Almost 300 prescriptions were issued for those over 50 years old, up from 119 prescriptions three years earlier. Current year figures were on track to hit almost 400 prescriptions, up from 119 in 2013.
Researchers said an increasing awareness of the disorder - and a willingness to prescribe drugs as a primary option - were behind the growth in prescriptions.
Dr Julia Rucklidge, professor of clinical psychology at the University of Canterbury, said medical professionals and the public had a greater awareness of the disorder.
She said some parents whose children were diagnosed noticed they had symptoms themselves.
"Now psychiatrists are far more accepting - and it took a long time for this to happen - that ADHD can exist in adulthood because of long-term studies that were done," Dr Rucklidge said.
She said almost 1000 extra prescriptions of medication were distributed in Northland in 2016 compared with 2013, a 26 per cent increase in three years.
The most common brand names for ADHD drugs were Ritalin, Rubifen and Concerta - all containing the active ingredient methylphenidate hydrochloride.
However, Dr Rucklidge said research showed the long-term efficacy of ADHD medication was dubious, and the Government must consider whether rapidly increasing prescription rates were appropriate, particularly for young people.
"It should probably be more cautiously considered. There are other treatments ... It is an easy way out."
She said research showed parents of children taking ADHD medication were less likely to implement behavioural management strategies.
"If you're accepting that a medication is necessary for your child to behave well, then you are more likely to attribute their behaviour to a biological cause," she said.
"This means parents may neglect implementing behavioural management strategies because that would be suggesting there are environmental contributing factors."
University of Otago childhood ADHD researcher Dr Dione Healey said significant prescription increases in the past few years were surprising, given the medical community had been well aware of ADHD for the past 10 or 15 years.
She said the latest international guidelines lowered the threshold for ADHD to be diagnosed, which may have driven the increase in prescriptions.
Dr Healey also urged caution against medicating as a panacea, but said other methods of treatment, including teacher aides and behavioural management, were resource-heavy.
