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  Columbia scientists say that thinning layers of neurons in the brain’s cortex, shown here, may be a precursor to depression.
Getting to the bottom of depression

Some people with depression suffer because a structural abnormality in the brain prevents them from interpreting social cues from other people. That’s the implication of a groundbreaking study published by Columbia psychiatric researchers Myrna Weissman and Bradley Peterson in the Proceedings of the National Academy of Sciences this spring.

Weissman and Peterson conducted one of the largest-ever imaging studies of people at risk for developing depression. Using functional magnetic resonance imaging (fMRI), they examined the brains of 131 people, aged 6 to 54. At the time of the study, none of their subjects had ever experienced depression, but about half were at high risk for developing depression based on their family history of the illness. The researchers excluded from their study people who already had depression because they did not want to observe in people’s brains structural abnormalities that could have resulted from the illness, but rather they sought to identify structural abnormalities that signaled their predisposition.

Indeed, the study revealed something remarkable about the brains of people whose parents and grandparents had depression: their brain cortex, which is the outermost layer of the organ, was 28 percent thinner on the right hemisphere than is normal. That’s a drastic reduction of brain tissue, on par with what has been observed previously in persons with Alzheimer’s disease and schizophrenia. “We almost didn’t believe it,” says Peterson. “But we checked and rechecked all of our data, and we looked for all possible alternative explanations.”

Additional tests showed that the subjects with a thinned right cortex were less able to pay attention to, interpret, and remember social cues.

Weissman and Peterson hypothesize that a thinning of the right cortex is a precursor to depression only when it occurs in tandem with other structural irregularities. Their data suggest, for instance, that a thinning of the left cortex also might have to occur for depression to take root. In other cases, a thinning of the right cortex, and its ensuing cognitive difficulties, might lead to schizophrenia, attention-deficit hyperactivity disorder (ADHD), or other psychiatric problems, according to previous studies.

Weissman and Peterson say that their research, by identifying what appears to be a common anatomical basis for such disorders, points toward new treatment strategies for depression. “For example, either behavioral therapies that aim to improve attention and memory or stimulant medications currently used for ADHD may surface as possible treatments for people who have familial depression and this pattern of cortical thinning,” says Peterson.

“This is entirely speculative at this point, but it’s a logical hypothesis to test based on the findings from this study.”

 


 
 
 
A conventional silicon-based solar cell.
 
Solar solution

Commercially available solar panels today convert only about 15 percent of the energy captured from sunlight into electricity. The remaining energy gets lost in a variety of ways. For instance, silicon, the semiconductor found in most solar cells that compose the panels, naturally absorbs some energy.

The U.S. Department of Energy recently awarded Columbia researchers a $16 million, five-year grant to invent more-efficient solar cells. Chemist Louis Brus, physicist Tony Hein, and electrical engineer James Yardley will lead a team of about 15 professors in an attempt to create cells that transmit electricity not through silicon but through novel manmade materials such as graphene. Graphene is created by arranging carbon atoms in a crystalline latticework that’s one-atom thick; it is the hardest material ever tested, which gives it very low electrical resistance. The Columbia professors hope to develop technology that could be used eventually to generate electricity for a wide range of uses, from automobiles to homes to laptop computers.

Through the grant, Columbia becomes home to 1 of 46 new DOE-funded Energy Frontier Research Centers that will pursue advanced scientific research on clean-energy technology. “Several other centers will be trying to improve existing solar cell technology, but we’re really trying to invent something completely different,” says Brus. “Every technology has a standard limit of efficiency, beyond which tinkering does not improve it all that much. And our project is looking for that revolutionary advance that could double or triple the efficiency of these things.”

New York governor David A. Paterson ’77CC has offered to seek up to an additional $500,000 to support the project. The New York State Energy Research and Development Authority has already said it will contribute $250,000, and the New York State Foundation for Science, Technology and Innovation has offered access to the supercomputers at the Brookhaven National Laboratory and Rensselaer Polytechnic Institute.

The Columbia team plans to collaborate with researchers at the University of Minnesota, the University of Arkansas, and Purdue University. To read more, visit http://news.columbia.edu/research/1531.



 
 
  Thousands of people in northeastern Kenya in 2007 were displaced by floods that had immediately followed a drought.
Desperate moves

They’ll flee Laos, Thailand, Cambodia, and Vietnam, where rising seas could inundate half of all farmland in the region. They’ll move out of southern Mexico, parts of Central America, and Africa’s Sahel Belt, all regions where rainfall will decline by as much as 50 percent. They’ll disperse from Calcutta and from the rest of the Ganges River Delta, where waters from melting Himalayan glaciers initially will intensify flooding and then disappear when the glaciers are gone, causing water shortages.

Because of climate change, human migrations could occur on an unprecedented scale in these areas by midcentury, according to a new report by researchers at the Columbia Center for International Earth Science Information Network, the United Nations University, and CARE International. The report, whose authors include Columbia geographers Alexander de Sherbinin, Susana Adamo, and Tricia Chai-Onn, is based on the first global survey of environmental and population projections. In Search of Shelter: Mapping the Effects of Climate Change on Human Migration and Displacement contains maps showing where and how large displacements could occur if temperatures continue to rise.

While the study doesn’t attempt to calculate how many people might be uprooted worldwide, estimates from other reports it cites range from 25 million to almost 700 million by 2050.

To mitigate the effects of climate change, de Sherbinin and his colleagues recommend that poor nations invest in low-till agriculture, irrigation technology that uses less water, disaster-preparedness systems, and economic diversification. The researchers say that nations also must begin planning to help resettle people from low-lying areas and to improve the ability of emigrants to send remittances to those left behind in affected regions.

 

 
 
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