Saturday, October 07, 2006

Marijuana and Alzheimer disease progression

On August 9th, there was a study published online in Molecular Pharmaceutics by researchers from the Scripps Institute in California; the same day, Scripps posted a press release about the study.

It's a basic science study that employed modeling techniques and biochemical assays, finding that THC, marijuana's active ingredient, interferes with an enzyme that has been implicated in the formation of plaques in Alzheimer disease. From the press release:

"THC inhibits the enzyme acetylcholinesterase (AChE), which acts as a "molecular
chaperone" to accelerate the formation of amyloid plaque in the brains of Alzheimer victims. Although experts disagree on whether the presence of beta-amyloid plaques in those areas critical to memory and cognition is a symptom or cause, it remains a significant hallmark of the disease. With its strong inhibitory abilities, the study said, THC "may provide an improved therapeutic for Alzheimer's disease" that would treat "both the symptoms and progression" of the disease."
This week, the study was picked up by UPI (Google news search results retrieves ~50 articles in different media outlets) -- it caught the attention of Rush Limbaugh, who covered it in his radio show on Friday.

I don't think there's ever been an occasion where I've agreed with his opinions, and I hesitate even to link to this but for the sake of discussion, here's his take on potential conflict of interest and the role of peer review for this research:

"But who's to say that there aren't a bunch of dopers among the research team who want the stuff legalized and are using the cover of their protected status as "scientists" to make this claim? Now, I know that their studies have to be peer reviewed and all that, but who's to say that the people doing the peer review aren't also a bunch of dopers who can sick and tired of being told that what they're doing is illegal. I think that's behind the medical marijuana business and so forth, the legalization of that. I'm not commenting on whether it should be legal or not. I'm just suggesting there's obviously a push on to get this stuff mainstreamed, and we know that there are a lot of people who use the stuff who want it mainstream because they want to be able to access it freely and regularly."
While it's a pretty broad and inflammatory statement about the research (and having looked at the original article, seems questionable whether a non-scientist could do more than read the press release and the media commentary, so Limbaugh's statements likely aren't based on the actual research but on the distilled commentary), it does point out one of the biases that can creep into research -- an individual's interests and beliefs can't help but influence the generation of research hypotheses; it is logical that people pick topics and projects for which they feel passion and suspect may have significant impact on problems facing humanity. However, we hope, as consumers of research, that the peer review process examines the research techniques employed to examine these hypotheses to make sure that the process and the data aren't influenced by personal biases, and that the authors' don't overstate the implications of their research.

One clue that the media is hyping this story beyond the intentions of the original researchers - a LiveScience story on the study includes a quote from the lead researcher on the project, Kim Janda, which seems to present the research implications fairly conservatively: "We're not advocating smoking dope, but if we can make analogues of THC, it could play a role in treating Alzheimer's...It would be nice to do more animal studies along these lines."

I definitely can't claim to be an expert (even particularly well-informed) about the medical marijuana debate, but these links give more info:
- the Institute of Medicine published a report, "Marijuana and medicine: assessing the science base," in 1999
- a podcast from the Genetic Science Learning Center at the University of Utah
- Congressional Research Service: "Medical marijuana: review and analysis of federal and state policies"

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At 12:36 PM, Blogger Rachel said...

My understanding is that it's fairly difficult for researchers to even be allowed to conduct these kinds of studies due to the Schedule classification under current drug laws, so I think the area of research makes a difference in how many evangelical promoters you have among the researchers. I suppose this is somewhat linked to the issues of conflict of interest, such as whether people stand to make money off of the results. They do already have a synthetic version, Marinol, which is prescribed primarily to cancer patients. I imagine producing a synthetic pill is more profitable than allowing legalization of an existing product, so it's a bit of a two-way street.

At 1:55 PM, Blogger BeckyJ said...

A very good point. In one of the interviews and maybe in the actual paper too, the researcher points out that a synthetic version of the active compound may provide a useful therapeutic option (rather than advocating administration via smoking).

Another interesting example of researcher passion - researchers into therapeutic use of thalidomide since the publication of the birth defect data have faced quite a few challenges in both conducting the research and in advocating use for certain specific conditions (Crohn's etc) -- similar in some ways to one of the traditional controlled substances, there are very strict guidelines for prescribing and administering thalidomide to prevent fetal exposure (more via Wikipedia).


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