THURSDAY, March 1 -- Scientists studying mice say they better understand how marijuana impairs working memory, the ability to momentarily retain and utilize information needed for comprehension and learning.

The study, published in the March 2 print issue of Cell, found that THC, the chief psychoactive ingredient in marijuana, impairs memory by affecting passive support cells known as astroglia, not active neurons as previously thought.

The memory changes are a major downside to the use of medical marijuana, the researchers said.

With these experiments in mice, "we have found that the starting point for this phenomenon -- the effect of marijuana on working memory -- is the astroglial cells," researcher Giovanni Marsicano, of INSERM in France, said in a journal news release. Evidence is mounting that these cells play a more active role than once believed in connecting neurons, not just nourishing them, he noted.

The study authors said these cells, also known as astrocytes, could have additional effects on other forms of memory. They said their findings shed light on how the brain works and could eventually help scientists find a way to deal with working memory problems stemming from other causes.

Research involving animals should be considered preliminary because the results often don't have implications for humans.

-- Mary Elizabeth Dallas

SOURCE: Cell, news release, March 1, 2012

THURSDAY, March 1 -- Children with autism often display challenging behaviors, but new research suggests that parents can learn to better handle tantrums and aggression, which may improve their child's overall functioning.

"Parent training is one of the best, evidence-supported treatment interventions in child psychiatry for other conditions, such as for children with ADHD or children with oppositional defiant disorder," said senior study author Lawrence Scahill, a professor at Yale University School of Nursing and Child Study Center in New Haven, Conn. "But strangely enough, it had never really been tried with children with autism or with developmental disabilities, so we had to make our own manual."

The study involved 124 children aged 4 to 13 with an autism spectrum disorder and serious behavioral issues, including daily, prolonged tantrums, aggression or self-injurious behavior. The children were prescribed risperidone (Risperdal), an antipsychotic drug approved by the U.S. Food and Drug Administration for treating severe behavioral problems in children with autism.

Half the children and their parents were also assigned to a six-month, structured "parent training" program. Parents were asked to identify the most difficult, disruptive behaviors and to think about what preceded the incidents and why the child might do it. They then worked with counselors to devise strategies to avoid the triggers and help the child respond better to the everyday stressors.

Parents who underwent training reported a greater decrease in problem behaviors than the parents of children on medication alone, researchers found. By the end of the study, the average dose of risperidonewas lower for kids in the parent-training group.

"On the tantrums, the aggression and the self-injury, the combination of medications and parent training was better," said Scahill. "How much better? Not a huge amount, but it was an incremental improvement over an already effective improvement."

Parents who received training also reported improvements on a test known as the Vineland Adaptive Behavior Scale, which measures how well a child does everyday activities, such as communicating, socializing, dressing, eating at the table and going to school.

By diminishing serious problem behaviors, such as tantrums and aggression, children's skills in other areas improved, but the difference was not statistically significant.

Autism is a neurodevelopmental disorder characterized by impaired social interaction, verbal and nonverbal communication, restricted interests and behaviors, repetitive behaviors and sometimes intellectual disability.

The study is published in the February issue of the Journal of the American Academy of Child & Adolescent Psychiatry.

Researchers plan to share the manual with the public. The training involves in-person sessions with a parent-training therapist, phone sessions and home visits that take place over several months.

Dr. Joseph Horrigan, assistant vice president and head of medical research for Autism Speaks, said studies like this provide more evidence that parent training can help kids and their families cope with autism-related behavioral problems.

The approach is "pragmatic and practical," he added. "We're all doing our best as parents, but we can all use a second set of eyes and an expert opinion to better our game, and this is shedding that light on the technique."

It also makes the point that medication isn't the only way to help kids with autism, he added.

In any case, not all children with autism should or would be prescribed risperidone, experts said. The drug, also used to treat schizophrenia and bipolar disorder, is for children with very serious behavioral issues that affect their ability to function in daily life in an extreme way, Scahill said.

Parents shouldn't take the term "parent training" to mean they are doing something wrong, Scahill said. Rather, with an expert's help they may learn tricks that make their life -- and their child's life -- a little easier.

"One of the first things I tell parents, we are not blaming the parents," he said. "Children with an autism spectrum disorder present unique challenges to parents. Children with autism spectrum disorder who also have disruptive behaviors present even more challenges."

"If a parent had a child with a serious medical condition like diabetes or asthma, there are all kinds of things that parent would have to learn that average parents don't, and so it is with children with autism spectrum disorder," he added. "There is no reason to think a parent would automatically know how to manage these problems."

SOURCES: Lawrence Scahill, professor, M.S.N, Ph.D., Yale University School of Nursing and the Child Study Center, New Haven, Conn; Joseph Horrigan, M.D., assistant vice president, head, medical research, Autism Speaks, New York City; February 2012, Journal of the American Academy of Child & Adolescent Psychiatry

WEDNESDAY, Feb. 29 -- Sports-related concussions are common in the United States, but there are many misconceptions about this type of head injury, according to an expert.

While it's widely believed that everyone with a concussion requires an immediate CT scan or MRI, concussion damage occurs at the microscopic level and cannot be seen on MRI or CT scans of the brain, said Dr. Howard Derman, director of the Methodist Concussion Center in Houston.

A physical exam is required to assess patients for concussion signs and symptoms of concussion, which can appear immediately after the head injury or days later. Signs and symptoms include: appearing dazed or stunned; answering questions slowly; nausea and vomiting; sensitivity to light or noise; and an inability to recall events prior to the hit to the head.

Many people wrongly believe that treating concussion-related headaches might mask some concussion symptoms. Derman said over-the-counter pain relievers are fine okay to use in conjunction with a doctor-approved return-to-activity regimen. In some cases, prescription pain relievers may be needed.

Another common myth is that a person with a concussion should not fall asleep even though they may be drowsy. In fact, drowsiness is a common concussion symptom and getting rest is sometimes the best thing to do, Derman said.

Getting plenty of sleep and allowing the brain to heal results in a faster recovery. Family members or other caregivers should check on the concussed person at least every few hours to make sure they can be easily awakened, he advised.

Children and teens do not recover from concussions at the same rate as adults, as was once believed. Because of their ongoing brain development, children and teens are more susceptible to serious head injury and post-concussion syndrome, a complex set of neurologic and psychological disorders that can last for weeks or even years after the injury and interfere with school, social activities and relationships.

Another misconception is that concussion causes no long-term effects. In fact, long-term effects can include depression and anxiety; blurred and double vision; mental impairment and increased risk of early-onset dementia.

March is National Brain Injury Month.

-- Robert Preidt

SOURCE: Methodist Hospital, Houston, news release, Feb. 16, 2012

WEDNESDAY, Feb. 29 -- A drug that's typically used to treat the flu and Parkinson's disease appears to speed recovery in traumatic brain injury patients, a new study indicates.

Traumatic brain injury (TBI) victims who weren't fully conscious and were discharged to rehabilitation facilities after hospitalization were given amantadine hydrochloride. The drug is already given "off-label" to such patients, but if and how much it helps has remained unclear.

While taking the drug, the patients given amantadine scored better on behavioral tests that measure how well the brain is functioning compared to a group of patients given a placebo, researchers report in the March 1 issue of The New England Journal of Medicine.

"Amantadine appeared to increase the rate of recovery compared to placebo. Patients got better faster while they were on the drug," said study co-author Joseph Giacino, director of rehabilitation neuropsychology at the Spaulding Rehabilitation Hospital, in Boston, and an associate professor in the department of physical medicine and rehabilitation at Harvard Medical School.

Study co-author Dr. John Whyte, director of the Moss Rehabilitation Research Institute at Albert Einstein Healthcare Network, in the Philadelphia area, said previous observational studies had suggested amantadine improved the rate of recovery. While the medicine is already commonly prescribed off-label to treat people suffering from prolonged disorders of consciousness, he said this is the first placebo-controlled trial of the drug in patients who were either in a vegetative state (wakeful but not aware) or a minimally conscious state (able to track with their eyes).

"There were many hypotheses out there about what this drug should do, but there was very little data to support or refute those hypotheses," Whyte explained.

For the study, 184 patients from 11 medical centers in three countries were enrolled. They had all suffered a TBI within the previous one to four months. Half received amantadine while the other half were given a placebo for the first four weeks of the six-week study. Both groups were followed up for two additional weeks, Whyte said.

The researchers used the Disability Rating Scale (DRS) to monitor patients' progress during the treatment and follow-up period. The test measures eye opening, verbal ability and motor response, among other functions, Giacino said.

"During the four-week treatment period, recovery was significantly faster in the amantadine group than the placebo group," said Giacino.

Whyte said during his 25-year career as a brain trauma rehabilitation physician there have been no groundbreaking treatments for these patients. TBI rehabilitation can take months, or years, and many patients do not have the health insurance or private funds to access good rehabilitative care, so a drug that could speed recovery would be a boon, he said.

The ability of patients in a vegetative state or those in the MCS "to access rehab has gotten less and less," Whyte said. "Many of these patients go straight to a nursing home or home with family." He noted that TBI remains the most common cause of death and disability in people between the ages of 15 and 30.

The new finding "is very exciting because we have a new tool to help improve these patients in their early outcome," said one expert, Dr. J. Javier Provencio, director of the Neurocritical Care Fellowship Program at the Cerebrovascular Center of the Cleveland Clinic Neurological Institute.

"The take-home message is that this medicine is promising for patients in a very certain setting. I think the results have to be taken very strictly and not extrapolated to other conditions," said Provencio.

He noted that the rate of improvement in the drug group slowed in weeks five and six. By the study's end, the overall improvement from baseline between the placebo group and the amantadine group was identical.

That means that, "it is still unclear whether the effects last," Provencio said. "In the study, by week six, the effect difference was getting smaller. I hope they follow these patients out to a year to see how they do."

Co-author Giacino said the researchers were surprised when they saw an immediate leveling off between the two groups in the final two weeks.

"But when I take a step back, it is even stronger evidence that this drug was doing something," he added.

Neurologist Dr. Daniel Labovitz, of Montefiore Medical Center in New York City, believes hope should remain in check despite the promising results. "It's not a home run. It's a small change and it was temporary, and I think that would be the message that has to come through."

Labovitz said the drug appears to be gently waking the patients. "If this trial holds up in larger, longer-term studies, maybe you can enhance the ability of [rehabilitation] therapists to interact with patients while they're on the drug."

Giacino said they researchers also aimed to look at side effects of amantadine.

"There was not a single category where the amantadine group had a higher rate of side effects than the placebo group," he said.

Whyte said that while this research may influence more rehabilitation experts to use amantadine for this type of patient, more challenges remain before the drug's impact is completely understood.

"This study isn't the end of the story," Whyte said.

SOURCES: Joseph Giacino, Ph.D., director, rehabilitation neuropsychology, Spaulding Rehabilitation Hospital, Boston, and associate professor, department of physical medicine and rehabilitation, Harvard Medical School; John Whyte, M.D., Ph.D., director, Moss Rehabilitation Research Institute, Albert Einstein Healthcare Network, and Brain Injury Program, Bryn Mawr Rehab Hospital, Philadelphia; J. Javier Provencio, MD, director, Neurocritical Care Fellowship Program, Cerebrovascular Center, Cleveland Clinic Neurological Institute; Daniel Labovitz, MD, neurologist, Montefiore Medical Center, New York City; March 1, 2012, New England Journal of Medicine