A new study has found that one-third of children who have attention deficit hyperactivity disorder (ADHD) were diagnosed with the disorder before they reached age of six. Researchers said the data has shown trends in relation to diagnosis of children with the neurobehavioral disorder. The ADHD rates have been increasing at nearly 5% a year for more than a decade and so far, no definitive test is there for diagnosis.

Parental reports indicate that more than 1 in 10 school-aged children (11%; 6.4 million children) in the United States have received a diagnosis of attention deficit/hyperactivity disorder (ADHD) from a health care provider

Parents were asked how old their child was “when you were first told by a doctor or other health care provider that he/she had ADHD?” The median age at ADHD diagnosis was 7 years, and about one in three children (30.7%) was diagnosed before age 6.

According to Dr. Susanna Visser, lead author of the report and an epidemiologist with the National Center on Birth Defects and Developmental Disabilities at the CDC, "Since many of the hallmark traits of ADHD can resemble typical behavior from a young child, it's important for the disorder to be properly recognized, diagnosed and treated to determine when that line is crossed".

However, Visser added that these findings provide information that physicians are increasingly using recommend practices for diagnosing children across the board.

It has been found by researchers that a combination of efforts by multiple sources close to the child and clinical evaluations are included in those recommendations. According to the report that was published on Thursday by the National Centers for Health Statistics, over half of children with ADHD were initially diagnosed by a primary care doctor.

According to Rachel Scheinfield, Ph.D., a school psychologist based in Atlanta, it has been shown in the research that there are higher chances that someone having ADHD could also suffer from another condition, like sleep disorder, learning disability, depression or anxiety.

In addition, a non-response bias analysis was performed, which suggested that, although the potential for bias cannot be ruled out, non-response bias in weighted estimates is likely smaller than sampling error.