Lesson 1: Predisposition, Biological Factors, and the Brain

Introduction

In the lesson content you will come across some terms in maroon color that are bolded. Look them up in the course Glossary.

Terminology

For a person to go to bed one night as “normal” and then wake up the next morning with some form of mental illness would be unusual. Mental illness rarely resembles a light switch – normal one minute, then, with a flick of the switch, abnormal the next. To some degree everyone has vulnerabilities with respect to behaviour. Whether these vulnerabilities affect our behaviour in a negative way depends on the nature, number, and degree of the vulnerabilities we have, combined with the stressors we face in our lives.

In psychology, the term predisposition is often used when discussing abnormal behaviour. Predisposition is the tendency of a person with vulnerabilities to develop a psychological disorder given the appropriate environmental circumstances. These circumstances, or stressors, need not be the same for each person. Vulnerabilities also vary widely. For example, one can have biological or genetic vulnerabilities, experiential vulnerabilities (traumatic events in childhood), or skill deficit vulnerabilities (poor or non-existent coping mechanisms).

In addition to predisposition and vulnerability, the concepts of primary cause and precipitating cause are important when discussing reasons for abnormal behaviour. Although not always obvious to an observer, all mental illnesses have primary causes. For a person with hoplophobia (a fear of guns), the primary cause could be that he or she witnessed a gun-related murder as a child. Precipitating causes are like a collection of children’s building blocks being stacked one upon the other until a point at which, if even the smallest block is added, the entire pile falls to the ground. In this example, the last block is the precipitating cause of the fall of the structure. When comparing building blocks with human stressors, the size and number of total blocks before the collapse differs for each person.