A complex network perspective on brain disease

If brain anatomy and dynamics have a complex network structure as it has become standard to posit, it is reasonable to assume that such a structure should play a key role not only in brain function but also in brain dysfunction. However, exactly how network structure is implicated in brain damage and whether at least some pathologies can be thought of as ‘network diseases’ is not yet clear. Here we discuss ways in which a complex network representation can help in characterising brain pathology, but also in assessing subjects’ vulnerability to and likelihood of recovery from disease. We show how the way disease is defined is related to the way function is defined and this, in turn, determines which network property may be functionally relevant to brain disease. Thus, addressing brain disease ‘networkness’ may shed light not only on brain pathology, with potential clinical implications, but also on functional brain activity, and what is functional in it.