Sunlight and ADHD


  • Health
  • Sunday, 26 May 2013

RESEARCHERS are interested in exploring how sunlight, sleep and screens (like those on computers and TVs) may affect those with attention-deficit/hyperactivity disorder (ADHD), says Dr L. Eugene Arnold, a child psychiatrist and ADHD expert at the Ohio State University Wexner Medical Center’s Nisonger Center, US.

ADHD is a neurodevelopmental disorder characterised by developmentally inappropriate degrees of inattentiveness, impulsivity and hyperactivity. Although ADHD is the most common neuropsychiatric/behavioural disorder of childhood and has been extensively studied in young children, it occurs in all age groups.

An estimated 13 million men, women and children in the United States fit the diagnosis for ADHD or one of its subcategories, says Arnold, who is professor emeritus of psychiatry at The Ohio State University, where he was formerly director of the division of child and adolescent psychiatry and vice chair of psychiatry.

Arnold collaborated with Dr Martijn Arns of the Netherlands on a recent study published in Biological Psychiatry that sheds new light on the increasing rates of prevalence of ADHD. This study found that “sunny” regions with high solar intensity, such as the U.S. states of California, Arizona, and Colorado, and countries like Spain and Mexico, have lower prevalence of ADHD.

An apparent protective effect of sunlight accounted for 34-57% of the variation in ADHD prevalence. The authors speculate that this may be related to sunlight’s effects on preventing the disturbance of circadian rhythm or “biological clock”.

Researchers from Utrecht University, Research Institute Brainclinics, Leiden University, and Ohio State University published their work suggesting a possible preventive effect of sunlight on ADHD.

Examining ADHD prevalence rates per US state and solar intensity maps, the authors observed a striking geographical coincidence between low ADHD prevalence and high solar intensity.

Solar intensity is a measure of how much sunlight a specific area receives, which is often used for calculating how much energy solar panels will generate.

States with less sunlight had higher rates of patients diagnosed with ADHD, as much as 10-12%. But in states where there is more sunshine, there are fewer cases.

“Those states have about, say, 5 or 6% rate of ADHD. So, it’s about a two-to-one ratio,” says Arnold. “There are many possible explanations. For example, with more sunlight, maybe kids get out more to play and get more of the exercise that, increasingly, we know is good for brain function.”

But sunlight may not be the only issue. Arnold says there may also be a link to sleep, since those with ADHD have the same traits as those who are sleep-deprived.

“There’s a correlation with things like irritability, impulsiveness, inattentiveness – which are core symptoms of ADHD,” says Arnold. “And what’s robbing them of sleep may be their computer and TV screens. They emit a blue light that could be disrupting melatonin, which is the hormone that helps regulate sleep. Children’s duration of sleep has decreased over the past decade or two since the introduction of those electronic devices.”

The authors hypothesise that this delayed circadian rhythm and difficulty falling asleep may be caused by increased evening use of modern media, such as tablet computers and smart phones, especially with social media increasing the exposure to such blue-light sources during the evening.

“By preventing the onset of melatonin, blue light delays the onset of sleep and that disrupts the sleep-wake cycle,” says Arnold. “More studies are needed to better understand these potential connections with ADHD.”

In an interesting twist, experts say the rates of ADHD may be lower in states with brighter sunshine because sunlight actually overrides the blue-light effect that comes from TV and computer screens.

“The main value of this particular study is that it opens up new vistas, new things to be investigated that maybe we hadn’t quite thought about before,” says Arnold. – HealthNewsDigest.com

NEARLY 20% of kidneys that are recovered from deceased donors in the US are refused for transplant due to factors ranging from scarring in small blood vessels of the kidney’s filtering units to the organ going too long without blood or oxygen.

But, what if instead of being discarded, these organs could be “recycled” to help solve the critical shortage of donor organs?

Researchers at Wake Forest Baptist Medical Center and colleagues, reporting in the journal Biomaterials, found that human kidneys discarded for transplant can potentially serve as a natural “scaffolding material” for manufacturing replacement organs in the lab using regenerative medicine techniques.

According to the authors, more than 2,600 donor kidneys are discarded each year in the US. “With about 100,000 people in the US awaiting kidney transplants, it is devastating when an organ is donated but cannot be used,” said Dr Giuseppe Orlando, lead author, a Wake Forest Baptist transplant surgeon and regenerative medicine researcher. “These discarded organs may represent an ideal platform for investigations aimed at manufacturing kidneys for transplant.”

The research involved pumping a mild detergent through kidneys that were refused for transplant. The goal of the process, called decellularisation, is to remove all cells – leaving only the organ structure or “skeleton”, known in regenerative medicine terms as a scaffold.

Ultimately, the patient’s own cells could be placed in this scaffold, creating a customised organ that the patient theoretically would not reject.

In fact, an analysis of the decellularised organs revealed that antigens likely to cause an immune response were removed in the cleaning process. “This finding has significant implications,” said Orlando. “It indicates that transplantation of such customised kidneys could be performed without the need for anti-rejection therapy.

“In addition, these kidneys maintain their innate three-dimensional architecture, their basic biochemistry, as well as their vessel network system. When we tested their ability to be transplanted (in pigs), these kidneys were able to maintain blood pressure, suggesting a functional and resilient vasculature.”

While the project is in its infancy, the idea represents a potential solution to the extreme shortage of donor kidneys. According to the authors, the probability in the US of receiving a kidney transplant within five years of being added to the waiting list is less than 35%, and people age 60 or older who are placed on the waiting list only have a 50% chance of ever receiving a kidney.

The science of regenerative medicine has already had success in engineering skin, cartilage, bladders, urine tubes, trachea and blood vessels in the lab that were successfully implanted in patients. Most of these structures were able to receive oxygen and nutrients from nearby tissues until they developed their own blood vessel supply.

However, more complex organs such as the kidney, liver, heart and pancreas are larger with dense cellular networks and must have their own oxygen supply to survive. The need for a blood supply is why scientists are exploring the possibility of using donor organs and “seeding” them with a patient’s own cells.

As the research continues, the scientists will need to assess whether discarded organs with certain defects can be used to benefit patients.

For example, some kidneys are rejected because of fibrosis (scarring) in the tiny vessels throughout the organ. Can these organs be recycled? Orlando said that time will tell but that early clinical data suggests that fibrotic lesions are reversible and that the human body has the ability to remodel kidney fibrosis and restore normal anatomy. – HealthNewsDigest.com


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