Sleep Deprivation Influences Drug Use in Teens' Social Networks, Study Finds

ScienceDaily (Mar. 20, 2010) — Recent studies have shown that behaviors such as happiness, obesity, smoking and altruism are "contagious" within adult social networks. In other words, your behavior not only influences your friends, but also their friends and so on. Researchers at the University of California, San Diego and Harvard University have taken this a step farther and found that the spread of one behavior in social networks -- in this case, poor sleep patterns -- influences the spread of another behavior, adolescent drug use.


The study, led by Sara C. Mednick, PhD, assistant professor of psychiatry at the University of California, San Diego School of Medicine and the VA San Diego Healthcare System, will be published March 19 in PLoS ONE.
"This is our first investigation of the spread of illegal drug use in social networks," said Mednick. "We believe it is also the first study in any age population on the spread of sleep behaviors through social networks."
Using social network data from the National Longitudinal Study of Adolescent Health, Mednick and her colleagues James H. Fowler, UCSD Department of Political Science and Nicholas A. Christakis, Harvard Medical School, mapped the social networks of 8,349 adolescents in grades 7 through 12. They found clusters of poor sleep behavior and marijuana use that extended up to four degrees of separation (to one's friends' friends' friends' friends) in the social network.

Another novel network effect that they discovered was that teens who are at the center of the network are at greater risk of poor sleep, which in turn means they are more likely to use marijuana -- putting them at the crossroads of two behaviors increases a teenager's vulnerability.
Contrary to the general assumption that drug use has a negative effect on sleep, the researchers also found that sleep loss is likely to drive adolescents to use drugs -- the less they sleep the more likely their friends are to sleep poorly and use marijuana.
"Our behaviors are connected to each other and we need to start thinking about how one behavior affects our lives on many levels," said Mednick. "Therefore, when parents, schools and law enforcement want to look for ways to influence one outcome, such as drug use, our research suggests that targeting another behavior, like sleep, may have a positive influence. They should be promoting healthy sleep habits that eliminate behaviors which interfere with sleep: take the TV out of the child's bedroom, limit computer and phone usage to daytime and early evening hours, and promote napping."
The research was funded by the National Institute of Mental Health, National Institute on Aging and National Institute of Child Health and Human Development.
Sciencedaily.com

Start running and watch your brain grow, say scientists

The health benefits of a regular run have long been known, but scientists have never understood the curious ability of exercise to boost brain power.
Now researchers think they have the answer. Neuroscientists at Cambridge University have shown that running stimulates the brain to grow fresh grey matter and it has a big impact on mental ability.
A few days of running led to the growth of hundreds of thousands of new brain cells that improved the ability to recall memories without confusing them, a skill that is crucial for learning and other cognitive tasks, researchers said.
The new brain cells appeared in a region that is linked to the formation and recollection of memories. The work reveals why jogging and other aerobic exercise can improve memory and learning, and potentially slow down the deterioration of mental ability that happens with old age.
"We know exercise can be good for healthy brain function, but this work provides us with a mechanism for the effect," said Timothy Bussey, a behavioural neuroscientist at Cambridge and a senior author on the study. The research builds on a growing body of work that suggests exercise plays a vital role in keeping the brain healthy by encouraging the growth of fresh brain cells.
Previous studies have shown that "neurogenesis" is limited in people with depression, but that their symptoms can improve if they exercise regularly. Some antidepressant drugs work by encouraging the growth of new brain cells.
Scientists are unsure why exercise triggers the growth of grey matter, but it may be linked to increased blood flow or higher levels of hormones that are released while exercising. Exercise might also reduce stress, which inhibits new brain cells through a hormone called cortisol.
The Cambridge researchers joined forces with colleagues at the US National Institute on Ageing in Maryland to investigate the effect of running.
They studied two groups of mice, one of which had unlimited access to a running wheel throughout. The other mice formed a control group. In a brief training session, the mice were put in front of a computer screen that displayed two identical squares side by side. If they nudged the one on the left with their nose they received a sugar pellet reward. If they nudged the one on the right, they got nothing.
After training the mice went on to do the memory test. The more they nudged the correct square, the better they scored. At the start of the test, the squares were 30cm apart, but got closer and closer together until they were almost touching. This part of the experiment was designed to test how good the mice were at separating two very similar memories. The human equivalent could be remembering what a person had for dinner yesterday and the day before, or where they parked on different trips to the supermarket.
The running mice clocked up an average of 15 miles (24km) a day. Their scores in the memory test were nearly twice as high as those of the control group. The greatest improvement was seen in the later stages of the experiment, when the two squares were so close they nearly touched, according to a report in the Proceedings of the National Academy of Sciences.
"At this stage of the experiment, the two memories the mice are forming of the squares are very similar. It is when they have to distinguish between the two that these new brain cells really make a difference," Bussey said.
The sedentary mice got steadily worse at the test because their memories became too similar to separate.
The scientists also tried to wrongfoot the mice by switching the square that produced a food reward. The running mice were quicker to catch on when scientists changed them around.
Brain tissue taken from the rodents showed that the running mice had grown fresh grey matter during the experiment. Tissue samples from the dentate gyrus part of the brain revealed on average 6,000 new brain cells in every cubic millimetre. The dentate gyrus is part of the hippocampus, one of the few regions of the adult brain that can grow fresh brain cells.
The Guardian

Eye test may detect Alzheimer's

A simple eye test might be able to detect Alzheimer's and other diseases before symptoms develop, according to UK scientists.

The technique uses fluorescent markers which attach to dying cells which can be seen in the retina and give an early indication of brain cell death.

The research has been carried out on mice, but human trials are planned.

Scientists from University College London hope this could lead to a high street opticians test for the disease.

The research, which is published in the journal, Cell Death and Disease, could enable scientists to overcome the difficulty of investigating what is happening inside the brains of those with Alzheimer's.

They currently have to rely on expensive MRI scans or post-mortems.

Fluorescent dye

This new technique enables scientists to track the progress of brain disease by looking at dying cells in the retina.

The cells show up as green dots because they absorb the fluorescent dye.

"These findings have the potential to transform the way we diagnose Alzheimer's"

Rebecca Wood, Alzheimer's Research Trust

The research has so far been carried out on mice, but the team is optimistic that the technique can be translated to humans.

Professor Francesca Coredeiro, lead author from University College London Institute of Ophthalmology said: "Few people realise that the retina is a direct, albeit thin, extension of the brain.

"It is entirely possible that in the future a visit to a high-street optician to check on your eyesight will also be a check on the state of your brain."

"I hope that screening for Alzheimer's will be available on the high street within five years."

She said the research could help scientists to see how the disease is progressing by comparing retinal cell death a few weeks apart.

"Currently, the biggest obstacle to research into new treatments for neurodegenerative diseases is the lack of a technique where the brain's response to new treatments can be directly assessed - this technique could potentially help overcome that."

Patient trials

The first patient trials to assess the technique for the eye disease will begin later this year.

Rebecca Wood, Chief Executive of the Alzheimer's Research Trust, said: "These findings have the potential to transform the way we diagnose Alzheimer's, greatly enhancing efforts to develop new treatments and cures.

"If we spot Alzheimer's in its earliest stages, we may be able to treat and reverse the progression of the disease as new treatments are developed.

"Dementia scientists currently lack a way of assessing the brain's responses to new treatments in real time; this technique may help overcome that obstacle.

"700,000 people in the UK live with Alzheimer's and other dementias, and that number is set to double within a generation unless scientists make rapid progress in their race for a cure."

Dr Susanne Sorensen from the Alzheimer's Society also welcomed the research, but stressed much more research was needed to see if the technique could indeed be used to diagnose the disease, or monitor the effects of drugs under development. BBC Health