Assessment of Effective Connectivity in Alzheimer’s Disease Using Granger Causality

Alzheimer’s disease (AD) is a neurological disorder accompanied by cognitive impairment. A complete understanding of the neurological processes involved in AD is a leading challenge in brain research. In this study, resting-state magnetoencephalography (MEG) activity from 36 AD patients and 26 healthy controls was evaluated by means of Granger Causality (GC), an effective connectivity measure that provides an estimation of the information flow between brain regions. Our results showed widespread increments in connectivity in delta (δ, 1–4 Hz) band. On the other hand, decrements in connectivity patterns were found for theta (θ, 4–8 Hz), beta (β, 13–30 Hz), and gamma (γ, 30–65 Hz) bands. These findings strength the disconnection hypothesis in AD, and reveal GC as a useful parameter for AD characterization.