Individual life experience

Adverse experiences in childhood, such as losing one's mother or father, or being sexually abused, would be expected to increase the risk of psychiatric disorder in adult life, and most research studies tend to confirm this long-term association. There is also evidence for a short-term effect whereby psychosocial stress in adult life can precipitate psychiatric illness in predisposed people. This effect applies both for individual life events of a common kind, such as family bereavement or divorce, and for extraordinary disasters (see Chapter 6 on PTSD). Chronic social stresses, such as marital difficulties or bad housing, can also contribute. In contrast, supportive social networks, and close confiding relationships with others, provide some protection against psychiatric disorder following adverse life events.

Life event experience may be measured by the following:

• official records in the case of certain major events like widowhood or divorce

• questionnaires, which are relatively easy to score but involve oversimplification

• standardized interviews, such as the Life Events and Difficulties Schedule (LEDS) developed by Brown and Harris.

The effects of life experiences can be satisfactorily investigated only by prospective follow-up of people subjected to adversity, but such studies take many years to complete and are expensive. Many published studies have therefore


used retrospective methods, and their interpretation is subject to error for the following reasons:

• Mistaking the direction of causality. An event apparently precipitating an illness (such as losing a job) may really be the result of changes in the patient's behaviour during the prodromal phase of that illness.

• Effort after meaning. Some patients unwittingly exaggerate their experience of life event stress in order to explain the illness. For example, a woman who has given birth to a baby with a congenital abnormality will be more likely than a control to report adverse events during pregnancy.

• Inaccurate recollection of timing of life events in relation to illness onset.

• Recall bias. For example, depressed persons naturally tend to recall negative memories in preference to positive ones; this means they are intrinsically more likely to recall adverse life events than control subjects.

Kindling refers to a presumed process whereby repeated applications of a stimulus produce an escalating response. This theory has been used to try to understand the course, for example, of recurrent unipolar depression, in which the time between episodes tends to decrease, and the role of life events in provoking an episode becomes less prominent (see Chapter 5).

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