Have you ever wondered about the workings of your brain? If so, an EEG electroencephalogram (EEG) can help you find out!
What is EEG? An EEG is a measure of the electrical activity in your brain. It is a painless procedure that uses electrodes placed on the surface of the scalp to detect the underlying brain waves. This information is recorded and compared with normative databases to identify possible irregular patterns of brain activity. Although EEG is not classified as a diagnostic tool itself, the information it provides can be used to assist the assessment and diagnostic process. This could be helpful among children, who struggle to articulate or where the presentation is complex and there is extensive comorbidity and overlapping symptomatology. The EEG can provide information that helps guide treatment, its efficacy and the likely prognosis.
There are various brain waves present and each has a different frequency (slow to fast) – Delta, Theta, Alpha, Beta and Gamma. Excess or deficient activity in either of these brainwaves in a particular area of the brain might explain a client’s state of arousal (i.e over, under or unstable), attention problems, sleep difficulties, and mood (i.e depressed, anxious, dissociative, etc.).
The EEG has been examined in a range of disorders such as ADHD, Autism, anxiety and depression. This information should be used together with a comprehensive clinical assessment to make an accurate diagnosis.
ADHD can cause attentional difficulties, impulsivity and hyperactivity in both children and adults and it can negatively impact performance at work or school, impair social and organizational skills and lead to risk-taking behaviour. It often co-exists with other conditions such as anxiety, depression and sleep disorders.
Decades of EEG research into ADHD, have shown high levels of slow activity (i.e Theta) and low levels of fast activity (Beta) around the frontal and parietal areas of the brain (which are important for attention and executive functioning) in ADHD clients as compared to control subjects. This type of brain activity has been shown to be a reliable prognostic factor in ADHD, and a favourable predictor in treatment and medication choices.
Autism is a complex developmental disorder that affects social communication, sensory processing and flexibility of behaviour and emotion. The underlying neurophysiology in Autism is less well understood and early detection can be problematic due to the lack of specific biomarkers. Various EEG studies have shown abnormal connectivity in brain regions at different development stages in children, which might be an explanation for the delayed presentation of symptoms.
A study by Kulisek and colleagues (2008) revealed significantly lower synchronization of brain connectivity in children with Autistic Spectrum Disorder, compared to controls. Additional EEG studies have supported the hypothesis of impaired brain connectivity underpinning the etiology of Autism.
Autistic Spectrum Disorder is known to impair mirror neurons, that are responsible for mimicking and understanding the actions of another person. Hense, Autistic individuals struggle with ‘theory of mind’ – the ability to infer the ‘mind of the other’ and can be very literal in their interpretations.
Bosl and colleagues (2011) conducted research indicating very different EEG complexities in infants from families with a history of ASD. This research could assist in identifying ‘at risk’ individuals for developing Autistic Spectrum Disorder.
Depression and Anxiety
Depression and Anxiety affect approximately 3 million Australians per year. There are different presentations of depression and anxiety that have varied patterns of arousal in the brain.
For example, low activity in the frontal cortex has been linked to depression and anxiety.
Additionally, EEG studies have found a significant link between hemispheric asymmetry in the frontal regions of the cortex and depressive symptoms. Finding on EEG have supported the idea of increased positive emotion being associated with greater activity in the “Left” frontal region, and greater activity in the “Right” frontal region being associated with negative and withdrawal emotions. Those who suffer from depression and anxiety have exhibited greater relative right frontal EEG activity. The findings could be useful predictors of likely best treatment practices and prognosis.
Although the EEG is not a gold standard, stand-alone diagnostic tool; it is a useful adjunct to testing a diagnostic hypothesis, evaluating prognosis and treatment responses. The EEG is painless, non-invasive, easy to complete and relatively inexpensive and therefore, where appropriate, a valuable service offering.