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News: Being Born in Winter Increases Risk of Mental Health Disorders |
I guess this means Santa may be bi-polar! Enjoy!
Later -
Tater Scot
Posted from the news desk of ilovetater.com
Being Born in Winter Increases Risk of Mental Health Disorders
Scientists have a new theory for why people born in the winter months are more susceptible to certain mental illnesses. Researchers at Vanderbilt University manipulated the amount of light newborn mice received (article below). Some were exposed to a winter cycle of eight hours daylight and 16 hours of darkness, whereas others lived in a summer cycle of 16 hours of sun and eight hours of darkness. The scientists were then able to determine that when the mice got a littler older, the ones who had been introduced to the world on a summer cycle had a biological clock that wasn't effected by seasonal change. Those mice exposed to a winter-month light cycle experienced issues with their biological clocks. If this also holds true in humans, it could help explain why people born in winter are at higher risk for suffering from bipolar disorder, schizophrenia and seasonal affective disorder. However, until that is determined, we can't really recommend running your own summer-month simulations on any wintertime newborns.
Winter Birth May Affect Baby's Personality: Mouse Study
By Stephanie Pappas, LiveScience Senior Writer
posted: 05 December 2010 01:19 pm ET
Being born in winter versus summer may affect your biological clock in the long-term, according to a new study on mice.
The research, published online today (Dec. 5) in the journal Nature Neuroscience, found that mice born and weaned in a winter light cycle showed dramatic disruptions in their biological clocks later in life compared with baby mice born in summer light.
The finding is the first of its kind in mammals, and could explain why people born in the winter are at higher risk for mental health disorders including bipolar depression, schizophrenia andseasonal affective disorder.
Switching seasons"We know that the biological clock regulates mood in humans," study researcher Douglas McMahon, a biologist at Vanderbilt University in Tennessee, said in a statement. "If an imprinting mechanism similar to the one that we found in mice operates in humans, then it could not only have an effect on a number of behavioral disorders, but also have a more general effect on personality."
McMahon and his team began their experiment by raising baby mice from birth to weaning (about three weeks) in either "summer" light cycles of 16 hours of light and eight hours of dark or "winter" cycles of eight hours of light and 16 hours of dark. A third group experienced 12 hours of light and 12 hours of dark a day.
After they were weaned, the baby mice got shuffled into new light cycles. Half the winter mice stayed in a winter cycle, while half switched to a summer schedule. The summer mice were similarly split. The mice raised in equal periods of light and dark were split into three groups, one of which stayed on the 12-hour schedule, one of which joined the winter group, and one of which joined the summer subset.
After 28 days, all of the mice went into an environment of continuous darkness, eliminating the light cues that influence the biological clock. That way, researchers could determine the intrinsic biological cycle of each mouse.
"We were curious to see if light signals could shape the development of the biological clock," McMahon said.
As it turns out, they could. The summer-born mice behaved the same whether they stayed on the summer cycle or switched to winter: They ran at the time they once knew as dusk, continued for 10 hours, and then rested for 14 hours.
But the winter-born mice didn't react as well to the switch in seasons. Those that stayed in winter kept their 10-hours-on, 14-hours-off schedule. In contrast, those that switched to summer stayed active for an extra hour and a half.
Brains glowing green
The researchers used a strain of mice genetically engineered so their biological clock neurons would glow green when active. Using the glow, the researchers monitored an area called the suprachiasmatic nucleus (SCN), which sits in the middle of the brain and houses the biological clock.
The mice's behavior matched up to the activity in their SCN’s. In the summer-born mice, SCN activity peaked at dusk and continued for 10 hours, coinciding with the animals' running time. The winter-born mice that stayed in winter had an activity peak an hour after dusk that lasted 10 hours. In the winter-born mice that made the season switch, however, biological clock activity peaked two hours before dusk and continued for a whopping 12 hours.
The equal-light mice showed variations that fell between the two extremes, with 11-hour SCN activity regardless of the season they experienced post-weaning.
Whether humans might have similar responses to early-life light exposure isn't yet known, but McMahon said that the winter-born mice's exaggerated response to seasons changing was "strikingly similar" to human seasonal affective disorder.
Although research has shown that a winter birth raises the risk for certain mental disorders, there are many factors that could be at play, including exposure to flu or other seasonal diseases. The finding that light in infancy can play a role in later life may prove important for understanding how these disorders arise, the researchers wrote.
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