The role of life events in depressive illness: is there a substantial causal relation?

Assessment of the relationship of life events to minor and major affective illness is beset by several methodological problems. The reliability and validity of measures is not entirely satisfactory. When the stress concept used is that of 'threat' or 'emotional distress' it becomes of crucial importance to define clearly the criterion variable: in particular, it is necessary to distinguish normal distress responses from depressive illness. In those studies using general practice or hospital patients it is important to determine whether life events provoke depressive illness or some illness behaviour such as service utilization. Because of these problems it is still not certain that life events cause depressive illness.