The most important motivation for the early detection of ADHD is its effect on the children’s education. Children suffering from ADHD often show learning problems. Various methods and instruments are used to diagnose ADHD patients: Traditionally, questionnaires and interviews are mainly used for diagnosis. For children, neuropsychological tests are also offered, which allow statements to be made about the behaviour of the patients. In recent times – and this will be increasingly attempted in the future- biomarkers will be used to refine the diagnosis. The best experiences are currently being made with the EEG-related measuring method of event-related potentials. There is now hard evidence of their usefulness as supplementary markers for a better understanding of the correlations in individual cases.
There are several protocols for EEG-based tests, each of which examines a specific aspect of these patients’ problems. One of the earliest attempts was the extraction of frequency features from the resting EEG that are highly correlated with the patient group. Although there is a high degree of coherence across many studies that slow-rhythm EEG activity is observed in many children with ADHD, EEG frequencies are not able to provide enough specific information. Evoked potentials are more specific for statements on information processing in the patient’s processing brain. With the help of this method, many characteristics can be obtained from the human cognitive process. The basic premise of this protocol is that the human brain reacts in the same way to a certain input (image or sound) each time, and if this input is repeated, the output remains the same. By averaging over many of the patient’s responses under the same conditions, it is possible to reduce random noise from the output. In protocol used by the Brain and Trauma Foundation, different stimuli are used. Visual and auditory stimulation is of greater importance for specialists working with ADHD patients. This protocol includes four types of stimulation (see picture). The test person must react differently depending on the combination of the stimulus. For example, if the animal image is shown as the first stimulus and the plant as the second stimulus, the subject should not press the button.
However, the evoked potentials only partially reflect the real information processing. It has been shown that the response behaviour of the test subjects is significantly influenced by the previous tasks already processed. The influence is subconsciously caused by the working memory: If the memory is used differently, the response behaviour is considerably influenced by this. In addition to storage, the response behavior, e.g. delayed reactions, also influences the processing of the subsequent task. Our innovation takes place exactly here. For the sake of simplicity, we only investigate the effect of memory (from a systemic point of view). In other words, in addition to the stimulus pairs that need to be pressed differently (animal-animal, animal-plant, plant-plant-plant or plant-human/sound), the influence of the preceding processing on the subsequent processing is investigated and evaluated. For this purpose we have chosen a simple strategy. Using the above protocol, we have measured the influence of the preceding processing on the subsequent task. This shows how the brain transitions from one state to another.
The results were astonishing: there was a significant difference between the brain’s response to different previous tasks. In addition to the extended question, innovative mathematical concepts were developed which reflect the events in the brain in a differentiated way.
The different approaches to recording processes in the brain were also compared. It was found that the new method scores significantly better than the previous methods or at least complements them significantly.
Since all results of the Brain and Trauma Foundation’s research must ultimately benefit the patients, we are currently looking for ways to profitably integrate the currently still complex processing of information into the diagnosis process of individual patients. This should further improve the significance of neurobiological information processing in clinical practice.