Many People Look at Many Other Looks at Other People Who May Have Been Drinking Coffee and Thinking

The mystery of whether drinking coffee affects people’s minds is still mysterious, thanks to the results of a new, complex academic study of many old, complex academic studies:

Habitual coffee consumption and cognitive function: a Mendelian randomization meta-analysis in up to 415,530 participants,” Ang Zhou, Amy E. Taylor, Ville Karhunen, et al., Scientific Reports, epub 2018. The large team (28 co-authors) reports:

“Coffee’s long-term effect on cognitive function remains unclear with studies suggesting both benefits and adverse effects. We used Mendelian randomization to investigate the causal relationship between habitual coffee consumption and cognitive function in mid- to later life. This included up to 415,530 participants and 300,760 coffee drinkers from 10 meta-analysed European ancestry cohorts. In each cohort, composite cognitive scores that capture global cognition and memory were computed using available tests.”

The people considered to have been drinking coffee may not all have been drinking coffee. The study explains:

“A genetic score derived using CYP1A1/2 (rs2472297) and AHR (rs6968865) was chosen as a proxy for habitual coffee consumption…. Despite the power to detect very small effects, our meta-analysis provided no evidence for causal long-term effects of habitual coffee consumption on global cognition or memory.”

Were the Coffee-Drinkers Coffee-Drinkers?

Part of the same team of researchers did an earlier study on the very question of whether many people thought to have been drinking coffee may have been drinking coffee. They concluded that yes, many people thought to have been drinking coffee may have been drinking coffee. That study is:

Phenotype refinement strengthens the association of AHR and CYP1A1 genotype with caffeine consumption,” George McMahon, Amy E. Taylor, George Davey Smith, and Marcus R. Munafo, PloS One, vol. 9, no. 7, 2014, e103448. The authors report:

“Two genetic loci, one in the cytochrome P450 1A1 (CYP1A1) and 1A2 (CYP1A2) gene region (rs2472297) and one near the aryl-hydrocarbon receptor (AHR) gene (rs6968865), have been associated with habitual caffeine consumption…. We used data from between 4,460 and 7,520 women in the Avon Longitudinal Study of Parents and Children, a longitudinal birth cohort based in the United Kingdom. Self-report data on coffee, tea and cola consumption (including consumption of decaffeinated drinks) were available at multiple time points. Both genotypes were individually associated with total caffeine consumption, and with coffee and tea consumption.”

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