Marijuana Users Have Abnormal Brain Structure and Poor Memory

Marijuana abuse and or use appears to foster brain changes that resemble various types of dementia, and including schizophrenia.

According to news reports teens who are or were heavy marijuana users -- smoking it daily for about three years -- have abnormal changes in their brain structures related to working memory and performed poorly on memory tasks,

A poor working memory predicts poor academic performance and everyday functioning.

Brain abnormalities and memory problems were observed during the individuals’ early twenties, two years or more after they stopped smoking marijuana, which could indicate the long-term effects of chronic use. As is true with all types of dementia, memory-related structures in the brain appear to shrink and collapse inward, possibly reflecting a decrease in neurons.

 The studies also show the marijuana-related brain abnormalities correlated with a poor working memory performance and look similar to schizophrenia-related brain abnormalities. Over the past decade, scientists, , have shown that changes in brain structure may lead to changes in the way the brain functions.

These are the first studies to target key brain regions in the deep subcortical grey matter of chronic marijuana users with structural Magnetic Resonance Imaging and to correlate abnormalities in these regions with an impaired working memory. Working memory is the ability to remember and process information in the moment and -- if needed -- transfer it to long-term memory. Previous studies have evaluated the effects of marijuana on the cortex, and few have directly compared chronic marijuana use in otherwise healthy individuals and individuals with dementia or schizophrenia.

The younger the individuals were when they started chronically using marijuana, the more abnormally their brain regions were shaped, the studies report. Findings suggest that these regions related to memory may be more susceptible to the effects of the drug if abuse starts at an earlier age.

Now, after marijuana has been decriminalised scientists suggest “ We Need More Research To Understand Its Effect On The Brain.”

In Canada and the United States ot the Americas, marijuana is the most commonly used recreational drug and young adults have the highest -- and growing -- prevalence of use. Decriminalization of the drug will, undoubtedly, lead to even greater use.

The groups in the studies mostly started using marijuana daily between sixteen(16) to seventeen 17 years of age and had been using it for about three years.

However, at the time of the studies, they had been marijuana free for about two years. In one of the studies ninety-seven (97) subjects participated, including matched groups of healthy controls, subjects with a marijuana use disorder, schizophrenia subjects with no history of substance use disorders, and schizophrenia subjects with a marijuana use disorder. The subjects who used marijuana did not abuse any other drugs.

Overall, few studies have examined marijuana’s effect on the deep regions in the brain -- the ‘subcortical grey matter’ below the noodle-shaped cortex. These studies are unique in that they look at the shapes of the striatum, Globus pallidus and thalamus, structures in the sub cortex that are critical for motivation and memory.

The abuse of popular street drugs, such as marijuana, may have dangerous implications for young people who are developing or have developed mental disorders

Chronic marijuana use could augment the underlying disease process associated with dementias and schizophrenia. While chronic marijuana smokers and chronic marijuana smokers with mild dementia and or schizophrenia both had brain changes related to the drug, subjects with the mental disorders had greater deterioration in the thalamus. That structure is the communication hub of the brain and is critical for learning, memory and communications between brain regions. The brain regions examined in this study also affect motivation, which is already notably impaired in people with dementia/schizophrenia.