In rare cases, children diagnosed with attention deficit hyperactivity disorder (ADHD) actually have a tumor that appears to cause symptoms similar to those of ADHD, according to a small new study.
The researchers evaluated 43 children with rare tumors of the adrenal gland, called pheochromocytomas and paragangliomas. (The adrenal glands are located near the kidneys, and produce adrenaline and other hormones.)
They found that nine of the children (21 percent) had been diagnosed with ADHD before doctors discovered their tumors. That's much higher than the usual rate of ADHD in children, which is 7.2 percent. What's more, after the tumors were removed, three out of the nine children no longer had symptoms of ADHD.
"Symptoms of anxiety and difficulty in concentration in these patients may have been related to their underlying [tumors]" but were not recognized as signs of these tumors, the researchers, from the National Institutes of Health, wrote in a paper published online May 12 in the journal Hormone and Metabolic Research. [Typical Toddler Behavior, or ADHD? 10 Ways to Tell]
Because high blood pressure is a common symptom of these tumors (and was seen in four out of the nine children diagnosed with ADHD), the researchers said that high blood pressure accompanying symptoms of ADHD may be a warning sign of these underlying tumors.
In children with high blood pressure and ADHD symptoms, "an evaluation to rule out [these tumors] is warranted prior to treatment with stimulant medications," they said.
Pheochromocytomas form inside the adrenal gland, whereas paragangliomas form outside the adrenal gland, according to the National Cancer Institute. But these tumors are very rare: It's estimated that pheochromocytomas occur in about 1 in 500,000 people, and paragangliomas occur in about 1 in 1 million people, according to the National Institutes of Health.
These tumors release compounds called catecholamines that stimulate the brain and spinal cord, the NIH said. It's possible that symptoms of these tumors may become worse when children take ADHD medications, the researchers said.