Detailed Instructions: In this task, you are given a text of many news articles seperated by special token "|||||". Your task is to summarize them.
Q: Study shows marijuana’s long-term effects on the brain 
  
 The effects of chronic marijuana use on the brain may depend on age of first use and duration of use, according to researchers at the Center for BrainHealth at The University of Texas at Dallas. 
  
 In a paper published today in Proceedings of the National Academy of Sciences (PNAS), researchers for the first time comprehensively describe existing abnormalities in brain function and structure of long-term marijuana users with multiple magnetic resonance imaging (MRI) techniques. Findings show chronic marijuana users have smaller brain volume in the orbitofrontal cortex (OFC), a part of the brain commonly associated with addiction, but also increased brain connectivity. 
  
 “We have seen a steady increase in the incidence of marijuana use since 2007,“said Dr. Francesca Filbey, Associate Professor in the School of Behavioral and Brain Sciences at the University of Texas at Dallas and Director of the Cognitive Neuroscience Research in Addictive Disorders at the Center for BrainHealth. “However, research on its long-term effects remains scarce despite the changes in legislation surrounding marijuana and the continuing conversation surrounding this relevant public health topic.” 
  
 The research team studied 48 adult marijuana users and 62 gender- and age-matched non-users, accounting for potential biases such as gender, age and ethnicity. The authors also controlled for tobacco and alcohol use. On average, the marijuana users who participated in the study consumed the drug three times per day. Cognitive tests show that chronic marijuana users had lower IQ compared to age-and gender-matched controls but the differences do not seem to be related to the brain abnormalities as no direct correlation can be drawn between IQ deficits and OFC volume decrease. 
  
 “What’s unique about this work is that it combines three different MRI techniques to evaluate different brain characteristics,” said Dr. Sina Aslan, founder and president of Advance MRI, LLC and adjunct assistant professor at The University of Texas at Dallas. “The results suggest increases in connectivity, both structural and functional that may be compensating for gray matter losses. Eventually, however, the structural connectivity or ‘wiring’ of the brain starts degrading with prolonged marijuana use.” 
  
 Tests reveal that earlier onset of regular marijuana use induces greater structural and functional connectivity. Greatest increases in connectivity appear as an individual begins using marijuana. Findings show severity of use is directly correlated to greater connectivity. 
  
 Although increased structural wiring declines after six to eight years of continued chronic use, marijuana users continue to display more intense connectivity than healthy non-users, which may explain why chronic, long-term users “seem to be doing just fine” despite smaller OFC brain volumes, Filbey explained. 
  
 “To date, existing studies on the long-term effects of marijuana on brain structures have been largely inconclusive due to limitations in methodologies,” said Dr. Filbey. “While our study does not conclusively address whether any or all of the brain changes are a direct consequence of marijuana use, these effects do suggest that these changes are related to age of onset and duration of use.” 
  
 The study offers a preliminary indication that gray matter in the OFC may be more vulnerable than white matter to the effects of delta-9-tetrahydrocannabinol (THC), the main psychoactive ingredient in the cannabis plant. According to the authors, the study provides evidence that chronic marijuana use initiates a complex process that allows neurons to adapt and compensate for smaller gray matter volume, but further studies are needed to determine whether these changes revert back to normal with discontinued marijuana use, whether similar effects are present in occasional marijuana users versus chronic users and whether these effects are indeed a direct result of marijuana use or a predisposing factor. 
  
 The research was funded by the National Institute on Drug Abuse to Dr. Filbey (R01 DA030344, K01 DA021632). ||||| The existing literature on the long-term effects of marijuana on the brain provides an inconsistent picture (i.e., presence or absence of structural changes) due to methodological differences across studies. We overcame these methodological issues by collecting multimodal measures in a large group of chronic marijuana using adults with a wide age range that allows for characterization of changes across lifespan without developmental or maturational biases as in other studies. Our findings suggest that chronic marijuana use is associated with complex neuroadaptive processes and that onset and duration of use have unique effects on these processes. 
  
 Abstract 
  
 Questions surrounding the effects of chronic marijuana use on brain structure continue to increase. To date, however, findings remain inconclusive. In this comprehensive study that aimed to characterize brain alterations associated with chronic marijuana use, we measured gray matter (GM) volume via structural MRI across the whole brain by using voxel-based morphology, synchrony among abnormal GM regions during resting state via functional connectivity MRI, and white matter integrity (i.e., structural connectivity) between the abnormal GM regions via diffusion tensor imaging in 48 marijuana users and 62 age- and sex-matched nonusing controls. The results showed that compared with controls, marijuana users had significantly less bilateral orbitofrontal gyri volume, higher functional connectivity in the orbitofrontal cortex (OFC) network, and higher structural connectivity in tracts that innervate the OFC (forceps minor) as measured by fractional anisotropy (FA). Increased OFC functional connectivity in marijuana users was associated with earlier age of onset. Lastly, a quadratic trend was observed suggesting that the FA of the forceps minor tract initially increased following regular marijuana use but decreased with protracted regular use. This pattern may indicate differential effects of initial and chronic marijuana use that may reflect complex neuroadaptive processes in response to marijuana use. Despite the observed age of onset effects, longitudinal studies are needed to determine causality of these effects. ||||| Experimental mice have been telling us this for years, but pot-smoking humans didn't want to believe it could happen to them: Compared with a person who never smoked marijuana, someone who uses marijuana regularly has, on average, less gray matter in his orbital frontal cortex, a region that is a key node in the brain's reward, motivation, decision-making and addictive behaviors network. 
  
 More ambiguously, in regular pot smokers, that region is better connected than it is in non-users: the flow of signal traffic is speedier to other parts of that motivation and decision-making network, including across the superhighway of "white matter" that connects the brain's hemispheres. 
  
 The researchers who conducted the study speculate that the orbital frontal cortex's greater level of "connectedness"--which is especially pronounced in people who started smoking pot early in life--may be the brain's way of compensating for the region's under-performing gray matter. Whether these "complex neuroadaptive processes" reverse themselves when marijuana use stops is an important unanswered question, they added. 
  
 The new findings, reported Monday in the journal PNAS, confirm findings about chronic marijuana use from rodents. But scientific evidence in humans has been more mixed. 
  
 Even now, however, the authors of the study acknowledge that they cannot discern whether a pot smoker's smaller orbital frontal cortex is the cause or the result of chronic marijuana use. A 2012 study found that subjects with a smaller orbital frontal cortex at age 12 were more likely to start using marijuana by age 16, suggesting that deficits in this crucial region may predispose one to substance-abuse behaviors. 
  
 This study, conducted by researchers from the University of Texas' Center for Brain Health and the Albuquerque-based Mind Research Network, did not follow subjects over time, so it is at a disadvantage in showing cause and effect. Instead, it compared 48 "chronic" marijuana users (at least four times a week over the past six months) with 62 non-using control subjects who were matched for age and gender with the using group. Subjects were an average age of 28 to 30 years old. 
  
 Researchers noted that the IQ of the marijuana-using group was significantly lower than that of the non-using group--not a finding of the study, but an incidental factor that might be indirectly linked to marijuana use. 
  
 Follow me on Twitter @LATMelissaHealy and "like" Los Angeles Times Science & Health on Facebook. |||||  
  
 An unidentified man smokes medical marijuana during karaoke night at the Cannabis Cafe in Portland, Ore. (Rick Bowmer/Associated Press) 
  
 If you're confused about what marijuana use really does to people who use it, you're not alone. For years, the scientific research on health effects of the drug have been all over the map. 
  
 Earlier this year, one study suggested that even casual marijuana use could cause changes to the brain. Another found that marijuana use was also associated with poor sperm quality, which could lead to infertility in men. 
  
 But marijuana advocates point to other research indicating that the drug is far less addictive than other drugs, and some studies have found no relationship between IQ and marijuana use in teens. 
  
 Researchers at the Center for Brain Health at the University of Texas in Dallas sought to clear up some of the confusion with a study that looked at a relatively large group of marijuana users and evaluated their brains for a slew of different indicators. 
  
 What they found was complex, but the pattern was clear: The brains of marijuana users were different than those of non-marijuana users. The area of the brain responsible for establishing the reward system that helps us survive and also keeps us motivated was smaller in users than in non-marijuana users. But there was also evidence that the brain compensated for this loss of volume by increasing connectivity and the structural integrity of the brain tissue. 
  
 Those effects were more pronounced for marijuana users who started young. 
  
 "The orbitofrontal cortex is one of the primary regions in a network of brain areas called the reward system," explained Francesca Filbey, lead author of the study and an associate professor of the neurogenetics of addictive behavior at the University of Texas in Dallas. "It helps us determine what is good for us and what keeps us sustained. "In this case, the orbitofrontal cortex plays a role in drug use because drug use and things associated with it --paraphernalia for example -- are associated with the rewarding effects of drugs." 
  
 The study, published Monday in the Proceedings of the National Academy of Sciences, used MRI scans to look at the brains of 62 non-marijuana users and 48 regular marijuana users, 27 of whom used marijuana but not other drugs. The marijuana users reported ingesting the drug about three times a day -- very heavy use -- and had used it for an average of about 10 years. 
  
 Looking first at atypically heavy marijuana use is necessary to identify structural effects, if there are any, Filbey said. Subsequent research would look at varying levels of use to find out if differences compared to non-users are still observed. For example, in Colorado, only about 22 percent of marijuana users reported using the drug about once a day at most. 
  
 Relative to other studies, this one had a fairly large sample size; it also excluded participants who had symptoms of psychosis, brain injury or neurological disorders in order to reduce the likelihood that the tests would pick up on other confounding factors. And it looked at three brain characteristics: the volume of the orbitofrontal cortex, how connected that part of the brain was to other areas, and the structural integrity of the white matter. 
  
 "We found that while the orbitofrontal cortex was smaller, there was greater functional and structural connectivity," said Filbey. "The white matter seemed to have greater integrity than the [non-marijuana using group]. And the connection between the orbitofrontal cortex and other areas were stronger." 
  
 That's potentially positive news suggesting that whatever impact marijuana use might have on the size or volume of that part of the brain, it may be offset by better connectivity and structural soundness. "It suggests that there is definitely a more complicated pattern that the brain seems to be able to compensate for any kind of loss in order to keep that network maintained," Filbey said. 
  
 However, Filbey's research also indicated that some of these findings could be affected by how young the person was a the time that they started using marijuana and how long marijuana use continued. People who started younger appeared to show more protective effects -- stronger connectivity and integrity in their white matter. But the longer the person used the drug, those features began to erode. After about six or seven years of use, connectivity and integrity begin to erode. 
  
 "So whatever compensatory effects that there may be originally seemed to diminish with prolonged use," she added. 
  
 There is no proven connection between the structural characteristics of this area in the brain and certain behaviors in humans. And it is possible that the small orbitofrontal cortex observed in marijuana users predated their marijuana use. A 2012 study found that smaller orbital frontal cortex volume at 12 years of age appeared to predict the initiation of marijuana use later in life. 
  
 Further long-term research is needed to determine what if any effects cessation has on brain structures of marijuana users. 
  
 [This post has been udpated.] |||||
A:
A new study out of the University of Texas' Center for BrainHealth and the Mind Research Network is showing brain differences in regular pot users—differences that have already been reported in lab mice. The study, published in PNAS, found that 48 "chronic" users who smoked at least four times a week had less gray matter in the orbitofrontal cortex than 62 control subjects who didn't use pot, reports the Los Angeles Times. The orbitofrontal cortex "helps us determine what is good for us and what keeps us sustained," the lead author tells the Washington Post. It's unclear whether these "shrunken brains" are the result of chronic use or contribute to the tendency to use in the first place. Researchers also found that the orbitofrontal cortex is better connected in chronic users, with a faster signal flow throughout the motivation- and decision-making network and even across the white matter connecting the brain's left and right hemispheres. One possible explanation? That increased "connectedness" might be compensating for the not-up-to-snuff gray matter. That finding was more pronounced for users who started smoking pot young, "which may explain why chronic, long-term users 'seem to be doing just fine' despite smaller OFC brain volumes," according to a release. An earlier study from 2012 found that 12-year-olds with smaller orbitofrontal cortices were more likely to start using pot by age 16, indicating a possible predisposition to marijuana use in those with deficits in this part of the brain. (Marijuana use has also been linked to heart problems.)