Temporary short term memory loss from cannabis question

[DexterMeth]

Does anyone here (or humans in general), know why and how/the mechanism of action of why people have an impaired memory (generally speaking, you all know what I mean) from ingesting cannabis? This is a very serious question. I was thinking about posting it in the ADD forum because there are some obvious rocket scientists over there, but since I have no clue how easy or hard a question this is to answer, I thought I'd just post it here first; mod(s) move accordingly if need be. Thank you.

 

[Chainer]

The hippocampus contains a large abundance of cannabinoid receptors. It is no wonder that 9-THC would greatly affect this area of the brain due to this fact. However, there is more than one pathway through which 9-THC affects the hippocampus, which lead one to believe that memory loss undisputedly attributable to the neurotoxicity of 9-THC.

A well-known pathway in this area of neurotoxicity is the arachidonic pathway. As mentioned previously 9-THC induces the release of arachidonic acid through the PLA2 pathway. This increase in arachidonic acid will then activate the COX pathway and increase the activation of ROS. Once ROS is activated the peroxidation of the various lipids, proteins and DNA will cause the break down of the cell, and eventually lead to cell death. On a side note an experiment was done to see the effects of arachidonic acid on cultured hippocampal neurons in rats. Within 24 hours of application of arachidonic acid to the cultured cells 100ell death was observed. This however was not an accurate model because the application of arachidonic acid in this manner is not likely the same as that caused by the activation of PLA2 (Chan et al 1998). In the same experiment it was also found that vitamin E or aspirin protects the cells from any sort of neurotoxicity in regards to this pathway. This pathway is thought to be the main cause of cell death within the hippocampus, and therefore it is a good reason to believe that marijuana ultimately causes short-term memory loss.

In addition to this, marijuana has also been known to interfere with LTP. This is easily shown since 9-THC inhibits the influx of calcium through the inhibition of N- and Q-type calcium channels. In the hippocampus this leads to a lack of LTP. A loss of LTP in the hippocampus where memories are formed would prove to be an accurate assessment of the fact that marijuana causes loss of short-term memory (Diana et al 1998). In fact evidence has been found that 9-THC destroys short-term memory (Heyser, 1993)

 

[gezgin]

Interesting. How temporary can this short term memory loss be? I remember smoking one of the legal analogues of THC for a whole year, day in and day out, and that wrecked my memory, but recovered after a few months when I stopped. I think the legal analogues are more unhealthy than good ol' weed.

 

[d00ber]

there are unforseen outcomes and interactions with new drugs, analogues.
but there are way to many other things in weed that i would worry about b4 delta
wont suck to bad if your memory is shot, that way you'll forget you have lung cancer.

 

[Chainer]

Interesting. How temporary can this short term memory loss be? I remember smoking one of the legal analogues of THC for a whole year, day in and day out, and that wrecked my memory, but recovered after a few months when I stopped. I think the legal analogues are more unhealthy than good ol' weed.

This is probably very true. I noticeably have a worse short term memory after smoking daily for a week. However, after a week of none use, I feel good as new. A month or two later, I feel like a complete non smoker.

 

[leet]

This is probably very true. I noticeably have a worse short term memory after smoking daily for a week. However, after a week of none use, I feel good as new. A month or two later, I feel like a complete non smoker.

how can yuo be sure yuo remember what that really feels like?

 

[Cheshire Squirrel]

The hippocampus contains a large abundance of cannabinoid receptors. It is no wonder that 9-THC would greatly affect this area of the brain due to this fact. However, there is more than one pathway through which 9-THC affects the hippocampus, which lead one to believe that memory loss undisputedly attributable to the neurotoxicity of 9-THC.

A well-known pathway in this area of neurotoxicity is the arachidonic pathway. As mentioned previously 9-THC induces the release of arachidonic acid through the PLA2 pathway. This increase in arachidonic acid will then activate the COX pathway and increase the activation of ROS. Once ROS is activated the peroxidation of the various lipids, proteins and DNA will cause the break down of the cell, and eventually lead to cell death. On a side note an experiment was done to see the effects of arachidonic acid on cultured hippocampal neurons in rats. Within 24 hours of application of arachidonic acid to the cultured cells 100ell death was observed. This however was not an accurate model because the application of arachidonic acid in this manner is not likely the same as that caused by the activation of PLA2 (Chan et al 1998). In the same experiment it was also found that vitamin E or aspirin protects the cells from any sort of neurotoxicity in regards to this pathway. This pathway is thought to be the main cause of cell death within the hippocampus, and therefore it is a good reason to believe that marijuana ultimately causes short-term memory loss.

In addition to this, marijuana has also been known to interfere with LTP. This is easily shown since 9-THC inhibits the influx of calcium through the inhibition of N- and Q-type calcium channels. In the hippocampus this leads to a lack of LTP. A loss of LTP in the hippocampus where memories are formed would prove to be an accurate assessment of the fact that marijuana causes loss of short-term memory (Diana et al 1998). In fact evidence has been found that 9-THC destroys short-term memory (Heyser, 1993)

Very interesting journals, especially in the rat studies. From what I understand, everything you've presented seems to be true, however replicating these experimental findings might now--in modernity--demonstrate something a bit different. I will admit my understanding of neuroscience and psychopharmacology, as well as general chemistry is quite limited, however the loss of short-term memory is quite an interesting comment to make. Wouldn't the more appropriate term be the disruption of short-term memory? I understand in other experimental cases (that unfortunately I no longer have the citation information on these journals) in rats, there was reported an almost temporarily hippocampal lesion post the onset of the high, and slowly diminished. Basically, pre-synaptic and post-synaptic neurons weren't engaged in normal-day exocytosis on the hippocampus--not many key neurotransmitters were being released (acetylcholine, norepinephrine, glutamate, etc.).

However, I'm curious, did the journals you mention use several treatment groups for the rats? A big mystery to myself is whether a frequent exposure to cannabinoids has any "plastic" effects on the brain, especially with the processing of 9-THC. I haven't read into much neuroscience journals in respect to in vivo human experiments, but other psychological journals have demonstrated in frequent human users that in some people it wasn't so a lack of memory, but rather a decrease in response time. Though, I doubt much objective conclusions can be drawn from that. Also, when you mention cell death are you referring to apoptosis or necrosis?

Sorry if I'm reviving a dead thread here, but I'm quite curious about a few of things. Also, my understanding of neurotoxicity might be still premature, but what exactly do you mean by "the neurotoxicity of 9-THC"?

 

[sekio]

I was under the impression that oxidative stress is something that you just can't prevent and is a normal part of metabolism, also that d9-THC was neuroprotective...

 

[F1n1shed]

^ ^
The way by which cannabis effects people is very complex, especially compared to other drugs. But don't be fooled by the neuro-protective bull shit, it may be in some ways. But don't think that smoking, will in any way 'help' your brain.