Brain electrical activity mapping for diagnosing psychiatric disorders

The etiology of diseases affecting the brain has been linked to various neurotransmitters such as acetylcholine, dopamine, gama aminobutyric acid (GABA) and serotonin. For instance, Alzheimer's disease (AD) is reported to have strong links with impairment in acetylcholine, serotonin and GABA systems in certain regions of the brain, while psychoses including schizophrenia are associated with aberant levels and activities of dopamine and serotonin. In the absence of specific and reliable markers or a commonly accepted gold standard, diagnosis of neuropsychiatric diseases in living patients is probabilistic and based on clinical diagnostic criteria. Traditionally, the diagnosis of dementia including Alzheimer's disease has been done through neurological assessment that combines scores from validated instruments like the mini-mental state examination (MMSE) tool and clinical neurology expertise. Diagnosis of psychoses is based on criteria from either the Diagnostic and Statistical Manual (DSM) of mental disorders which is used more commonly in North America, or the International Classification of Diseases (ICD) which is used more commonly in Europe and other parts of the world. Quantitative EEG (qEEG) involves computer-assisted imaging and statistical analysis of the EEG for detecting abnormalities, assisting the physician in making a diagnosis, and other purposes relating to patient care. In addition, qEEG is relatively inexpensive, and without using ionizing radiation it is able to noninvasively produce images of both excitatory and inhibitory cortical neuronal activity rather than secondary hemodynamic processes, and the spectra can be displayed as statistical probability maps in which brain areas can be made to "light up" in proportion to the abnormality of their activity. These maps form vivid illustrations of the clinical point that a brain problem underlies a patient's symptoms. It is unclear whether the diagnosis of a neuropsychiatric disorders based on standard traditional criteria is in agreement with resul