We know what caffeine does to our brains: New studies reveal surprising connections

Coffee is part of everyday life. Some can’t imagine a morning without it, others use it as a source of energy during the day. There is talk about the various negatives and benefits of caffeine, but what real effect does it have on your brain? The latest studies reveal if your health is at risk.

Coffee affects the structure of the brain

Coffee has been shown to affect a person’s health. Research published in the journal Cerebral Cortex revealed that caffeine can do much more than just stimulate alertness, focus and provide energy. It also causes serious changes to the structure of the brain. In fact, regular coffee drinking reduces the amount of grey matter in the hippocampus, which is responsible for memory and learning ability. This effect was observed in study participants who were given caffeine for a long period of time. However, the changes in the brain are not permanent; after a few days, the brain structure returned to its original state.

The brain is also affected during sleep

In 2024, a team of scientists looked at the effect of caffeine on the brain during sleep and discovered that it increases the “criticality” of the brain. “Criticality is a happy medium where brain activity is organized and flexible. In this state, the brain functions optimally: it can process information efficiently, adapt quickly, learn and make agile decisions,” described Karim Jerbi, one of the authors.

As the study authors note, caffeine stimulates the brain and puts it in a critical state during which it is more alert, vigilant and responsive. However, if these aspects are also promoted during sleep, the brain is unable to properly relax or regenerate overnight. They also pointed to changes in electrical rhythms. Caffeine attenuated the theta and alpha waves, which are associated with deep and restorative sleep, while stimulating the activity of beta waves that take place during wakefulness. The effects of caffeine were most pronounced in young people aged 20 to 27 years.

Lower risk of neurodegenerative diseases

Other research has linked coffee consumption to a lower risk of neurodegenerative diseases, particularly Alzheimer’s and Parkinson’s disease. The study revealed that coffee drinkers had a 34 percent lower risk of developing Alzheimer’s disease compared to people who don’t drink coffee at all. At the same time, the likelihood of developing Parkinson’s disease was reduced by 37 percent.

Experts have also found that caffeine is able to slow the development of some diseases, even early stage Alzheimer’s disease. One of the most prominent features of these diseases is oxidative stress. “Both Alzheimer’s and Parkinson’s, as well as other neurological diseases, are characterised by oxidative stress in the brain. It is caused by unstable molecules, so-called free radicals, which cause DNA damage and cell death. Caffeine probably acts as a powerful antioxidant to counteract oxidative stress, “said Ralph Martins, professor of neurobiology at Macquarie University in Australia.

Effect on mood and alertness

Caffeine has a significant effect on the central nervous system and stimulates the brain in several ways. It blocks adenosine receptors, a substance that induces fatigue in you. But when caffeine prevents it from binding in the brain, you feel more energetic and alert. It also increases the release of certain neurotransmitters, such as dopamine. These affect mood and reaction speed. On the other hand, excessive consumption can lead to depressive states. “In high doses, it can also cause anxiety and keep you awake, ” Ralph Martins added.

How much coffee to drink?

Coffee dosage is very important, whether in the short term or long term. To prevent neurodegenerative diseases and other problems, you should drink between one and four cups a day. If your body is sensitive to caffeine, the effects can be much stronger, so you need to watch the amount of coffee you drink.