Why is attention deficit hyperactivity disorder (ADHD) so often associated with other conditions?
ADHD frequently occurs alongside other conditions such as dyslexia, dyspraxia, Tourette's syndrome and oppositional defiant disorder (ODD). There are several reasons why these linked conditions, or co-morbidities, are so often associated with ADHD.
Sometimes ADHD is a risk for behavioral problems such as conduct disorder or ODD. This is partly because the symptoms of ADHD can poison a child's relationships at home or with their peers, making the child more likely to become antisocial or depressed. Sometimes the ADHD is actually the result of another problem such as autism or a learning difficulty. ADHD may also have a common root in the brain with other developmental problems, such as dyslexia.
Co-morbid conditions can be hard to disentangle, and this is part of the reason that specialist assessment is advised for a child with ADHD.
Are genetics the only cause of ADHD?
International research has established that there is a strong genetically inherited contribution to ADHD. We know that parents, siblings and children of individuals with ADHD have a raised chance - perhaps as much as one in five - of having ADHD themselves. For identical twins that share all the same genes, if one has ADHD the other has a two out of three chance of also having it.
While genetic causes are important, it is also clear that environmental risk factors have a role to play. Environmental risks for ADHD were known before genetic influences were established. In 1902 Dr Still was one of the early paediatricians to describe hyperactive behaviour as one part of "disorders of moral control". He suggested this could be due to birth injury or trauma causing lack of oxygen to reach the brain.
The subsequent finding that genetic factors are the main reasons why ADHD tends to aggregate in families suggests that genes act to modify environmental risks. Environmental risk factors that have been identified so far include birth complications such as pre-maturity, low birth weight and exposure to alcohol and tobacco; parental and family factors such as early and severe neglect; and neurobiological risks such as closed head trauma and exposure to lead.
What treatment is available for ADHD?
There is no cure for ADHD, but there are a number of ways in which the condition can be managed. Treatments offered should take into account the severity of the ADHD and the impact it is having on the child's life. An early diagnosis can make a big difference.
Medications can help to control the core symptoms of ADHD and provide children with a 'window of opportunity' to be more focused and concentrate better. Doctors recommend that medication is prescribed in conjunction with specialised behaviour management advice for both parents and schools. Education about ADHD enables parents and teachers to give crucial practical and emotional support. Not all affected children need medication.
What medications are used to treat ADHD?
Methylphenidate, dexamfetamine and atomoxetine are the only medicines licensed in the UK to treat ADHD.
The medication most commonly used is methylphenidate. Its brand names include Ritalin, Equasym and Concerta. This stimulant drug provides short-lived improvements after each dose, but no permanent cure.
Dexamfetamine (brand names include Dexedrine) is also a stimulant and similar in its actions to methylphenidate. It sometimes works when methylphenidate does not.
Atomoxetine (which goes by the brand name of Strattera) is a non-stimulant drug and has only recently been licensed in the UK. Like methylphenidate it provides no permanent cure. Each dose provides a short-lived improvement which last approximately 24 hours.
There is a wide range of second line drugs that are sometimes used in specialist practice, including Clonidine, certain antidepressants and mood stabilisers.
Are the medications for ADHD addictive?
Dexamfetamine and methylphenidate are controlled drugs and can in theory be abused. However, the low and steady doses used to treat ADHD do not lead to dependence. Research suggests that children with ADHD are somewhat more likely to use illegal drugs, but that the risk actually falls if they are treated with stimulants.
Can a bad diet and too many additives cause ADHD?
There is no concrete evidence to suggest that ADHD is caused by bad diets or too many additives, but they might make a tendency worse. However, when food does contribute to a child's problems it is not exactly a 'bad diet'. Children can react badly to any of a range of foods, and it can be different for each individual child. Sometimes additives are the culprit but sometimes it is quite natural foods such as wheat flour, cow's milk or citrus fruit. Doctors are not sure how many children with ADHD are affected by reactions to food but most think it is a small minority.
Can fish oil or mineral supplements help to treat ADHD?
Science has not fully answered this one yet. There is some evidence emerging that fish oils can be helpful in treating ADHD, but as yet there is no large scale study to prove or dispute its effectiveness.
What's the difference between ADHD and ADD?
When diagnosing ADHD, doctors recognise three distinct types:
- Predominantly hyperactive-impulsive
- Predominantly inattentive
- Both hyperactive-impulsive and inattentive combined
The predominantly inattentive type is also called ADD (attention deficit disorder). ADD is less commonly diagnosed than ADHD, but more frequently in girls. Children with ADD are often seen as day-dreamers in a world of their own at the back of the classroom, and because their behaviour does not cause so much disruption, they are less likely to be referred for diagnosis.
In what ways are ADHD brains different from neuro-typical brains?
Studies using the latest high-tech brain imaging scans suggest that people with ADHD have significant differences in their brain size and structure.
The area of the brain that is mostly affected is the frontal lobes, which play an important role in a person's ability to stop and think before they act - to 'apply the brakes' - and also learn from past experience. Recent evidence suggests that these parts are less active than in ordinary people. Parts of the frontal lobes, the basal ganglia and the cerebellum are also a little smaller.
Does ADHD affect intelligence?
ADHD can affect people at any level of intelligence. It can make their IQ scores a little lower than they would otherwise be - probably because they do not concentrate on the tests as well.
Why do we hear so much about ADHD today? If it's a brain condition, shouldn't our ancestors have had it too?
Probably our ancestors did have it too. There is much more concern about it now but very little sign that the actual rate is going up. Perhaps ADHD was much less of a disadvantage in earlier periods of our evolution.
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