A new study claims caffeine enhances long-term memory.
Caffeine is the world’s most used drug with 90% of us consuming it on a daily basis. We are all too familiar with the claims that caffeine plays a role in the prevention of Alzheimer’s disease, the boosting of the immune system and the promotion of cardiac arrhythmia. The most recent news coverage looks at the effects of caffeine on long-term memory retention. One headline even went so far as to suggest that downing a shot of espresso straight after revision will help you pass your exams.
Past studies have shown that caffeine acts as a cognitive enhancer through its effects on mood, arousal and concentration without affecting long-term memory. However, the majority of these studies administered caffeine before learning and memory tasks. This makes it difficult to assess whether caffeine enhances memory by simply perking up the user or by directly affecting the laying down of memories.
Last week, a study published in Nature Neuroscience claims to have shown that caffeine enhances memory performance in a learning task. The research team, based at John Hopkins University in Maryland, recruited 160 participants who consume caffeine infrequently. All participants were asked to study images of objects before consuming either a pill containing 200 mg caffeine or a placebo. The following day they studied another set of images and had to determine which images were the same (‘targets’) or similar (‘lures’) to those of the previous day or entirely novel (‘foils’).
In comparison to the non-caffeinated group, the caffeinated group demonstrated a better ability to recognise the similar images as ‘lures’. Basic recognition ability, represented by the ability to recognise the ‘targets’ and ‘foils’, was unchanged between groups. It would of course be more impressive if this basic ability was enhanced, as highlighted by Dr Anders Sandberg, a Research Fellow at the University of Oxford: “We are too good at recognition memory: it is much easier to tell whether you have just seen something before than recall all the details. This is why the lures were used. It might be that doing the same experiment with recall might show a different effect”.
Thus, stating that caffeine enhances long-term memories is not entirely true; it does not help you remember all past events. Dr Ashok Jansari, a Reader in Cognitive Neuropsychology at the University of East London, explains “it is not necessarily an overall effect of remembering everything better. I would describe it as caffeine seems to sharpen the way you lay down memory traces so that you can tell later on whether your memory is correct or not.” In essence, caffeine may just enhance memory in a very specific way or it is possible that, due to the small number of participants, this is just a chance finding. As well as replicating this study, the authors should include participants who frequently consume caffeine as the apparent effects on memory here may be different or absent altogether.
The benefits of coffee
The beneficial effects of caffeine appear to plateau at 200 mg. This is equivalent to a large cup of coffee. So more is not necessarily better. The lead author of the study warns “caffeine can have side effects like jitteriness and anxiety in some people. The benefits have to be weighed against the risks”. The UK’s health service, the NHS, even published a report on their website to highlight that this hype is just another example of the media making dubious claims about a study’s findings. The NHS suggests “if you do have a big exam coming up, we would recommend that you stick to plain old tap water instead”.
It would certainly be more desirable to improve our ability to recall names or facts rather than simply recognise familiar faces or objects. Having a cup o’joy may not provide that desired cup o’memory, but one thing that will, is sleep. So lay off the coffee before bed!
Borota D, Murray E, Keceli G, Chang A, Watabe JM, Ly M, Toscano JP, & Yassa MA (2014). Post-study caffeine administration enhances memory consolidation in humans. Nature neuroscience PMID: 24413697