Friday 14 March 2014

Caffeine and Memory

I have a great fondness for my morning cup of coffee.  I'm pretty happy about my second morning cup of coffee, too.  Although my children like to taunt me about having an addiction, they also know better than to bother me before my first cup of joe in the morning.  And occasionally I indulge in an afternoon pick-me-up, yet another steaming mug.  Coffee wakes me up, gets me going, makes me alert and creative.  Once, in a foolish fit of well-meaning, I gave up coffee for a year.  It was the most dull, flat, uninspired year of my life.  I’ll keep the coffee, thanks.

And so it always pleases me to read about positive effects of caffeine.  The February 2014 issue of Nature Neuroscience includes an article showing that caffeine increases memory consolidation.  Caffeine has been shown in the past to increase alertness and attention, but a proven role in memory in humans has been lacking. 

This recent study, authored by Borota et al. out of Johns Hopkins University, had subjects study pictures of objects, asking them to consider whether each one would be used indoors or outdoors.  Afterwards, they were either given 200 mg of caffeine, or a placebo.  The next day, the people came back to the lab and were shown another series of pictures.  Some pictures were the same ones they had seen the previous day, some were completely new, and some were “lure” pictures, similar to those seen on the previous day, but not identical.  The subjects had to try to remember what they had seen the previous day, and say whether each picture was new, old or similar.  The researchers found that people were pretty good at distinguishing new from old pictures, but the tricky part of the task was the lure pictures.  People who had taken the caffeine pills were better at recognizing these pictures as similar but not the same as those they had previously seen.

Memory processes go through several stages.  The first is encoding, when we get new information and store it in our brain, laying down a memory trace.  The next step is consolidation, in which memories become resistant to interference from competing memories, and become strengthened.  In a research setting, this is usually seen as better performance on a memory task.  Some consolidation of memories can occur while we’re awake, but there is a large body of evidence showing that memory consolidation during sleep is critical for strengthening memories.  The last memory process used by the subjects in this research study is memory retrieval, where memories are pulled out for use in a memory task.

Because in this study the caffeine was administered after the subjects had studied the pictures for the first time, we cannot tell anything about the effect of caffeine on memory encoding (although other studies have not shown any real effect).  And saliva tests showed that there was no residual caffeine in the subjects’ systems at the time of memory testing, so this study doesn’t implicate caffeine in memory retrieval either.  This study shows that caffeine boosts memory consolidation.  Excellent!  I think I’ll go and make myself another cup.

Borota, D., Murray, E., Keceli, G., Chang, A., Watabe, J.M., Ly, M., Toscano, J.P., and Yassa, M.A. (2014). Post-study caffeine administration enhances memory consolidation in humans. Nature Neuroscience 17:201-203.