Brain complexity increases in mania.

An important challenge in measuring whole brain activation is to develop a measure that could distinguish between normal and abnormal mood states. The application of chaos theory and non-linear dynamics to problems in biological sciences has resulted in a growing body of advancements and the notion of brain as a complex, non-linear system has attracted physicists, mathematicians, biologists and psychologists alike. To search for a correlation between alterations in chaotic brain states and mood disorders, we compared the fractal dimension of the electroencephalographic (EEG) signal in patients going through a manic episode of bipolar mood disorder (BMD) type I to a control group of healthy adults and showed that the EEG fractal dimension is significantly augmented in our patients. Thus, for the first time, we draw a clear objective distinction between normal and abnormal mood and associated brain states.