The dangers of statistics.
British researchers report in the American Journal of Epidemiology,
A positive association was observed between ever (past or current) illicit drug use and cognitive functioning (β = 0.62, P < 0.001), although the effect size was small. At the population level, it does not appear that current illicit drug use is associated with impaired cognitive functioning in early middle age. However, the authors cannot exclude the possibility that some individuals and groups, such as those with heavier or more prolonged use, could be harmed.
The abstract is below.
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Alex Dregan* and Martin C. Gulliford
↵*Correspondence to Dr. Alex Dregan, Department of Primary Care and Public Health Sciences, School of Medicine, Capital House, 52 Weston Street, King’s College London, London SE1 3QD, United Kingdom (e-mail: alexandru.dregan@kcl.ac.uk).
Received June 2, 2011.
Accepted August 15, 2011.
Abstract
From March to July of 2011, the authors investigated the prospective association between illicit drug use and cognitive functioning during the midadult years. A total of 8,992 participants who were surveyed at 42 years of age in the National Child Development Study (1999–2000) were included. The authors analyzed data on 3 cognitive functioning measures (memory index, executive functioning index, and overall cognitive index) when the participants were 50 years of age (2008–2009). Illicit drug use at 42 years of age was based on self-reported current or past use of any of 12 illicit drugs. Multivariable regression analyses were performed to estimate the association between different illicit drug use measures at 42 years of age and cognitive functioning at 50 years of age. A positive association was observed between ever (past or current) illicit drug use and cognitive functioning (β = 0.62, P < 0.001), although the effect size was small. Even though there was no clear evidence against the null hypothesis, drug dependence (β = −0.27, P = 0.58) and long-term illicit drug use (β = −0.04, P = 0.87) tended to be negatively associated with cognitive functioning. At the population level, it does not appear that current illicit drug use is associated with impaired cognitive functioning in early middle age. However, the authors cannot exclude the possibility that some individuals and groups, such as those with heavier or more prolonged use, could be harmed.
Ah, Science has managed to latch onto the Cliff Claven “Buffalo” theory of beer.
It sounds significant since you would assume they would find drug use impares brain function by a large amount. Good to know past drug use isn’t making the population dumber. How else would the baby boomers be the current CEO’s and buisness owners? That generation should have ended up in the gutter, if drug use was a large factor on brain function.
Tom, reporting of Null results is important. Being specific about the type of null result, ie: huge variation, is also important. In fact, the honest nature of this abstract is a refreshing change. I do, however, look forward to the Guardian getting a hold of this and the fun headlines that may result. Most will not be so tongue-in-cheek as Mr Milloy
“Even though there was no clear evidence against the null hypothesis” they chose to report this as noteworthy. Evidently the illicit drug use may have included students in statistics classes.