Brain

Here are just a few of the health effects you may want to know:

• Marijuana use directly affects the brain—specifically the parts of the brain responsible for memory, learning, and attention.
• The compounds in marijuana can affect the circulatory system and may increase the risk of heart attacks and strokes.
• Smoking marijuana can lead to a greater risk of bronchitis, cough, and phlegm production.
• Marijuana users are significantly more likely than nonusers to develop chronic mental disorders, including schizophrenia. Schizophrenia is a type of mental illness where people might see or hear things that aren't really there (hallucinations).
• Eating foods or drinking beverages that contain marijuana have some different risks than smoking marijuana, including a greater risk of poisoning.
• About 1 in 10 marijuana users will become addicted. For people who begin using before the age of 18, that number rises to 1 in 6.
• Some research shows that using marijuana while you are pregnant[288 KB] can cause health problems in newborns—including low birth weight and developmental problems.
• Marijuana use can slow your reaction time and ability to make decisions when driving[271 KB].

“We see specific morphological changes in the brain to important neurotransmitter systems, and individuals who are exposed to THC early in life show greater sensitivity to opiates than others do,” she said. “We know that the brain definitely adapts to marijuana. It is profoundly changing the receptors and receptor signaling that impact gene expression. And the changes it makes last through adulthood and even into the next generation. So we see that there’s something about the ongoing processes in the developing brain that this drug somehow sensitizes—in the cells, the receptors, and in the signaling cascades—that makes kids more vulnerable to addiction and other problems later.”

“There is a lot of optimism for what components of the marijuana plant may offer on a medicinal level but, like all other drugs, the caveat is that you have to know what it does, what population it can be used for, and who could be vulnerable to its effects. We need a lot more research before we can say anything concrete about its future as a treatment.”

Summary: Cannabis use during pregnancy is associated with abnormal brain structure in children, according to a new study. Compared with unexposed children, those who were prenatally exposed to cannabis had a thicker prefrontal cortex, a region of the brain involved in complex cognition, decision-making, and working memory.

Thus, adolescent THC exposure induced behavioral abnormalities resembling positive and negative schizophrenia-related endophenotypes and a state of neuronal hyperactivity in the mesocorticolimbic dopamine (DA) pathway. Furthermore, we observed profound alterations in several prefrontal cortical molecular pathways consistent with sub-cortical DAergic dysregulation. Our findings demonstrate a profound dissociation in relative risk profiles for adolescent versus adulthood exposure to THC in terms of neuronal, behavioral, and molecular markers resembling neuropsychiatric pathology.  

Brain abnormalities and memory problems were observed in these individuals in their early twenties, two years after they had stopped using marijuana. The cannabis users were noted to have striatal, globus pallidus, and thalamus changes showing these brain regions appearing to shrink and collapse inward. These individuals also had poorer working memory. The earlier the age of cannabis use, the more dramatic the brain changes and memory deficits were noted to be.
Not only does it appear that cannabis use itself is a potential precursor to future drug use, but the age of first use of cannabis and the frequency of cannabis use seem to also be predictors of future substance abuse issues. Studies have shown that over two-thirds of those under the age of 18 who have been admitted to a drug treatment program identify cannabis as their substance of choice.
” One important characteristic that defines a substance use disorder is “an underlying change in brain circuits that may persist beyond detoxification, particularly in individuals with severe disorder"

The damaging effects remain even if the person stops smoking the drug
·         Teenagers are at particular risk because their brains are still developing
·         Smoking cannabis affects critical thinking and memory
·         Researchers warn that stronger varieties today are causing more damage 

For the first time, researchers at Northwestern University have analyzed the relationship between casual use of marijuana and brain changes – and found that young adults who used cannabis just once or twice a week showed significant abnormalities in two important brain structures.

 cannabis use during pregnancy can increase the risk for ill‐behaviors (Goldschmidt et al, 2004; Day et al, 2011
Data suggest that administration of THC during pregnancy can induce long‐term structural and functional modifications of the cortical circuitry.
Maternal cannabis use during pregnancy reduces SCG10 in human fetal cerebrum

In radioactive tracing studies, scientists found that tetrahydrocannabinol (THC), the active ingredient in marijuana, binds to specific receptors called cannabinoid receptors, many of which coordinate movement. This may explain why people who drive after they smoke marijuana are impaired. The hippocampus, a structure involved with memory storage and learning, also contains many receptors for THC. This finding provides some insight into why heavy users or those intoxicated on marijuana have poor short-term memory and problems processing complex information.