what causes adhd?

1. Resources for ADHD. As with all mental disorders, the exact cause of attention deficit disorder (ADHD) is unknown, so parents should not blame themselves for this problem. It is likely that many factors play a role in each case of ADHD, very little of which has to do with specific parenting or child rearing skills.

2. Attention-Deficit/Hyperactivity Disorder: Causes of ADHD

3. The exact causes of ADHD are not known with certainty.

   Experts do know that ADHD has a strong genetic component. In addition, they think that genes that control the levels of certain chemicals in the brain called neurotransmitters seem to be different in those with ADHD.
4. In some cases, though, there is no genetic link to ADHD, but other common behaviors,  such as smoking or drinking during pregnancy, as well as other obstetrical complications have been linked to ADHD in children.
   Babies with low birth weight may have an increased risk of ADHD. The same is true for children who have had head injuries, particularly an injury to the frontal lobe. Young children who are exposed to lead or other environmental toxins such as PCBs or pesticides early in life may also have a higher risk of ADHD.
   ADHD always begins in childhood. For some people, though, ADHD is not diagnosed until adulthood. That means adults who are newly diagnosed have actually had ADHD for years, and have had to endure symptoms as they've matured. In addition, research shows that between 30% and 70% of children with ADHD continue to have symptoms of the disorder when they become adults.

   What is the genetic connection to ADHD?

   ADHD tends to run in families. Studies have shown certain genetic characteristics that occur with high frequency in families where one or more family member has ADHD. Also, if one or both parents have ADHD, their children are more likely to develop the condition. And at least one-third of all fathers or mothers who had ADHD in their youth have children with ADHD.

   What brain changes occur with ADHD?

   Studies show that children and adults with ADHD tend to have abnormal functioning, or dysregulation, of certain brain chemicals known as neurotransmitters. There also tends to be abnormal functioning in the nerve pathways that regulate behavior. In addition, children with ADHD may have certain parts of the brain that are smaller or less active than they are in children who don't have ADHD.
   Recent studies show that the brain chemical, dopamine, may play a role in ADHD. Dopamine is an important chemical that carries signals between nerves in the brain. It is linked to many functions, including movement, sleep, mood, attention, and learning.
   One dopamine study focused on the genetics of ADHD -- specifically, on a particular variation of the DRD4 gene. This gene is associated with a dopamine receptor in the brain. What the study showed is that children with ADHD are more likely to have a certain variation of the DRD4 gene than children without ADHD. Interestingly, not all kids with ADHD in the study had the DRD4 gene variation. But those who did generally had higher IQ scores than other children with ADHD. Plus, the gene variation was most common in children whose ADHD improved over time.
   Another dopamine study involving adults with ADHD showed that adults with ADHD had a sluggish dopamine system. The study helped explain why stimulant ADHD medications such as Ritalin and Adderall are beneficial. Stimulant ADHD medications increase dopamine by strengthening the weak dopamine signals in the brain. That counters the decreased brain dopamine activity in adults with ADHD. In addition, drugs of abuse, like nicotine and cocaine, temporarily increase brain dopamine activity. So the study authors hypothesized that the decreased dopamine activity associated with ADHD may help explain why people with ADHD may have a greater risk of drug abuse.

As with all mental disorders, the exact cause of attention deficit disorder (ADHD) is unknown, so parents should not blame themselves for this problem. It is likely that many factors play a role in each case of ADHD, very little of which has to do with specific parenting or child rearing skills.

Inevitably, parents will ask themselves “What did I do to cause this?” or “How could I have prevented it?”, but most of the evidence points to genetic factors, environmental facts or brain damage.

Instead, parents should focus on how best to help their child with ADHD. Experts hope that someday, understanding the causes of the condition will lead to effective therapies, and evidence is building on the side of genetic causes for ADHD rather than elements of thehome environment. Certain aspects of a child’s environment may, however, affect the symptom severity of ADHD once it is established.

Possible causes of ADHD include:

Genes

ADHD has a strong genetic basis in the majority of cases, as a child with ADHD is four times as likely to have had a relative who was also diagnosed with attention deficit disorder. At the moment, researchers are investigating many different genes, particularly ones involved with the brain chemical dopamine. People with ADHD seem to have lower levels of dopamine in the brain.

Children with ADHD who carry a particular version of a certain gene have thinner brain tissue in the areas of the brain associated with attention. Research into this gene has showed that the difference are not permanent, however. As children with this gene grow up, their brains developed to a normal level of thickness and most ADHD symptoms subsided.

Nutrition and Food

Certain components of the diet, including food additives and sugar, can have clear effects on behavior. Some experts believe that food additives may exacerbate ADHD. And a popular belief is that refined sugar may be to blame for a range of abnormal behaviors.

However, the belief that sugar is one of the primary causes of attention deficit disorder does not have strong support in the research data. While some older studies did suggest a link, more recent research does not show a link between ADHD and sugar. While the jury is still out on whether sugar can contribute to ADHD symptoms, most experts now believe that the link is not a strong one. Simply removing sugar from a child’s diet is unlikely to significantly impact their ADHD behavior.

Some studies also suggest that a lack of omega-3 fatty acids is linked to ADHD symptoms. These fats are important for brain development and function, and there is plenty of evidence suggesting that a deficiency may contribute to developmental disorders including ADHD.Fish oil supplements appear to alleviate ADHD symptoms, at least in some children, and may even boost their performance at school.

The Environment

There may be a link between ADHD and maternal smoking. However,women who suffer from ADHD themselves are more likely to smoke, so a genetic explanation cannot be ruled out. Nevertheless, nicotine can cause hypoxia (lack of oxygen) in utero.

Lead exposure has also been suggested as a contributor to ADHD. Although paint no longer contains lead, it is possible that preschool children who live in older buildings may be exposed to toxic levels of lead from old paint or plumbing that has not been replaced.

Brain Injury

Brain injury may also be a cause of attention deficit disorder in some very small minority of children. This can come about following exposure to toxins or physical injury, either before or after birth. Experts say that head injuries can cause ADHD-like symptoms in previously unaffected people, perhaps due to frontal lobe damage.

Other Possible Causes

ADHD researchers are currently investigating the frontal lobes of the brain — the areas controlling problem-solving, planning, understanding other people’s behavior, and restraining our impulses.

The brain is divided into two halves, and the two frontal lobes communicate through a bundle of nerve fibers called the corpus callosum. These areas, and nearby brain cells, are being examined by ADHD researchers. Using brain imaging methods, the experts can get an idea of the location of the psychological deficits of ADHD.

A 2002 

study

 found that children with ADHD had 3-4 percent smaller brain volumes in all the brain regions measured. But children on ADHD medication had similar brain volumes to unaffected children, in some of the areas measured.

One big difference was the amount of “white matter” — long-distance connections between brain regions that normally become stronger as a child grows up. Children with ADHD who had never taken medication had an abnormally small volume of white matter.