magazine issue 2 2007 / Issue 2

Brain Training: Practice Keeps You Fit

• written by Irene van Driel

Commercials on the importance of training your brain are nearly a daily occurrence nowadays. A world without Sudoku has almost become unthinkable. Not only puzzles like these, but also numerous specific internet exercise-sites and try-at-home packages are devoted to this phenomenon. This merchandise is usually accompanied by slogans saying something like: "improve cognitive ability and prevent the negative outcome of the aging brain". Just as physical exercise improves the shape of your body muscles, cognitive exercise should keep your brain in optimal form. Have the retailers of these products merely found a good catchphrase to sell their products, or do they actually have a point? In other words, can mental deterioration be prevented by cognitive exercise? It might come in handy to know some facts about the brain before starting to unravel the answer to this question.

Around the age of twenty your brain is fully mature. This adult brain then consists of billions of brain cells, the neurons, which make connections with each other and thereby form certain networks. Different networks are activated during different tasks. The adult brain has the ability to make new neurons throughout life. However, this so-called neuroregeneration is restricted to only certain areas in the brain. Nevertheless, the brain is capable of reorganizing connections during this period. As soon as the brain has reached its maximum volume, it will slowly decrease in size again. This is caused by loss of neurons and may eventually in part cause some of the mental problems of being old.

Alzheimer’s disease, probably the most well known disease related to the aging brain, can only be diagnosed with certainty after death. Autopsy results of several women showed that all had reached a severe stage of Alzheimer’s (Scarmeas and Stern, 2003). Interestingly, however, a quarter of these women had never shown any cognitive symptoms during their lives. This finding illustrates that a direct relationship between the severity of brain degradation and the influence on the functioning of an individual is unlikely. Consequently, the differences in outcome must arise from certain personal characteristics.

Several theories have tried to explain this phenomenon. One of these hypotheses describes the presence of a cognitive reserve varying in extent per individual (Scarmeas and Stern, 2003). The exact definition of this reserve is unclear. Some researchers define it as additional volume of the brain. In other words, persons with a higher brain volume should have extra capacity to cope with damage or neurodegeneration than people with smaller brain volumes. The more spare tissue, the more injuries can be ‘buffered’, so to speak. Others state that the reserve consists of relatively more flexible and efficient connections in the brain. When a situation requires additional capacity, people with a reserve are assumed to be able to switch to different networks from the ones originally used. This benefit of flexibility can be illustrated by the example of a mathematician. A professional mathematician is capable of solving a problem in several ways, while a less experienced person will probably only be able to think of one. In this light, experienced individuals can switch circuits at times when original ones become insufficient. The efficient component entails that fewer neurons are needed for ‘skilled’ information processing (Kelly and Garavan, 2005).

Additionally, Robertson and Murre (1999) suggest that the severity of the damage can influence which coping mechanisms are used. Deficits resulting from mild injuries can be fully recovered, severe damage can only be compensated for by other networks, and moderately damaged brains can follow either path. Accurate rehabilitation training should enable the brain in the latter stage to fully recover. Repeated activation of neurons may reestablish the broken connections. It depends, however, on the number of connections that are damaged within a network. As stated earlier, regeneration of new brain cells occurs only at specific brain sites. Changes in or strengthening of connections, on the other hand, can theoretically happen in all brain locations. Neurons attain a stronger and speedier connection through repeated synchronized stimulation (Robertson and Murre, 1999). This kind of stimulation happens in a healthy brain, for example, while you are learning a new football technique or knitting stitch. The brain is therefore said to possess ‘experience-dependent plasticity’ qualities. It is thus not impossible that cognitive training can have similar effects on the dynamics of the brain. Proper activation could, by this mechanism, increase your brain reserve.