Sunday, March 7, 2010

The Perils of Fair-Weather Cocaine

The higher the temp, the higher the death rate.

As spring approaches, cocaine users might take note of further evidence of a connection between high ambient air temperatures and accidental overdoses.
This post was chosen as an Editor's Selection for
A study published recently in the journal Addiction used mortality data from the Office of the Chief Medical Examiner in New York City from 1990 to 2006 to determine the frequency of cocaine-related overdoses (itself an enterprise fraught with uncertainty and argument over listed causes of death).  The researchers cross-referenced the mortality data with temperature records from the National Oceanic and Atmospheric Association (NOAA).  

As reported in Addiction Journal, “accidental overdose deaths that were wholly or partly attributable to cocaine use rose significantly as the weekly ambient temperature passed 24 degrees Celsius [75 degrees F].

Previous research, the authors write, had indicated that significantly higher temperatures—in the high 80s F--were required before cocaine mortality rates showed an increase. The researchers said they did not detect a corresponding rise in other types of drug overdoses during days over 75 degrees.

What is the mechanism connecting temperature to cocaine overdose? Cocaine intoxication raises core body temperature. Overheated cocaine users risk overdosing on smaller doses of the drug because their bodies are already under the strain of mild hyperthermia, or increased body temperature.

Specifically, the researchers from the University of Michigan and elsewhere found that above 75 degrees, there were 0.25 more drug overdoses per 1,000,000 residents per week for every two-degree rise in temperature, according to Addiction Journal. Applied to New York City, these numbers suggest and additional two cocaine deaths per week for every two degrees increase in average temperature over 75.

Lead author Dr. Amy Bohnert of the University of Michigan Medical School said in a press release that cocaine users are already “at a high risk of negative health outcomes and need public health attention, particularly when the weather is warm.”  During the study period, New York City had average weekly temperatures in the >24 C range roughly seven weeks per year.

The idea is quite plausible, given that ambient air temperature can affect many other metabolic processes.  Earlier investigations led to the discovery of a fairly well established diurnal AND seasonal variation for measurements of blood pressure. Researchers at Emory University data-mined 2 million  electronic records of participating patients and discovered that the odds of having high blood pressure were lowest during the morning, and generally increased throughout the day. Seasonally, high blood pressure occurred more often in winter, and was at its lowest in the summer. 

Bohnert, A., Prescott, M., Vlahov, D., Tardiff, K., & Galea, S. (2010). Ambient temperature and risk of death from accidental drug overdose in New York City, 1990-2006 Addiction DOI: 10.1111/j.1360-0443.2009.02887.x


lee said...

I'm wondering, first if you are talking about cocaine in the powdered state or crack cocaine or both- and secondly, if the rise in atmospheric temp + the temp of cocaine smoked wouldn't be even more dramatic. The last part about jhigh blood pressure - if it's more pronounced in the winter. wouldn't that negate your thesis?

Dirk Hanson said...

All good questions. I don't know if they broke out powdered and crack cocaine in the mortality stats. Secondly, I agree that the increase seems pretty low, considering. And finally, I threw in the data on high blood pressure in winter precisely because it doesn't seem to fit the thesis. It seemed odd to me and I didn't have an explanation. I thought maybe some of my sharp-eyed readers would comment on this.

Neuroskeptic said...

Interesting. There's also quite a lot of data showing that MDMA toxicity is also temperature-related...

Dirk Hanson said...

...And I can't help wondering whether the same is true of meth...

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