chronic pain
  • 20.8% (meta-analysis, k = 19, n = 1,043,878)⁸
    • Headaches and skeletal muscle pain: 25.7% (meta-analysis, k = 19, n = 1,043,878)⁸
    • Chronic pain and pain intensity in patients with ADHD are associated with muscular dysregulation.⁹
  • The prevalence rates of chronic pain among children and adolescents reported in a meta-analysis varied considerably:¹⁰
    • Headaches: 8% to 83%
    • Abdominal pain: 4% to 53%
    • Back pain: 14% to 24%
    • Skeletal muscle pain: 4% to 40%
    • multiple pain symptoms: 4% to 49%
    • Other types of pain: 5% to 88%.
  • 20%¹¹
• Adolescents and young adults
  • 66.5% (9-year longitudinal study, n = 263 with ADHD, n = 8,200 controls) vs. 44.5% among the controls¹²

Similar symptoms include increased sensitivity to stress and increased sensitivity to punishment. See “Emotional Dysregulation” for more information.

Girls experience chronic pain more frequently than boys, except for back pain and skeletal muscle pain (meta-analysis, k = 19, n = 1,043,878).⁸
Of 100 women with ADHD or ASD, 76% reported chronic pain.¹³ In ADHD, chronic widespread pain (CWP)—the main symptom of fibromyalgia—was nearly twice as common (39%) as in ASD.
The most commonly reported areas of the body where people experienced pain were

• lower back (47%)
• Neck (37%)
• Shoulder (35%)
• Head (32%, based on ADHD)
• Stomach (30%)
• Arms / Hands (30%)
• upper back (27%)
• Knee (27%)
• Hips / Thighs (18%)
• Calves / Feet (16%)
• Breast (4%)

ADHD is associated with an increased incidence of¹⁴

• Fibromyalgia¹⁵
• chronic lower back pain¹⁶
• idiopathic orofacial pain ¹⁷
• chronic abdominal pain¹³
• Burning-Mouth Syndrome
  • 92.2% of people with burning mouth syndrome had ADHD¹⁸

It is possible that chronic pain is more likely to be a cause of ADHD than ADHD is of chronic pain. There is significant genetic overlap between chronic pain and ADHD.¹⁹

Pain is associated with reduced tonic dopamine firing, which leads to increased phasic dopamine firing in the nucleus accumbens.²⁰ This is consistent with the model developed by Grace, which posits reduced tonic and increased phasic dopamine firing in ADHD. See also Tonic and Phasic Dopamine in Explanatory Models for ADHD in the section Dopamine In the chapter Neurological Aspects.
People with chronic pain exhibit reduced responsiveness within the mesolimbic dopamine system to significant stimuli, lower D2 receptor binding, and reduced presynaptic dopamine activity in the striatum at rest and following an acute pain stimulus.²¹ In animals, chronic pain leads to reduced c-Fos activation in the VTA, decreased total dopamine levels, and a reduction in D2 receptors in the striatum.²¹
Conversely, a reduction in dopamine in the brain caused by acute depletion of the dopamine precursors phenylalanine and tyrosine resulted in increased subjective pain sensitivity (the degree to which pain was perceived as unpleasant) without altering sensory pain perception.²²
In 6-OHDA mice, in which dopamine synthesis is chemically disrupted and which therefore serve as an animal model for ADHD, increased pain sensitivity was observed. This pain sensitivity was likely mediated by α- and β-adrenergic receptors as well as D2/D3 receptors. Atomoxetine²³, like MPH²⁴, was able to reduce the increased pain sensitivity associated with ADHD.
Stimulation of the substantia nigra, one of the brain’s two main sources of dopamine, alleviates pain by activating spinal cord neurons via dopaminergic signaling pathways.^{2526 27} Painful stimuli trigger a release of dopamine in the dorsolateral striatum, which correlates with the subjective perception of pain intensity. Similarly, the ventral striatum is clearly linked to the emotional dimension of the human pain process and to the anticipation of pain.²⁸
Increased sensitivity to pain correlated with certain dopaminergic gene variants (DAT1 and MAO-A, but not DRD4).²⁹
Increasing pain in children could be a precursor to restless legs syndrome. Serotonergic dysfunction, iron deficiency, and vitamin D deficiency could be common causes.³⁰ Both conditions and all three of the aforementioned causal pathways are closely linked to ADHD.

Among children with chronic pain (excluding headaches), the prevalence of ADHD was found to be 15 to 25 percent—a 2- to 5-fold increase (meta-analysis).⁷
72.5% of adults referred to a pain clinic for chronic pain and a probable somatic syndrome disorder met the diagnostic criteria for ADHD.³¹ Of 60 adults with chronic nonspecific lower back pain, 31.5% had ADHD.¹⁶
Psychiatric patients with chronic pain have a higher prevalence of ADHD than psychiatric patients without chronic pain.⁹
Among young women with ADHD and/or ASD, 76.6%¹³ and 75.9%, respectively, reported chronic pain, compared with 45.7% of young women without these conditions¹².
80% of the people with ADHD who were surveyed reported chronic pain.³²

A 15-year population-based study found that children with ADHD were significantly more likely to experience various types of pain prior to their ADHD diagnosis:³³

• Headaches (+16%)
• Earaches (+30%)
• Sore throat (+8%)
• Sprains and strains (+23%)
• more frequent use of pain relievers
  • Acetaminophen (+19%)
  • Ibuprofen (+37%)

A study found ADHD in 25 of 30 patients with refractory orofacial pain (83.3%; 20 of whom were women).³⁴
ADHD was associated with a 32% increased risk of migraine, while the risk of tension-type headaches remained unchanged.³⁵³⁶ Children with migraine had a 2.6-fold risk of ADHD, while the prevalence of migraine among children in general was 3.76%. Migraine correlated specifically with hyperactivity and impulsivity, but not with inattention.³⁷ Children with ADHD had a 2.6-fold risk of migraine, with the prevalence of migraine among children generally standing at 9.9% in this study.³⁶

In Parkinson’s disease, which is also characterized by a dopamine deficiency, 30 to 50 percent of people with ADHD suffer from increased pain sensitivity.³⁸ This can be alleviated with dopaminergic medication³⁹, such as levodopa or deep brain stimulation.⁴⁰
Conversely, in schizophrenia—which is associated with elevated dopamine levels—pain perception is reduced.⁴¹

The SHR ADHD animal model exhibits a dysregulated noradrenergic pain inhibition system.
In SHR, gabapentin was ineffective for neuropathic pain caused by segmental spinal nerve ligation, whereas duloxetine was effective.⁴² In Wistar rats, both gabapentin and duloxetine alleviated neuropathic pain. Unlike gabapentin, duloxetine increases spinal norepinephrine independently of locus coeruleus activation. Accordingly, norepinephrine reuptake inhibitors may be helpful for chronic pain associated with ADHD.

2. Axial Pain and ADHD¶

Chronic pain in patients with ADHD is characterized by widespread and axial pain that begins early in life. This “ADHD pain” differs qualitatively from chronic pain in patients without ADHD.⁹
Axial pain occurred in 86.6% of people with ADHD, in 50% of people without a diagnosis of ADHD, and in 21.4% of people who did not have subclinical ADHD either.
People with subclinical ADHD exhibited the same muscular dysregulation as people with ADHD.⁹
While ADHD is a predictor of “axial pain,” affective disorders, anxiety disorders, and personality disorders were not.⁹

The axial muscles are:

• Head and neck muscles
• Spinal muscles
• Other trunk muscles
• Pelvic floor muscles

Axial muscles regulate and control posture and are constantly working to maintain the inherently unstable upright position. Muscular dysregulation has significant effects in this area and could lead to high muscle tone, resulting in widespread pain and lower back pain.⁴³

• Erector spinae
• Latissimus dorsi
• Iliopsoas
  • connects the lumbar spine to the lower extremities
  • Tightness in the iliopsoas muscle can exacerbate lumbar lordosis and lower back pain⁴⁴

Gene variants associated with neck or shoulder pain causally increase the risk of ADHD.⁴⁵

3. Medications for Chronic Pain¶

See the following section Chronic Pain Comorbid with ADHD on the page Choosing a medication for ADHD or ADHD with comorbid conditions In the chapter Treatment

4. Increased Muscle Tension in ADHD¶

ADHD is often accompanied by increased muscle tension. However, this is not a manifestation of hyperactivity or a fundamental motor dysfunction. There are elite athletes with ADHD; it is unlikely that they suffer from any serious motor dysfunction. Nevertheless, increased muscle tension can also be observed in these individuals.

Muscle tension, particularly in the shoulder and neck area, occurs significantly more often in people with ADHD.
An orthopedic surgeon explained to us that during sleep, the muscles farther from the trunk (spine) relax first, while those closest to the spine relax last. These muscles require undisturbed deep sleep in order to relax. Accordingly, muscle tension could also be a consequence of the sleep disturbances associated with ADHD.
A study found that computer use and sleep problems were correlated with chronic shoulder and neck pain.⁴⁶

5. Pathways Leading to Chronic Pain, Increased Muscle Tone, and Fibromyalgia¶

According to Stray, motor disinhibition and increased muscle tone in ADHD are directly associated with dysregulation of the dopamine and norepinephrine systems.⁴⁷
This is consistent with the fact that, in ADHD, methylphenidate reduces increased muscle tone⁴⁸ and that a norepinephrine reuptake inhibitor (orphenadrine, Norflex®) acts as a skeletal muscle relaxant. Norepinephrine reuptake inhibitors are also used as ADHD medications (atomoxetine, viloxazine).

 

For more on this, see Chronic Pain and Muscle Tension in ADHD—Neurophysiological Correlates