Young people who occasionally smoke marijuana may be rewiring their brains, with their pot use causing structural changes to brain regions related to motivation, emotion and reward, a small study says.
Recreational pot use by a small group of young adults caused significant changes to the shape and density of both the nucleus accumbens, a region of the brain involved in reward and addiction, and the amygdala, which helps process emotion and form long-term memories, the study authors reported.
These changes show that pot users' brains adapt to even low-level marijuana exposure, potentially making a person more vulnerable to drug addiction or changing their thought processes and emotions in unknown ways, the researchers said.
"These are two brain regions you do not want to mess around with," said study senior author Dr. Hans Breiter, a professor of psychiatry and behavioral science at Northwestern University Feinberg School of Medicine. "All parts of the brain are important, but some, like these, are more fundamental. It raises a very serious issue, given that we saw these changes in casual marijuana users."
Previous research had revealed similar changes in brain structure among heavy marijuana users. But this is the first study to show that even casual use of the drug can alter a person's brain, said study lead author Jodi Gilman, a researcher with the Massachusetts General Hospital Center for Addiction Medicine.
"We were interested in looking at these young adults who aren't addicted," Gilman said. "They aren't reporting any problems from marijuana, and yet we still see these brain changes."
These findings could take on significance as more and more states consider legalizing marijuana, following the example already set by voters in Colorado and Washington.
Read more from U.S. News.
An outbreak of Ebola in West Africa has been linked to the deaths of more than 120 people, according to the latest World Health Organization count.
There is no vaccine and no cure for the deadly virus, and its appearance in West Africa, far from its usual sites in Central and East Africa, has caused some panic.
Health workers are trying to contain its spread, tracking down anyone with whom the sick have had contact. Mali announced Tuesday that samples from all its suspected cases had tested negative for the disease.
Malian Health Minister Ousmane Kone said that the country had sent out 10 samples for testing at labs in the United States and Senegal, and all were declared negative for Ebola. There are no other known suspected cases in the country.
The U.N. health agency said it had recorded a total of 200 suspected or confirmed cases of Ebola, the majority of which are in Guinea. That figure includes some of the Mali cases that the government now says are negative. The organization said the deaths of 121 people in Guinea and Liberia have been linked to the disease.
Officials have said the current outbreak could last months.
A patient in a Minnesota hospital is confirmed to be carrying Lassa fever, an acute viral disease common in West Africa but rare in the U.S. The man who had traveled from West Africa was hospitalized with fever and confusion. The U.S. Centers for Disease Control and Prevention's study of blood samples confirmed Lassa fever, which is similar to Ebola. The last case of the disease in the United States was in 2010.
Rodents in West Africa carry the Lassa virus and transmit it to humans through contact with urine or droppings. Though rare, it can also be transmitted from person to person through blood or bodily fluids. The virus is not transmitted through casual contact.
The Minnesota Department of Health says the general public is not at risk. But it and the CDC are working with the hospital to notify any health care providers and airline passengers and crew who may have had contact with the patient.
About 100,000 to 300,000 cases of Lassa fever and about 5,000 deaths occur annually in West Africa. Eighty percent of human infections don’t show any symptoms. The Minnesota patient is recovering.
Read more about Lassa fever at www.cdc.gov/vhf/lassa/.
New research on mammography suggests the benefits of this routine test don't actually outweigh the risks for many women.
That means a woman's decision to have mammography should be individualized, researchers said.
Report co-author Dr. Nancy Keating, an associate professor of Health Care Policy at Harvard Medical School, said their analysis indicates mammography guidelines should be based on each individual patient's complete health profile, such as family and medical history, genetic risk factors and overall life expectancy. Researchers studied 50 years of breast cancer research.
"Mammography does have some benefit in the likelihood of dying from breast cancer, but these benefits are relatively modest," Keating told CBS News. "Particularly for women who are at very low risk of breast cancer -- the benefits are quite small."
The authors found mammography reduces breast cancer mortality rates overall by about 19 percent. For women in their 40s, regular screening with mammography only lowered breast cancer-related deaths by around 15 percent. Post-menopausal women were found to benefit the most from annual mammography; the screening test lowered death rates of women in their 60s by 32 percent.
Overall U.S. women have a 12.3 percent lifetime risk for developing the breast cancer. About 40,000 women will die from the disease this year, according to the American Cancer Society.
Mammography is the most common screening test for breast cancer but it's not always accurate. Statistically, mammography misses about 20 percent of breast cancer malignancies, according to the National Cancer Institute. On the other hand, the test can also lead to false positive results, over-diagnosis and even unnecessary treatment.
By the authors' calculations, more than half of the women who have routine mammography over 10 years can expect a false positive diagnosis, and 20 percent of these false positives will lead to unnecessary biopsies.
Another controversial study, published in February by the British Medical Journal, tracked 90,000 women who had routine mammograms over a period of 25 years. That study also found regular mammograms didn't necessarily lower risk for breast cancer death, even for women in their 50s, when the risk for developing the disease typically starts to increase.
Read more from CBS News.
As many as one in 68 U.S. children may have autism, U.S. health officials said on Thursday, a sharp increase over an estimate of 1 in 88 children just two years ago that raises questions about why the number has risen so dramatically.
Researchers at the U.S. Centers for Disease Control and Prevention noted in their report that the data, gleaned from a study of children in 11 communities, could not be generalized to the national population.
They also did not study why the rates were so much higher, but there are some clues. In the latest report, almost half of children identified as having autism also had average or above-average IQ levels, compared with just a third of children a decade ago.
"It could be doctors are getting better at identifying these children; it could be there is a growing number of children with autism at higher intellectual ability, or it may be a combination of better recognition and increased prevalence," Coleen Boyle, director of the CDC's National Center on Birth Defects and Developmental Disabilities, said in a conference call.
Some experts believe the higher rates reflect a heightened focus on autism by parents, doctors and teachers that may be resulting in more children being diagnosed with the disorder.
In its latest report, the CDC studied medical, school and other records of 8-year-olds within 11 U.S. communities to determine whether a child had autism.
There were significantly different rates by region, ranging from 1 in 175 children in Alabama to 1 in 45 children in New Jersey, which could reflect access to healthcare and other factors.
The current study looked at fewer sites than the data reported in 2012, which included 14 communities, but the CDC said it did not change the criteria used to diagnose autism.
In this latest report, which looks at data from 2010, the researchers found 14.7 per 1,000 eight-year-olds had autism, compared with the previous estimate of 11.3 per 1,000 eight year olds in its 2012 estimate, which used data from 2008.
The CDC said the latest data continue to show that autism is almost five times more common among boys than girls, affecting 1 in 42 boys versus 1 in 189 girls.
White children are more likely to be identified as having autism spectrum disorder than are black or Hispanic children
--Julie Steenhuysen, Reuters