qEEG data gathering is the procedure whereby electrical activity on the cerebral cortex, specifically the frequency bandwidths that make up the raw EEG, are collected from different sites across the scalp. The scalp locations of where the data is collected are determined by the International 10-20 System and can be between 2 and 19 electrodes. When more locations are used, specific activity can be more reliably associated with a specific area of the brain. The individual’s brain wave patterns are compared on a database using a normative population where topographical brain maps are produced.
The purpose of the normative database software is to compare a patient’s qEEG with other members of a sample population (Demos, 2005). Normative databases has been established for a wide age range, specifically 6 to 95 years. qEEGs use a well developed database to examine the specific brain wave patterns to help identify patterns that may be associated with particular psychiatric disorders (Butnik, 2005). This demonstrates that qEEGs have an important role in influencing a psychiatric diagnosis and possible management options (Cantor & Chabot, 2009). qEEGs have shown that systematic changes occur in our brain wave frequencies with maturation. Furthermore, studies have shown that changes in qEEG functioning is not culturally or ethically dependent (Cantor & Chabot, 2009).
QEEG and the ADHD Brain
There is a large body of research that examines evidence of qEEG patterns and individuals with Attention Deficit Hyperactivity Disorder. Fonseca et al. (2008) discovered that in a group of 30 children with ADHD, compared to a control group, ADHD children showed increased slow wave theta levels and an increase in delta activity. However, no particular brain regions were discussed in this study and the qEEG was taken across 15 locations as opposed to 19, therefore lowering the accuracy of locating the specific brain activity to specific regions. In the study both eyes open and eyes closed were recorded.
In an eyes closed qEEG study of ADHD children, increased levels of slow wave theta were found which is consistent with other studies but excessive alpha levels were also found. These abnormalities were present in the frontal and central regions. This pattern was seen across childhood, with elevated frontal theta levels additionally seen in adults (Cantor & Chabot, 2009).
Chabot et al (2005) conducted a meta analysis of qEEG data on children and adolescents with AD/HD. qEEG eyes open studies using 2 or 3 locations, of children with ADHD, were characterised by a deficit of alpha and beta levels in central and parietal brain regions. Since the development of using a larger number of recording locations, resting eyes closed qEEGs of children with ADHD are seen to be characterised by increased delta and theta and decreased alpha, specifically in the occipital region. However, the sample size as well as gender ratio was not discussed nor were the locations that were recorded, making it difficult to validate findings. Concentrating specifically on Attention Deficit Disorder, studies have concluded that qEEGs are characterised by generalised high levels of theta, particularly high in frontal regions, and generalised low levels of beta across the brain (Chabot et al., 2005).
In typical children, the brain activity changes and develops with age; a process known as maturation. In particular, as a child gets older, there is a decrease in theta levels and an increase in beta leves. This suggests that the differences seen in qEEGs between ADHD and normal populations is evidence that ADHD could be due to a developmental delay. Bresnaham and Barry, (2002), conducted research on adults with ADHD which demonstrated that there is a difference in brain activity between an ADHD adult population and control groups, with ADHD adults exhibiting reduced beta levels, but there being a less significant difference compared to children with ADHD. This suggests that the brain activity in normal and ADHD populations do change, however, individuals with ADHD never catch up with their counterparts. This study examining adults with ADHD with qEEGs eyes open in a rest position showed that ADHD adults have elevated theta activity (Bresnaham & Barry, 2002).
