Coffee, a popular morning beverage to kick start the day, is often consumed for alertness. But some researchers believe drinking coffee in the long-term can also change the brain.
For some time, research on both animals and humans have suggested that long-term consumption of caffeine improves learning and intelligence by fine-tuning neurons for efficient neural activity and increasing the number of states the brain can have.
Bees that consumed caffeine are able to remember a previously learned floral scent.
People who took caffeine straight after learning scored higher marks in discrimination tasks.
Caffeine’s possible relationship with learning and cognition may also be why coffee drinkers have been shown time and time again to have a lower risk of developing cognitive decline and neurodegenerative diseases including Alzheimer’s and Parkinson’s disease.
What exactly is caffeine doing to our brains to improve learning and reduce cognitive decline and what are its long-term effects?
Studies on animals may provide us with an answer.
Coffee Switches Learning Genes “On” While Turning Metabolism Genes “Off”
Some research shows caffeine may improve the formation of long-term memory by enhancing and fine-tuning the learning process in the brain.
French researchers experimented with caffeine’s effect on learning by making mice used to being exposed to learning enviroments navigate through a water maze.
One group of these mice drank normal water, while the other group drank water laced with caffeine at a concentration equivalent to moderate intake in humans.
Upon examining the brains of the mice that navigated the maze, researchers found both groups of mice turned “on” learning genes and turned “off” genes that were not involved in learning, including genes that took part in the metabolism of fats.
However, the mice that consumed caffeine daily learned to navigate several places faster and regulated significantly more genes than the mice that only drank water. Caffeine-drinking mice regulated five times more genes than the other group which only regulated 209 genes.
This effect persisted for over two-weeks, demonstrating a long-term change in the brain.
Furthermore, the caffeine group turned on significantly more genes that can improve learning and connectivity between neurons and switched off more genes related to the metabolism of fat and amides as compared to the mice that drank plain water.
Scientific research talks of the effects of nature and nurture. In genetics, “nature” is the DNA you inherit from your parents, and “nurture” is the environmental factors that can control how your genes are expressed.
Genes can be switched “on” or “off” through molecules called epigenetic modifiers that stick to DNA and can be controlled by environmental factors such as diet, behavior, and mood, among others.
Epigenetic modifiers include methyl groups that turn off genes and acetyl groups that usually turn on genes.
If a gene is turned off, the DNA will be tightly wrapped and the information that it encodes will become very difficult to access or read. Genes that are turned on however, remain loose, enabling easy reading of its information which will then be translated into cellular processes of metabolism.
Therefore, depending on an individual’s behavior and diet, different genes enabling different processes will be turned on.
In the case of mice learning something new, those that drank caffeine laced water had an enhanced epigenetic process in their learning and connectivity genes than mice that only drank water, suggesting an enhanced learning experience.
Researchers experimented further to see if caffeine had the same effect on mice that were not in a learning environment.
Curiously, caffeine had the opposite effect on sedentary mice.
Sedentary mice forced to learn and navigate a water maze suppressed learning genes and activated metabolism, suggesting a reinforcement of what they were used to, which was no exercise and no learning.
However, this enhancement was increased in the genes of the sedentary mice that drank caffeine, with even greater suppression of learning processes and so on.
The researchers concluded that caffeine may be offering a better “encoding of experience-related events.”
For those where learning is intrinsic, caffeine accelerated the learning process, but for those with a sedentary lifestyle, caffeine reinforced genes in the opposite direction.
These findings open up the possibility that caffeine might be used to enhance other processes such as a more efficient encoding of processes in exercise.
Caffeine, Learning and Brain Diseases
Knowledge and caffeine are both major protective factors against diseases of cognitive-decline such as Alzheimer’s disease and dementia.
The general understanding is that those who know more and have more cognitive abilities progress more slowly in cognitive-declining diseases.
However, studies have shown caffeine may play a more intrinsic role in preventing neurodegenerative and cognitive-declining diseases.
For a maximum health benefit, the daily intake is generally capped at 400 mg of caffeine a day—the equivalent of 3 to 4 cups of coffee.
Some studies show drinking up to 400 mg, reduced long-term risk by up to 60 percent in Alzheimer’s and Parkinson’s disease when compared to low or non-caffeine consumers.
Alzheimer’s Disease and Caffeine
Alzheimer’s is a progressive and irreversible neurodegenerative disease that leads to cognitive, behavioral, and memory decline.
In late stages, patients will gradually lose both their involuntary and voluntary motor control.
These symptoms may be explained by the areas of the brain most affected by Alzheimer’s which include the hippocampus, a seahorse structure deep in the brain, and the neocortex, the outer layer of the brain.
The hippocampus forms and stores long-term memory, while the neocortex is responsible for voluntary movements, decisions, emotions, and perception.
In Alzheimer’s, in the hippocampus and neocortex, patients will generally develop plaque deposits made up of amyloid-beta protein plaques outside cells, an accumulation of tau protein fibrous tangles inside the neurons, and neuronal loss.
However, animal studies have shown caffeine reduces the hallmark amyloid-beta plaques in Alzheimer’s disease.
In rats, caffeine can reduce plaques up to 60 and 50 percent in the hippocampus and the neocortex.
Loss of a protein called protein kinase A (PKA) is also a frequent factor in Alzheimer’s disease and other neurodegenerative diseases.
Normal levels of PKA protect against Alzheimer’s as the protein reduces the formation of plaques by preventing the accumulation of plaque-forming proteins.
In mice with Alzheimer’s-like plaques, caffeine can raise levels of PKA back to normal and reduce plaques in the brain.
As an antioxidant, caffeine also reduces oxidative stress by neutralizing the actions of reactive oxygen species, often caused by the breakdown of fats or other cellular processes.
Reactive oxygen species can injure neurons and cause cell death but their neutralization due to the action of caffeine reduces and prevents neuronal loss.
Parkinson’s is another neurodegenerative disease that caffeine can protect against.
Dopamine is a neurotransmitter which acts as a switch to turn on neurons.
In Parkinson’s, however, dopamine-producing neurons in the substantia nigra and the striatum, two important structures in the control of movement, are slowly destroyed.
Parkinson’s patients often exhibit bradykinesia (slowness of movement), rigidity, and postural instability.
However, caffeine may be able to reduce damage and death of dopamine-producing neurons as it can inhibit adenosine receptors, some of which are responsible for inducing inflammation and brain cell injury that can damage dopamine-producing neurons.
Tea or Coffee?
Though coffee is the most common and preferred beverage for caffeine consumption, it isn’t the only natural source of this interesting chemical.
Depending on the brewing method and the type of coffee used, the caffeine content can vary (pdf).
Espresso has the most concentrated caffeine with 0.6 to 3.3 mg per millimeter. Boiled or filtered coffee has a caffeine concentration of 0.7 to 1.1 mg/ml, and instant coffee generally has a concentration of 0.2 to 0.6 mg/ml.
Arabica coffee is the most widely consumed but Robusta has almost twice as high caffeine content.
Apart from caffeine, coffee is also rich in antioxidants such as hydroxycinnamic acids (70 to 350 mg) and polyphenols (35 mg), both of which prevent the development of diseases caused by chronic inflammation, including cancer and diabetes.
The drink also contains a small serving of minerals including potassium, magnesium, and phosphorus.
Despite all of its positive effects, coffee should be consumed only in moderation with no more than 4 cups a day—400 mg of caffeine—with a limit of 200 mg (two shots) per drink. Caffeine may also not be for everyone as those that are sensitive to it may experience palpitiatons, high blood pressure and restlessness.
If you are sensitive to caffeine or coffee is just not your thing, tea is a viable alternative for a healthy, lower caffeine-content drink.
Dried tea contains the highest caffeine content; 3.5 percent of tea leaves are caffeine, as compared to 1.1 to 2.2 percent in coffee beans.
However, since more coffee beans are used per serving, a single serving of tea will rarely contain more that 100 mg of caffeine.
Shortening the brewing time and lowering brewing temperature of tea will reduce the amount of caffeine. The hotter the tea and the longer it is brewed, the greater the caffeine content it will have.
Brewing black tea for 3 minutes will generally halve the content to 47 mg.
Matcha tea, the powdered form of dried green tea, is also a highly caffeinated tea that provides 35 mg of caffeine per half-teaspoon (1 g) serving.
Green tea and white tea are weaker than matcha and black tea and have a subtler taste compared to the characteristic sharp tang in black tea.
These drinks are generally brewed at lower temperatures of up to 180 F (82 C) which results in 20 to 45 mg of caffeine per serving for matcha and 6 to 60 mg for green tea.
Herbal teas such as chamomile, lavender, and jasmine contain no caffeine, though some drinks do report negligible caffeine content.
Like coffee, tea is also a rich source of antioxidants. Tea leaves are abundant in polyphenols, which maintain gut health and have antiaging actions.
Minerals such as potassium, calcium, and magnesium are also present in small servings of tea.