John Scott reviews recent research.

Diagnostic complications
The diagnosis of ADHD can be complicated by the fact that a number of other conditions and factors can give rise to ADHD-like symptoms, and this may even lead to misdiagnosis.

Sleep and breathing disorders such as snoring and apnea have been shown to be linked to ADHD symptoms. (Click here for report)

Brain damage, such as that caused by toxins (lead from paint) or cerebral palsy, can produce very similar symptoms to ADHD. People with ADHD can also suffer from mental illness, depression, anxiety or bi-polar disorder, which can themselves produce symptoms such as inattention, hyperactivity and problems with impulse control. Dyslexia and other learning difficulties may accompany ADHD, but may also be misdiagnosed as ADHD.

The boredom and inattention seen in those with ADHD can also be demonstrated by highly intelligent children, although ADHD can affect children with any level of IQ.

Food and chemical allergies and sensitivities can cause ADHD-like symptoms in anyone, whether or not they have ADHD. They can also exacerbate the symptoms of those who do have ADHD, who may be sensitive to particular substances.

Certain parenting styles, as well as abuse, may cause otherwise normal children to react with behaviours similar to those of ADHD. It is also true that few parents are equipped to deal properly with an ADHD child and many need professional help in order to avoid making the problem worse.

Brain dysfunction found
There is increasing evidence that ADHD is a genetic neurobiological disease, and two new studies have added to this by demonstrating a link between ADHD and changes in production of the brain chemical dopamine.

In the first study, researchers found that about one-quarter to one-fifth of children with ADHD have a variant of the dopamine receptor gene (DRD4) which may help cause the behavioural condition by producing thinner tissue in areas of the brain that control attention. Strangely, however, children who have the risk gene also tend to get better in the long term, eventually regaining healthy tissue thickness in the affected brain region - a fact that may explain ADHD's tendency to improve with age.

In a second study, scientists found that ADHD is associated with lowered dopamine production and that the drug Ritalin is able to help some children with ADHD by increasing the brain's production of this chemical. The researchers found that the reduction in dopamine was associated with typical symptoms of inattention, which may explain why many people with ADHD tend to abuse drugs such as nicotine, cocaine and methamphetamine, all of which increase dopamine activity in the brain.
Sources: Archives of General Psychiatry, August 2007; vol 64: pp 921-931and August 2007; vol 64: pp 932-940.
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Ritalin may affect the developing brain
Ritalin (methylphenidate) is a stimulant drug similar to amphetamine and cocaine, which has a paradoxical calming effect in children with ADHD.

One of the first studies to probe the effects of Ritalin on the neurochemistry of the developing brain has examined the effect of the drug on the brains of rats. It found that Ritalin caused long-term changes in the developing brain, altering areas related to executive functioning, addiction and appetite, social relationships and stress. The relative doses used on the rats were at the very high end of what a human child might be prescribed, and the animals' neurochemistry had largely resolved back to the pre-treatment state three months after they stopped receiving Ritalin, but the researchers nevertheless expressed their concern about long-term use.

It is possible that Ritalin might leave more lasting changes, especially if treatment were to continue for years, and also that chronic use of the drug might alter brain chemistry and behaviour well into adulthood.

The findings certainly support the notion that this drug therapy may be best used over a relatively short period, rather than for years, as currently happens, and supplemented or replaced with behavioural therapy.
Source Journal of Neuroscience, 2007; 27: 7196-7207.
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Ritalin stunts growth
A major US study has recently reported that, after three years on Ritalin, children are about an inch shorter and 4.4 pounds lighter than their peers. Previously, researchers had thought that any short-term stunting of growth would be made up by a hypothesised 'growth spurt' that would occur with continued treatment. However, this study found no evidence of such a growth spurt, and whether affected children eventually grow to normal size remains uncertain.

Another widely accepted theory was that ADHD itself stunts children's growth but, in a surprise finding, the study found that children with ADHD who do not take stimulant drugs are actually much larger than those without ADHD. And these untreated children continue to grow much faster than those taking the drugs. This study suggests that growth monitoring should be standard practice for children on these medications.

The team involved in this study also compared the effect of Ritalin relative to behavioural treatment alone and found that, while the effect of the drug was substantial at 14 months, it had reduced somewhat by 24 months and, by 36 months, the ADHD drug had no relative advantage over behavioural treatment.

Source Journal of the American Academy of Child and Adolescent Psychiatry, August 2007; vol 46: pp 1014-1026.
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Non-medicinal treatment successful
Non-medicinal interventions can be very effective in preventing the behavioural and academic problems associated with ADHD, according to an ambitious five-year US study.

Focusing on children aged three to five, who had shown significant symptoms of ADHD, the study evaluated the effectiveness of early intervention techniques in helping children decrease defiant behaviour and aggression, while improving academic and social skills.

The interventions used included highly individualised programmes that relied on the positive reinforcement of good behaviour and the modification of home and school environments, such as altering tasks and activities in the classroom, to better accommodate children with the disorder.

Using a variety of early intervention strategies, parents reported, on average, a 17% decrease in aggression and a 21% improvement in their children’s social skills. Teachers saw similarly strong results in the classroom: there was a 28% improvement in both categories and early literacy skills improved three-fold.

Whereas medication only addresses the symptoms of ADHD, this study demonstrates that non-medicinal strategies can be used to address behavioural and academic issues before they become more problematic at infant school.

Some paediatricians have questioned whether it is possible to accurately identify children with ADHD at such an early age, given the similarity between ADHD symptoms and normal behaviours in young children. However, this study suggests that with careful assessment, affected children can be accurately identified and helped by appropriate behavioural interventions.
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Training the ADHD brain may boost behaviour
Training the brains of children with ADHD, using a technique called neuro-feedback, can improve attention and concentration, and reduce hyperactivity and impulsivity in some children, according to a team of Swiss and German researchers.

Thirty children, aged nine to 13, were divided into two groups, one of which received neurofeedback training - a high-tech non-invasive therapy, which, it is claimed, can alter brainwave patterns to achieve a more normal brainwave profile.

The second group were given group training, using techniques based on cognitive behaviour therapy, to provide training in social skills, self-awareness and self-management.

Half the children in the neurofeedback group successfully learned to regulate their brain activity and showed greater improvements in controlling hyperactivity and impulsivity, as quantified by parents and teachers, who noted no such improvements in the children who had group training.

Neurofeedback training could therefore be a viable alternative for a subgroup of children with ADHD who respond particularly well to this type of treatment.
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Australia vows to reduce drug use for ADHD
The Western Australian government has recently announced its aim to cut its use of amphetamines for ADHD.

Under a multi-million-dollar programme, teams of professionals will be appointed that will include psychiatrists, paediatricians, clinical psychologists, clinical nurses, speech pathologists, occupational therapists and social workers.

It is hoped that the new approach to be used by these professionals will ensure that stimulant medication is not used as the first line of treatment, but reserved for severe cases.

Vaccination, autism and ADHD
While medical and governmental authorities continue to deny vehemently any possible connection between childhood vaccination and neurological disorders such as autism and ADHD, research continues to appear that points to just such a correlation.

A new US survey, which shows an unequivocal link, was carried out for Generation Rescue, a group for parents of children with neurological disorders, that is dedicated to examining the causes of, and biomedical treatments for autism, Asperger's syndrome and ADHD.

The survey, which was conducted by a national market research firm, involved the parents of more than 17,000 children, aged 4-17, in nine counties in California and Oregon.

Among more than 9,000 boys aged 4-17, the survey found that vaccinated boys were two and a half times more likely to have a neurological disorder compared with their unvaccinated peers. Vaccinated boys were also over three times more likely to have ADHD, and over one and a half times more likely to have autism.

For older vaccinated boys in the 11-17 age range, the results were even more pronounced. Vaccinated boys were more than four times as likely to have ADHD, and more than twice as likely to have autism.

Rates of ADHD and autism in the US climbed alarmingly between 1983 and 2007, when the recommended vaccine schedule more than tripled, and ADHD currently affects one in 13 children in the US.

First published in 2007

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