A study from the University of Maryland found that thyroid hormone may play a role in the hyperactive and impulse symptoms of children with attention deficit hyperactivity disorder (ADHD).
The lead investigators, Dr. Peter Hauser and Dr. Bruce Weintraub, had previously determined that children with thyroid hormone resistance have a strong association with ADHD. For this reason, they conducted their study on 77 patients with thyroid hormone resistance and their unaffected family members.
In thyroid hormone resistance levels of TSH remain elevated or inappropriately normal in the presence of high levels of T4 and T3. The researchers found that high levels of T4 and T3 correlated with symptoms of hyperactivity and impulsitivity symptoms in patients with thyroid hormone resistance. The TSH level didn’t show any correlation.
In family members without thyroid hormone resistance, the TSH and T4 levels did not correlate with symptoms of hyperactivity/impulsivity. However, in family members without thyroid hormone resistance, high levels of T3 correlated with symptoms of hyperactivity/impulsitivity but not with symptoms of inattention.
While the study doesn’t show a causal role for elevated thyroid hormone levels in ADHD, it does show that thyroid hormones may provide a physiologic basis for the symptoms of inattention and the symptoms of hyperactivity.
Further studies show that children with hyperthyroidism are likely to also have symptoms of anxiety along with hyperactivity and impulsitivity symptoms. Anxiety is not a symptom seen in childen with ADHD.
Resource:
Hyperactivity Linked to Thyroid Hormone, Science Daily, March, 1997.