Caffeine may be decreasing gray matter in the brain, study suggests

(Courtesy of Bhabna Banerjee)

A recent study published in February by Yu-Shiuan Lin et al. has found that your daily cup of coffee may be decreasing the gray matter volume in your brain. Before you vow to never drink coffee again, let’s take a look at how the study was conducted and what its findings mean.

All 20 participants of the study were habitual coffee drinkers placed into one of two groups. In the treatment group, participants were instructed to ingest three 150mg caffeine pills for nine days at regular intervals. Whereas those in the placebo group ingested mannitol pills, a non-caffeinated substance, for the nine days. 

After having slept in the laboratory overnight, participants reverted to ingesting the pills of their respective conditions around the same times as they had previously. Working memory tests were performed every four hours during 13 hours of wakefulness. 

After participants completed both the pre-laboratory phase and in-laboratory phase, they switched into the opposite condition and repeated the process as quickly as 11 days later and up to a maximum of two months afterwards.

The first major finding was that caffeine intake led to a decrease in gray matter volume in the brain. The gray matter is responsible for the processing of information, and is involved in tasks such as muscle control, sensory perception, memory, emotions, speech, decision making, and self-control. Decreases were most prominent in the right medial temporal lobe in the brain, which includes the hippocampal region. 

To get some further ‘tea’ on the human brain in relation to the study’s findings, I sat down with Dr. Dale Stevens, an associate professor of neuropsychology and the director of the York MRI Facility.

According to Stevens, the medial temporal lobe is said to be more critical for “longer-term memory, encoding new memories, and retrieving old memories.” Stevens adds that though a reduction in gray matter volume is not generally a good sign, changes in gray matter volume at certain stages of human development are normal. 

“In general, we consider a nice, healthy brain to have lots of volume and lots of gray matter. That shrinkage or atrophy is typically not good. Gray matter volume reduction is one of the things we see in typical aging across lifespan. As you get older, gray matter volume goes down,” Stevens explains. 

The study also indicated that the caffeine intake led to poorer working memory performance based on the results of a series of working memory tests. According to Stevens, working memory is “your ability to hold information in conscious awareness for short periods of time.”

Stevens further notes that despite the decrease in working memory performance, the more caffeine the participants had in their system while in the caffeine condition, the better their working memory performance. 

He explains that the deprivation of caffeine for nine days while in the placebo condition causes the brain to perform poorly at the working memory tasks. This is because the participants are habitual caffeine users who are used to having caffeine in their system. When it is then reintroduced in the second phase, the brain’s functioning is essentially back to normal and thus, shows an increase in working memory performance.

Cassandra Fuoco, a third-year psychology student, admits that without her regular two cups of coffee per day, she feels the consequences.

“I usually feel pretty tired and as though I absolutely need the caffeine. Sometimes I get headaches. I can usually go without it but when I do, I’m not as energetic as I would be if I had coffee,” admits Fuoco.

She says that caffeine sometimes acts as a way to boost her energy levels after a sleepless night, that way she’ll be ready for the workday ahead of her.

When asked if we should be mindful of how much caffeine we drink based on the study’s results, Stevens warns to not make such a decision based solely on this study. He notes that the researchers discuss prior research, which has found mixed results on caffeine’s impacts on brain performance.

“There’s a bunch of studies arguing that lifelong or chronic caffeine over many years can have positive benefits — reduced rates of Alzheimers or increased cognitive performance, for example. But some other studies failed to find this effect. Across many studies, the implication is more often that coffee is good, has neuroprotective factors, or might boost cognition,” says Stevens.

For readers interested in prior research done on caffeine’s effects on brain performance, click here: Link 1, Link 2, Link 3, Link 4.

About the Author

By Laura Nuccitelli


Interested in becoming a contributor? Check out our Get Involved Page


Notify of
Inline Feedbacks
View all comments