Saturday, December 4, 2010

Perspectives on ADHD

I'm posting this collection of links here (rather than at IOC) because the diagnosis for ADHD in children still leans about 4 to 1 boys vs. girls. My sense is that this represents more of an effort to medicate boys and make them more docile, but there are other factors for this as well.

Partly, I think there has been an immense increase in the prevalence of ADHD as a result of poor diet (too much processed foods, too little healthy omega-3 fats) and because kids' toys today would make any brain hyperactive (far too many flashing lights, moving objects, colors, sounds).

Every cell in the brain is made from lipids (fats) and if kids do not get enough healthy fats, those cells do not develop properly. Saturated fats and especially trans fats produce less healthy cell structures. Kids need omega-3 fats from fish, walnuts, mother's milk (and mothers are generally deficient as well), and vegetable sources (flax seed/oil, hemp seed/oil).

Further, research shows that young kids develop better and learn better with one or two objects to focus on, repeatedly. But parents and toy manufacturers seem to believe that infants and young children have short attention spans, but that is because we have made them that way.

Anyway, ADHD is a hot topic for research, so here are some recent articles I have been collecting. There is considerable evidence developing that there is a genetic element to ADHD, although I suspect it is more epigenetic in origin.

Gene Linked To ADHD Allows Memory Task To Be Interrupted By Brain Regions Tied To Daydreaming

Neuroscientists at Georgetown University Medical Center (GUMC) say brain scans show that a gene nominally linked to attention deficit hyperactivity disorder (ADHD) leads to increased interference by brain regions associated with mind wandering during mental tasks.

Presented at the annual meeting of the Society for Neuroscience, these researchers believe their findings are the first to show, through brain scanning, the differences in brain network relationships between individuals with this particular form of gene and others with a different form.

"Our goal is to narrow down the function of candidate genes associated with ADHD, and in this study, we find this gene is tied to competition between brain networks. This could lead to increased inattention, but it likely has nothing to do with hyperactivity," says the study's lead author, Evan Gordon, a doctoral candidate in the Interdisciplinary Program in Neuroscience at GUMC. "This is just one gene, and it does not cause ADHD but likely contributes to it. The disorder is believed to be due to a myriad of genetic factors."

The gene in question is DAT1; its protein produces the dopamine transporter that helps regulate dopamine transmission between brain cells. The DAT1 gene comes in two alleles, or forms - DAT1 10 and DAT1 9. People who inherit two 10 alleles (10/10) are said to be at greater risk for developing ADHD than people who inherit 10/9 alleles. Rarely does someone inherit two 9 alleles, according to Gordon; he says, in fact, that the10 allele is slightly more common than the 9 allele.

The biological significance of inheriting a DAT1 10 allele is that the brain produces excess quantities of dopamine transporters, and that results in less dopamine signaling between neurons. Too many dopamine transporters quickly scoop up dopamine released by neurons, leaving fewer available to actually reach other neurons and pass on a signal. If there are fewer transporters, more dopamine stays in the synapse between neurons, triggering a reaction.

That is important, Gordon says, because dopamine is important for "gating" the transfer of information between brain regions - that is, allowing or preventing new information to come in. "The belief is that dopamine helps teach certain brain regions how and when to gate, and that 10/10 carriers are not gating as quickly or effectively as is possible."

That is exactly what the researchers found when they used functional MRI (fMRI) on a group of 38 participants. Half of the groups were 10/10 carriers and half were 10/9 carriers, and none of the participants were diagnosed with ADHD.

The researchers investigated the activity in two areas of the brain, the default mode network (DMN), which is associated with mind wandering or daydreaming and is active when the mind is at rest, and task-positive networks (TPNs), which are active during problem solving and other cognitive work. In this study, participants were asked to remember letters they saw on a screen inside the fMRI machine, and to recall them, thus activating TPNs.

Scanning demonstrated that in 10/10 carriers, the mind wandering areas tended to communicate with regions performing memory tasks more strongly than in did in 10/9 carriers. "Dopamine in the 10/10 carriers was not doing a good enough job in preventing the mind wandering regions from interfering with memory performance regions, resulting in less efficient cognition," Gordon says.

They also found no differences between genotype when the participants were at rest after their memory tasks.

"That tells us that the DAT1 genotype affects gating only when release of dopamine is high, such as during a memory task, and that less dopamine signaling leads to increased inattention," he says.

"Being a DAT1 10/10 carrier does not mean a person has ADHD; it is not a diagnostic marker," Gordon says. "It has been viewed as a contributing factor, and now we know one reason why."

The study was funded by the National Institute of Mental Health.

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ADHD On The Rise: 1 in 10 Kids Now Affected

The latest government figures show that 1 million more children in this country have been diagnosed with attention deficit hyperactivity disorder, or ADHD, in recent years.

A boy acts up in class.

A million more kids have been diagnosed with ADHD in recent years.

Nearly 1 in 10 children had been diagnosed with ADHD at some point in their lives, according a federal survey of parents conducted in 2007. That's up 22 percent from 2003, when the same survey found 1 in 13 children had received the diagnosis.


There's no clear answer.

The overall increase could reflect an increase in the disorder, or changes in the way it's diagnosed. But there are many more children who now carry the diagnosis and are candidates for care.

"Doctors and other health-care professionals have to be ready for the 1 million more children who will need to be managed," Centers for Disease Control and Prevention epidemiologist Susan Visser told Bloomberg. She's lead researcher on the report, which appears in the latest Morbidity and Mortality Weekly Report.

The biggest jumps were seen in children between 15 and 17 and among Hispanic or multiracial children. Researchers say the rise among Hispanic children may reflect better access to care, or greater cultural acceptance of the disorder.

But the disorder is still less common among Hispanics — about 6 percent — than among white or black children.

Finally, two-thirds of kids with a current diagnosis of ADHD were taking a medicine to treat it.

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ADHD: 12 Myths And Facts (PHOTOS)

Because attention deficit hyperactivity disorder (ADHD) symptoms -- inattention, impulsivity, and/or hyperactivity -- affect a child's ability to learn and get along with others, some people think an ADHD child's behavior is caused by a lack of discipline, a chaotic family life, or even too much TV.

In fact, research suggests that ADHD is largely a genetic disorder.

However, some environmental factors may play a role as well. Here, we separate fact from fiction about the causes of ADHD.

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Research does suggest a possible link between ADHD and pesticides.

A 2010 study in Pediatrics found that children with higher urine levels of organophosphate, a pesticide used on produce, had higher ADHD rates. Another 2010 study showed that women with higher urine levels of organophosphate were more likely to have a child with ADHD.

The studies suggest a possible link, but can't prove that pesticides cause ADHD. Marcy Rosenzweig Leavitt, PsyD, who works with ADHD patients in private practice in the Los Angeles area, recommends buying organic varieties of fruits and vegetables, especially those prone to high levels of pesticides (or scrubbing nonorganic produce before eating).
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Niccolo Leo Caldararo
San Francisco State University - Department of Anthropology

October 22, 2010

Cross-cultural research has placed in question the ADD/ADHD syndrome. Genetic studies have indicated some association of CNVs with ADD/ADHD but association does not equate with disease and the same CNVs appear in children without the disease questioning the genetic causality. Drugs for the treatment of ADD/ADHD may predispose children for depression and suicide. Dietary and behavioral research places new emphasis on cultural aspects of the etiology of high activity children. MRI studies of children’s brains as evidence for this syndrome are variable and inconsistent and may be artifacts of limited comparative data and analytical procedures.

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