Food and Drug Administration and the Agency for Healthcare Research and Quality will undertake studies to determine whether people, both children and adults, taking ADHD drugs are at an increased risk of heart attacks.

It has been found that these drugs do lead to increase in heart rate and blood pressure but the tests will examine whether this increase was dangerous.

There have been reports of adverse cardiovascular events in adults and children with underlying risk factors who had been receiving drug treatment for ADHD, however it is not known if these events are causally related to treatment. This is exactly what the new tests are set to answer.

Last year, ADHD drugs makers were asked by the USFDA to include heart warnings on their labels due to an increased amount of heart attacks and strokes in both adults and pediatric patients taking them. Such warnings led to shares of Eli Lilly Co. falling by $1.15, or 2 percent, shares of Shire PLC by 47 cents and shares of Johnson and Johnson by 46 cents.