Marijuana reduces the working memory

How cannabis affects working memory

02.03.2012

Numerous research points to the positive effects of cannabis in the treatment of serious diseases. For example, scientists from the University of Alberta in Canada have recently determined that the drug contained in the plant tetrahydrocannabinol (THC) the „classificatory loss of appetite“ reduce the incidence of cancer patients. The only drawback: Although the substance helps to relieve pain and stimulate the appetite again, but it simultaneously obscures the memory of patients. Now, researchers from the Canadian University of Ottawa are trying to eliminate side effects on working memory. They were already able to decipher why human working memory suffers from the THC's influence.

Thousands of years old healing medicine
For thousands of years marijuana has been used not only as an intoxicating remedy, but also as a medicinal herb of natural medicine. For some years, the interest in the versatile plant has also increased from the side of scientific medicine. Several studies pointed to the palliative and healing effects. The contained substance has been shown to relieve pain, minimize the adverse effects of chemotherapy in cancer, and has been shown to be helpful in the treatment of multiple sclerosis (MS) and AIDS. For example, MS patients benefit from the inhibition of spasticity, and in anorexia or cancer, cannabinoid drugs can rekindle hunger. On the other hand, after a longer period of regulation, those affected suffer from a decline in working memory, as confirmed by the present study.

Short notice of work tasks
The working memory is responsible for the temporary storage or alteration of information in the memory of the human brain. With the part of the brain area, for example, it is possible to accomplish short-term work tasks such as the temporary memorizing of telephone numbers or shopping slips. If the stored information is no longer needed, they are easily forgotten. This also creates space for new, timely memory tasks. With a computer, working memory also becomes „Clipboard or clipboard“ called. To eliminate the side effect, the researchers first have to decode the modes of action.

No effect on neurons
After several years of work, an international research consortium has succeeded in determining the context. They found that the substances in cannabis impaired the performance of short-term memory independently of the direct effect on the neurons. The reduction in performance is due to the influence of THC on the astrocytes. These cells serve as providers and supporters of the neurons. „Thus, evidence was provided that astrocytes directly affect working memory“, said Xia Zhang, an expert in neuroscience at the University of Ottawa. Before that, the world of researchers always assumed that the neurons themselves were influenced. But that the „Supporting cells in fact take a leading role, is the biggest discovery of our research“, says Zhang. „And that's just incredible!“

In the course of the study, the scientists observed rats and mice in the laboratory during various activities. One part of the animals was given artificial cannabinoids, another part got no substances injected. In a test run, the experimental animals had to cope with the so-called Morris water labyrinth. The mice were placed in a basin with cloudy water and had to find a pedestal under water. The first time the rodents first had to fathom the way there, the second time it worked much faster, because the working memory had saved the way there. The group of animals that were under the influence of THC, on the other hand, needed on average a longer period of time during the second round to find the platform under water. „Clearly recognizable was the negative impact on memory“, explain the researchers.

In the second experimental setup, the animals were given the drug, but lacked the receptor called „CB1R“. This is located on the cell membranes of the astrocytes. By doing so, the animals were immune to the specific brain performance against the negative effects. To secure the observation, the scientists also removed the CB1R receptor on the neurons. The result: „The animals still showed difficulties in finding the way in a timely manner“.

Therefore, the researchers summarize in the science magazine „Cell“, that the „Research revealed the typical effect of cannabis use caused by the activation of the CB1R receptor of astrocytes“. So now could be proven, „why consumers have a limited working memory during the period of intoxication.“

Hopes also for the study of Alzheimer's disease
As a next step, the research team will try to activate the receptors on the neurons while simultaneously deactivating those on the astrocytes. This could be successful because neurons have different receptors than astrocytes. If this could succeed, the active ingredients of the plant could be used for diseases without harmful side effects, without the patients having to suffer losses in their memory performance. The discovery could also provide new approaches to Alzheimer's research. In Alzheimer's disease, working memory is chronically reduced. Therefore, the scientists immediately formulate the next long-term goal: „The study results can be transferred to the mechanism in Alzheimer's?“ (Sb)

In addition to the report, read:
Makes cannabis consumption schizophrenic?
Cannabis reduces nerve pain
Cannabis: triggers psychosis?
Researchers recommend cannabis in cancer
Cannabis helps with bladder overactivity
Cannabis reduces nerve pain
Cannabis effective in ADHD?
Survey: Majority for cannabis use as medicine

Picture: Susanne Schmich