Forgetfulness is normal in humans

How much forgetfulness is normal?

Where are the keys again? What was the name of this ..., uh, the thing? ”Mental dropouts like these are likely to occur quite frequently in a society that is fast, overloaded with information and aging at the same time. The human memory is a unique, but also a fragile miracle: Overtiredness, distraction or even a few glasses too many can be enough and it leaves you in the lurch.

Age makes you more prone to such dropouts. The brain starts to degrade slowly from the early thirties. It can indeed learn for a lifetime and thus continue to function at a high level for decades. But from around 50 onwards, the pace of thought and mental reserves decrease so much that the aforementioned disruptive factors are less well compensated. This is particularly noticeable for memory functions, as they are practically distributed and networked over the entire brain.

However, some illnesses can accelerate the decline in mental resilience. "Anyone who has persistent memory problems that also affect their work and even everyday life should have them clarified," advises Professor Thomas Duning, senior neurologist and dementia specialist at the University Hospital in Münster. If the problem is recognized in good time, it can possibly also be rectified - especially in the case of certain metabolic disorders or inflammatory diseases of the brain, which can also affect younger people.

Blood flow problems in the brain

Age-related illnesses such as high blood pressure or diabetes damage the small vessels deep down in the brain, where mainly nerve tracts run. Chronic circulatory disorders in this area make thinking awkward and slow, which also has an unfavorable effect on memory - a process that can lead to what is known as vascular dementia.

A good therapy for vascular diseases can protect against this. It is even better to take preventive action through a healthy lifestyle. British psychiatrists conclude in a recent report in The Lancet that 40 percent of all dementias could be prevented by avoiding certain risks.

The experts name smoking, excessive alcohol consumption, high blood pressure, obesity and lack of exercise as negative influences. Conversely, several studies have shown that physical activity, for example, also keeps the head fit. The link is obvious: exercise increases blood flow to the brain, lowers high blood pressure, and helps burn excessive calories.

Mental activities also keep the brain going: things that the nervous system trains regularly, it can do better and longer. And a high level of education evidently helps to have more reserves in order to compensate for a decline in intellectual strength.

But whether brain jogging is good for increasing mental capacities is a matter of dispute. Studies have shown lasting training effects in healthy volunteers. However, these are mainly limited to the skills practiced - for example memorizing numbers. Other cognitive performance could not be improved in this way, at most indirectly through the improvement of the ability to concentrate. "The formation of memory is about continuously running adaptation effects, which the brain is capable of in principle throughout life," says neuroscientist Dr. Matthias Nau from the University of Trondheim in Norway.

Unimportant things are sorted out

This is probably also due to the fact that the brain always works economically. In contrast to a hard drive, it does not store everything without criticism, but instead filters, updates and cleans up constantly. “Forgetting is also an active process of memory. In addition, our brain is constantly recombining existing memory contents and is thus able to cope with current requirements, ”says Nau.

A study by Swedish and Finnish researchers in 2019 showed that certain learning strategies improve memory performance - but only at the beginning: once the strategy is anchored, memory no longer increases. The scientists highlighted the function of the so-called working memory. These are nerve cell associations in the frontal lobe, where attention and planning actions are also controlled.

Working memory holds information for a few moments as long as it attracts special attention. This makes it possible to carry out actions sensibly - for example, going to the refrigerator to get milk without forgetting the destination on the way. Whether such an event is remembered years later, whether it gets into long-term memory, depends on other structures.

The so-called hippocampus in the temporal lobe organizes incoming information and forwards it to the relevant memory in the entire cerebral cortex. It sorts impulses from the short-term memories of the frontal lobe and transfers them to long-term memory when they are strong or significant enough - for example, when you arrive at the refrigerator and the milk bottle falls on your foot so that you cannot walk properly for three weeks. In addition to emotional amplifiers, the hippocampus also activates repetition - i.e. learning. If stimuli are offered to him often enough, he makes connections to long-term storage.

Sleep for a fit mind

The hippocampus does this particularly well during sleep. In experiments it could be shown how the brain structure recapitulates previously presented stimulus patterns, so to speak, overnight. Sufficient sleep not only rests the mind, but actively leads to a good memory.

Damage to the hippocampus or its connections usually has serious consequences. Severe amnesias can result: states in which no new information can be saved. Inflammation of the brain, chronic alcoholism or even strokes can cause this.

In Alzheimer's disease, the hippocampus region becomes stunted in the early stages. The patient's memory and spatial orientation are therefore already reduced when the robust old memory, part of the long-term memory, is still sufficient to master everyday routines. "In the course of the process, however, other areas of the cerebral cortex are affected, so that biographical knowledge and practical skills are also lost," says Duning.

But even in the case of such an incurable brain disease, promoted mental health would help, according to the neurologist: "The higher the capacity and the ability to compensate the brain, the longer the sick can lead their lives independently."