Injury and disease

Head injuries are a major health issue in most countries around the world. In general it would be beneficial to understand the effects of these injuries on the connectivity of brain. One type of head injury that has been shown to affect network function in the brain is traumatic brain injury (TBI). Pandit and colleagues, for example, have shown that the functional brain networks of TBI patients move away from a small-world organisation with an increase characteristic path-length. In their work they suggest that this increase is due to the damage long-range connection suffer from.

One of the diseases that are of particular interest for network theoretical analyses is Alzheimer's disease (AD). By comparing AD patients to a healthy control group, Supekar and colleagues found that the clustering coefficient of AD patients is reduced. Lo and colleagues on the other hand found that AD patients showed an increase in characteristic path-length. Both results agree, however, that the small-world organisation in AD patients is affected as an effect of the disease.

Another interesting area of research is attention deficit hyperactivity disorder (ADHD). In a study of the functional networks of children with ADHD, Wang and colleagues found that the network organisation of these children becomes more lattice like with an increase in local efficiency. Lattice networks are often associated with an increase in disease tolerance, which may therefore be interpreted as a defence mechanism.