People with ADHD are at an increased risk of developing an addiction problem, with tobacco and cannabis the most likely offenders, experts have warned.

ADHD (attention deficit hyperactivity disorder) is a behavioural disorder, the main symptoms of which include inattention, impulsivity and hyperactivity. Those affected show poor concentration, are often unable to complete tasks, day dream a lot, are distracted easily, act without thinking and can suffer temper tantrums.

Hyperactive symptoms can include restlessness and not being able to remain seated, such as during meals. In adults, this can manifest itself through excessive talking and feelings of being overwhelmed.

According to experts attending the International Congress of Dual Pathology in Spain recently, those with ADHD are more vulnerable to addiction and as many as one in four people with addictions have undiagnosed ADHD.

"There is a clear relationship between ADHD and disorders caused by the use of substances. This pathology is a clear and significant risk factor for the development of an addictive disorder. In fact, any given patient with attention deficit has twice the possibilities of developing an addiction than an individual who does not suffer from such a disorder," commented Dr José Martínez-Raga, a psychiatrist at the Doctor Peset University Hospital in Valencia.

Experts also pointed out that many adults with the condition remain undiagnosed.

"ADHD has been considered exclusively as an infant disorder. However, research has shown that not only it is the most frequent neuro-biological disorder in infancy, but also a chronic development disorder that persists into adulthood in more than half of patients, if it is not adequately treated. Only 25% of adults with ADHD are diagnosed during childhood," explained Dr Nestor Szerman, president of the Spanish Dual Pathology Society.

The congress was told that adolescence is a time when many people start experimenting with drugs and if there is a disorder, such as ADHD, already present, ‘there is an increased vulnerability'.

Tobacco and cannabis are the two substances most frequently used by teenagers and adults with ADHD, with some undiagnosed people using these drugs as a type of self-medication to tackle the discomfort they feel.

The experts noted that cannabis can complicate things further because it has been linked to problems with attention, concentration and memory. This can make an ADHD diagnosis even more difficult.

However the congress was also told that if children are properly treated for ADHD, this reduces the risk of them going on to develop a substance addiction. This in turn reduces their risk of doing poorly at school or suffering social and medical problems in general.