Brain immune privilege for many years overshadowed investigation of interaction between the nervous and immune systems. Over time, however, evidence of their interdependence has emerged. In the 1970s, as antibody-mediated autoimmunity was being defined, the neurological disorder myasthenia gravis was shown to be due to autoantibodies that could be passively transferred to mice and removed from humans by plasma exchange. In the 1980s, Fink and Weihe showed that neurons innervate lymph nodes, and from the 1990s onwards, Rothwell and colleagues observed the impact of soluble inflammatory mediators on behaviour. For example, in a key experiment, her team showed that systemic and intraventricular injection of IL-1 led to fever and reduced food motivation in experimental animals, interpreted as “sickness behaviour”; this technique is now used as a model for inflammation-driven depression. Furthermore, IFN- α was unexpectedly found to cause depression when given as a treatment for hepatitis C. More recently, diseases have been identified in which autoantibodies interfere with neuronal function and cause severe psychiatric symptoms, such as N-Methyl D-Aspartate Receptor (NMDAR)-antibody encephalitis. There is now emerging interest in the patho-aetiological role of the immune system in various severe mental illnesses, and the use of immunotherapies in their treatment.

An association of some sort between epilepsy and spirituality, both divine and demonic, has been postulated for millennia (reviewed in Devinsky and Lai 2008). No doubt, this is because people with epilepsy seem to become ‘possessed’ during their seizures, both in the convulsions of the generalised epilepsies and in the strange altered awareness of temporal lobe seizures. In addition, has been the observation that people with epilepsy may show an unusual interest in religion, recently documented in an ancient Babylonian text (Reynolds and Kinnier Wilson 2008). Some date the birth of rational medicine to Hippocrates’ denial that those with the ‘sacred disease’, epilepsy, had mystical power (Todman 2008).

Neurology is the branch of medicine that deals with disorders of the nervous system. The subject started, in its modern form, with the work of Thomas Willis in seventeenth-century England, as mentioned by Joanna Collicutt in Chapter 2. Willis studied the effects of diseases (for instance stroke) of the brain in people in life, and compared these with their anatomical effects at post-mortem. From these observations, he systematically assembled an account of the hierarchical nature of the nervous system from the peripheral nerves to the spinal cord, and then on through an ascending series of structures in the brain. This clinico-pathological tradition reached its apogee in the work of Jean-Martin Charcot in late nineteenth-century Paris (Clifford Rose 1999). Since then, the imaging and laboratory sciences have increasingly informed our understanding of the normal function of the brain and its diseases.