Especially the behavioral variant of Frontotemporal Dementia (FTD) may present with impulsivity, social disinhibition or depressive symptoms and these symptoms may create a clinical profile very similar to Bipolar Disorder (BD). In clinical practice, this similarity at symptom level creates substantial diagnostic confusion and often errors. As the treatment approach to the two disorders differ significantly, it is essential to make a reliable differential diagnosis.

In this study we aimed to identify EEG differences between FTD and BD.

For this aim we recruited 22 patients with FTD and 32 patients with BD. Patients in both groups were evaluated with a standardized neuropsychological battery and structural MRI. All patients were evaluated with resting EEG. There were no significant age and gender differences between groups.

EEG power analysis showed that FTD group had increased frontal and temporal theta as compared to the BD group. There were no consistent group differences for other bands.

Based on this result we conclude that quantitative EEG may help differentiating BD from FTD and may eliminate diagnostic uncertainty.