Pot May Not Harm Your Kidneys, but It Will Make You Stupid

proves the medical effectiveness of cannabis, there are still some issues surrounding the use of the plant. For one thing, there are few long term established studies completed on cannabis due to its illegality. And aside from this some of the studies that have been completed are actually contradictory. The most hotly disputed aspect of weed is whether or not it will make long or short terms users slower.

Pot, Memory and Kidneys

A recent study has found that marijuana may not actually be bad for the kidneys as was commonly believed for a long time, but it might have an effect on memory. The study found that for habitual young users with existing psychotic disorders, weed will affect memory. It is important to note that there are a number of qualifiers in this statement. For young users who use daily and with a certain preexisting condition, it has been associated with a reduced IQ levels. To put this in context, young regular users with existing disorders are less than .1% of the population. But it could still be indicative of harmful effects of regular marijuana consumption for the wider population.

The study was published in the Clinical Journal of the American Society of Nephrology. While animal studies had previously shown that marijuana consumption resulted in weakened kidneys, this study showed no evidence that such was the case in young adults followed for up to 15 years. While there may be no need to worry about kidney failure just yet, studies have found that there are other reasons to be aware of frequent marijuana usage, especially in young adults whose bodies and brains are still growing. The study was a 20 years reviews conducted by Kings College Professor Wayne Hall and found some alarming statistics:

  • 17% of teenagers who smoke marijuana become dependent/lifelong users
  • Cannabis users do worse at school
  • Smoking marijuana while pregnant reduces the baby’s birth weight
  • 10% of adults who smoke go on to become regular users. They are more likely to go on to use harder drugs.
  • Cannabis use double the risk of psychotic disorders.

As damning as it sounds, the evidence on cannabis is mixed and most certainly not conclusive. Some studies indicate that cannabis use only impairs memory when the user is under the influence, and that when cannabis use stops the memory comes back. It does stand to reason that young adults who smoke once would tend to keep on using mainly for the social associations. There is no chemical dependency on marijuana, but a psychological one that breeds laziness and lack of motivation in young adults who do not have strong psychological development to resist these tendencies.

This is not the only study showing that early cannabis use can have detrimental effects on intelligence. A 2007 New Zealand study tested 70 adolescents, and found that those who reported they were regular cannabis users were more likely to get lower test scores than those who never smoked or smoked infrequently. They scored worse on attention, spatial memory and learning. There is also evidence to suggest that adolescents who smoke cannabis may take longer to return to baseline compared to adults, as they retain cannabis compounds for longer.

Cannabis and Intelligence

In some preclinical trials, cannabis compounds have actually encouraged the growth of new brain cells, and cannabis compounds can actually encourage the growth of neurogenesis, meaning that new neurons actually grow. It is generally accepted that cannabis is good for creativity as it encourages the formation of new neural networks, which might explain why some strains are so favored by artists, musicians and writers.

There are two main forms of memory, short term memory and long-term memory. Studies have shown thatshort-term memory is definitely impaired when under the influence of cannabis. Users are less able to remember a list of numbers or words that they had recently seen. But their long-term memory was not impaired and they could still remember data they had learned while not high. Some studies have shown that short term memory can be impaired in long term users while they were not high.

The Takeaway

Most studies show that young adults who smoke regularly do worse in terms of general intelligence that those who do not smoke or who smoke infrequently. This is known as an association. Young adults who smoke frequently are also more likely to come from a lower socio-economic background, so it is impossible to know if there is a definitive link between cannabis consumption and lower IQ in young adults through this method. But it is perhaps best to err on the side of caution. Over indulgence is never a good thing and it might not be a good idea for young adults to smoke every single day at such a crucial stage in their development. This goes for adults too, and while cannabis might have many benefits, moderation is nearly always the best option.


Geez, there seem to be a lot of people named Ann who write marijuana blogs. Well, that’s my name too, and when I asked my mom why she decided to give me such a mundane label she explained that the name Ann meant God has favored me. My name took on a whole new significance and I no longer thought it boring. And God has favored me – he gave me the gift of the gab and he smiled his approval when I decided to move to San Francisco. I love this city, I love the people, and most of all I love writing about marijuana.

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