Study on Marijuana, Male Reproductive Health Spawns Misleading Conclusion

By Denise A. Valenti via Multibriefs

Ever hopeful to report positive aspects related to marijuana use, writers often leave out key points. As an example, a report from a Boston-based publication had the following headline, "Harvard researchers link smoking marijuana with higher sperm concentration." It further concluded, "Experts say men who smoked marijuana have significantly higher concentrations of sperm than those who have never lit up."

The report describes the work with research participants, "…scientists collected 1,143 semen samples from 662 mostly college educated white men." What the media report left out was the description that appeared in the published research, "…This longitudinal study included 662 subfertile men."

The men observed in this study were already suffering from reproductive problems related to the men’s reduced chance of conceiving.

The definition of subfertile is as follows: "Infertility is defined as the failure to conceive after regular unprotected intercourse for two years in the absence of known reproductive pathology ... Causes include impaired semen quality, azoospermia, or inadequate coitus. Couples where the man is subfertile have a reduced chance of conceiving."

The researchers involved in this study do recommend further study on the topic. "These unexpected findings highlight how little we know about the reproductive health effects of marijuana, and in fact of the health effects of marijuana in general," said Jorge Chavarro, associate professor of nutrition and epidemiology at the Harvard T.H. Chan School of Public Health. "Our results need to be interpreted with caution and they highlight the need to further study the health effects of marijuana use."

The study found that over one-half of the group stated having used two joints at some point in their lives and only 11 percent defined themselves as current users of marijuana. It would not be appropriate to conclude that marijuana use is in anyway responsible for levels of testosterone, high or low, based on the information obtained.

This may be a disappointment to those who are searching for a positive impact of marijuana on male testosterone and reproductive potential. Other research has found negative consequences of marijuana use in this regard.

One study was very small with only 24 participants but found that cannabis use was associated with significantly lower sperm concentration. These findings can result in pre-conception paternal reproductive problems. Ironically, reproductive problems were main reasons for why the men were being seen in the other study, which found an increased level of sperm in men reporting to have used marijuana at some point.

And it is not just male use of marijuana that is influencing hormones and reproduction. The male’s maternal use of marijuana has been shown to have long-lasting consequences in animal models. While there do seem to be conflicting reports related to male reproduction and sperm count with marijuana use, the research seems to be stronger in identifying negative consequences.

Dr. Denise A. Valenti is a residency-trained, low-vision/blind-rehabilitation optometrist who has worked closely with sensory and cognitive impairment and the ability to safely drive as a clinical provider. Dr. Valenti provided direct clinical care for more than 25 years and currently is active in research and consultation related to vision, aging, neuroprocessing, cannabinoids, cognitive function and driving. She has additional education and expertise in the field of age-related neurodegenerative diseases with the emphasis on Parkinson's disease and Alzheimer's disease. She had been honored as the Alzheimer’s Disease Drug Discovery Foundation’s outstanding young researcher and was selected by the AARP as an exemplary gerontology scientist. Her research has included the study of imaging of retinal neural tissue using Optical Coherence Tomography (OCT) and functional assessment of neural processing in the visual system using Frequency Doubling Technology (FDT). The neurocognitive impact of cannabis is an active area of research as is the treatment potential for Alzheimer’s disease and Parkinson’s disease. She is the principal in the development of technology to detect impairment in the retina and lateral geniculate brain nuclei from cannabis consumption, Impairment Measurement: Marijuana and Driving (IMMAD). The company IMMAD provides education, services and technology for the responsible use of cannabis. Dr. Valenti lectures on marijuana, cannabis, cannabinoids and cognition both nationally and internationally.


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