The Teen Brain on Weed

April 25, 2015 by

April 24, 2015

By Medical Discovery News

A brain

It is now legal to use marijuana (recreationally and/or medically) in more than 20 states and the District of Columbia, and as more places debate legalizing the substance, more people are asking about its consequences on human health. There are many myths and misconceptions out there, but this is what science has to say about the subject.

As with all substances, the health effects depend on the potency, amount, and a person’s age. An independent scientific committee in the United Kingdom evaluated how harmful various drugs were based on 16 criteria and ranked heroin, crack cocaine, and methamphetamine as the most harmful drugs to individuals using them, and ranked alcohol, heroin, and crack cocaine as the drugs that cause the most harm to others. Marijuana ranks eighth, with slightly more than one-quarter the harm of alcohol.

Short-term use is associated with impaired short-term memory, making it difficult to learn and retain information while under the influence. Short-term use can also impair motor coordination, interfering with tasks such as driving. The overall risk of an accident doubles if a person drives soon after using marijuana. In comparison, those with blood alcohol levels above the legal limit are five times more likely to have an accident, and the combination of alcohol and marijuana is higher than either one alone.

Long-term or heavy use is associated with diminished life satisfaction and achievement overall. At high doses, marijuana can cause paranoia and psychosis, and long-term marijuana use increases the risk of developing schizophrenia or other chronic psychotic illnesses. Nine percent of all marijuana users, or 2.7 million people, develop an addiction to it. That figure jumps to 25-50 percent for those who use marijuana daily, and 17 percent of people who begin using marijuana as adolescents become addicted. Cannabis withdrawal syndrome is real and includes symptoms of irritability, sleep disturbance, dysphoria, craving, and anxiety.

Adults who occasionally use marijuana do so with little to no risk, but adolescent brains are not fully developed, making them more vulnerable to the adverse effects of marijuana. Using marijuana during adolescence can alter brain development, causing impaired cognition and lower IQs. This is probably because the active ingredient in marijuana, tetrahydrocannabinol, affects the brain’s ability to make connections between neurons in certain regions of the brain. Adolescent marijuana users also have a smaller hippocampus, which is important in learning and memory, and a less active prefrontal cortex, which is important in cognitive tasks such as planning and problem-solving.

Since acute marijuana intoxication can impair cognitive functions for days, students who use marijuana may function well below their natural abilities, causing academic difficulties. High school dropouts do report higher marijuana usage than their peers. Some evidence suggests that these cognitive impairments could be long-lasting or permanent in long-term users who started at younger ages, which can impact their abilities to succeed academically and professionally.

There is no clear association between long-term marijuana use and any deadly disease, although chronic marijuana smokers have increased rates of respiratory infections and pneumonia and an increased risk of heart attack and stroke. The effects of marijuana on a developing embryo and the effects of second-hand or third-hand marijuana smoke have not been well-studied, but as marijuana legalization continues to be an issue the science behind it will as well.

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Does Grey Matter?

August 9, 2014 by

Aug. 8, 2014

By Medical Discovery News

The brain

What do brain scientists and fans of E. L. James have in common? They are both passionate about shades of grey. Results from a recent study in the scientific journal “Molecular Psychiatry” indicate that grey matter really does, well, matter. This study shows that the thickness of grey matter in the brain may be linked to intelligence and may also explain why some people have learning difficulties.

Grey matter is the outermost region of the brain, a layer of tissue two to four millimeters thick covering the brain on both sides with a wrinkled surface. Underneath the grey matter, also called the cerebral cortex, is the white matter of the brain, the cerebrum.

Grey matter is responsible for some major human functions including awareness, attention, consciousness, language, thought, and memory. Previous studies have shown that animals with bigger brains generally have thicker cortexes, but there has not been a strict link between intelligence and the thickness of the grey matter until now. 

For this new study, researchers at King’s College London’s Institute of Psychiatry obtained brain scans and DNA samples from 1,583 14-year-olds. They also tested the verbal and nonverbal intelligence of these subjects. Using DNA analysis, scientists looked for gene variants that could be responsible for the intelligence differences of this group. This proved to be a daunting task as they discovered more than 50,000 gene variants associated with brain development. However, with the help of computation biology, researchers uncovered some astounding results. Those with one particular gene variant caused by a single nucleotide polymorphism (or change) had thinner grey matter on the left side of their brains. And, these same individuals tested lower on the intelligence tests. 

Called NPTN, this gene encodes a protein that works in brain cells called neurons. The variant of NPTN affects communication between neurons in the brain, thereby explaining its impact on important functions of grey matter. Additional experiments suggest the NPTN variant may have more of an effect in the left side of the brain than the right side. This may correlate to lower intelligence due to the function of this important gene and its encoded protein in the left brain. 

While important, NPTN is not the only thing that determines intelligence – a multitude of other genes and environmental influences are clearly involved as well. However, this gene may provide new clues as to how intelligence is built in humans. Also, it will be interesting to see if this gene variant is associated with cognitive diseases like autism or psychological disorders like schizophrenia. 

Thanks to the new B.R.A.I.N. initiative that funds basic and translational research, we look forward to better understanding the human brain, arguably one of the most important human organs we know the least about. 

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A Blood Test for Suicide

May 2, 2014 by

May 2, 2014

By Medical Discovery News

The 10th leading cause of death in America is completely preventable – suicide.  In 2010, 38,364 people died by suicide, more than chronic liver disease, septicemia, and Parkinson’s disease.

While strongly linked to depression, there are not always clear warning signs that someone is about to commit suicide. Unlike a viral or bacterial infection where there can be a number of signs like changes in body temperature, white blood cells, and signaling molecules, there is no simple clinical test to diagnose suicidal tendencies. Now, new research is working toward a blood test using biomarkers that may identify those likely to commit suicide. 

Biomarkers are biological materials that are seen under specific conditions. For example, during a viral infection proteins called cytokines are produced by the human body to help defend cells and tissues from the virus. Identifying these proteins is a signature of viral infection. The challenge is that these signatures change over the course of the infection and different viruses can produce different signatures. Scientists have been working extensively to use this concept of biomarkers to help with the early detection of other diseases from cancer to Alzheimer’s. 

Researchers at the University of Indiana want to design a simple blood test to detect a specific biomarker to identify those who might be at risk for suicide. They have been looking for protein biomarkers that can distinguish different psychological states. For example, can specific biomarkers tell if someone with bipolar disorder is in a high or low mood? In this recent study, researchers looked for biomarkers in individuals contemplating suicide. Every three to six months, they interviewed and drew blood from their subjects – 75 men with bipolar disorder – and rated their risk of suicide from low to high. Several proteins in the blood varied with these mood swings but one in particular caught researchers’ attention. The protein SAT1 was present in all of those with high indications of suicidal thoughts. SAT1 plays a role in the body’s response to stressful situations.

They then tested suicide victims, grouping them by age and gender, and found high levels of SAT1 in all of them. Finally, they took blood samples regularly from about 80 men with either schizophrenia or bipolar disorder. The study showed higher SAT1 levels in those who were later hospitalized for suicidal behavior. The presence of elevated SAT1 was more than 80 percent predictive of hospitalization. Overall, these are promising results.

SAT1 is not an absolute signature for suicide because many things that can affect its levels. And like any complex behavior, there are a multitude of factors involved. Other biomarkers will need to be identified to create a biosignature for suicide. But this is an exciting discovery that may be used to prevent the tragic deaths of many people in the future.   

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