Functionality of Illness Behaviours and Delusions

Medically unexplained symptoms are very common in the general population and result in a huge amount of health care utilisation. In this essay I shall first describe the hypochondriacal and somatoform illnesses, before moving on to a general discussion of illness behaviour. This shall cover various aspects and functions of illness behaviour and some consideration of the delusional forms. Then I say move on to considering illness behaviour as an evolutionary adaptive process, what triggers it and what it triggers in return.

As I was writing this book, I originally intended to focus on delusions. But as progress continued, I found myself focusing more and more on Illness Behaviour. Because of this I have separated the essay in several volumes. This particular volume shall describe illness behaviour and its possible evolutionary role. The later essays shall look at delusional forms of illness behaviour as currently conceptualised. I shall also include a discussion on other delusions that affect the somatic field, purely from the fact that it seemed to go neatly together, rather than because of a desire to reclassify these diagnoses.

I hope that by looking at illness behaviour from an evolutionary point of view, its presence would be understood, as it has a function or several functions. Later I shall make speculative suggestions about the presence of delusions in a field that is currently defined by the absence of delusions. Toward the end of the book, you will find a diagram showing possible connections between illness behaviour and other related factors.