T he role of independent life events in schizophrenic relapses has been well documented in both retrospective (1, 2) and prospective (3, 4) studies. However, what deserves further consideration is that at least 50% of the instances of schizophrenic relapse occur without any increase in major life events in the preceding 1-month period (4, 5), suggesting that these patients may experience acute accentuations of vulnerability to relapse as a result of natural oscillation in their biological systems (4). To our knowledge, to date there have been no investigations relating the cognitive characteristics of schizophrenic subjects to the level of stress at the time of relapse, and the aim of the present study was to start to fill this gap.Schizophrenic vulnerability (comprising, for example, certain cognitive dysfunctions and specific coping limitations) may be associated with sensitivity to socioenvironmental stress factors that lift the individual's susceptibility over the threshold beyond which an exacerbation of psychotic symptoms or a relapse can be expected (6, 7).One serious difficulty in carrying out this kind of study relates to the process of assessing and determining the degree of reliability of the recollection of life events during the course of the disease. To avoid the common biases that can occur in this kind of research, a series of measures were adopted: prospective research with follow-up analysis, schizophrenic subtyping (in order to avoid producing results that cannot be extended to an entire schizophrenic subpopulation), the use of appropriate criteria to define relapse, and the use of appropriate instruments for the assessment of stressful life events, such as Brown and Harris's Life Events and Difficulty Schedule (8), which was conducted by a trained expert.In their ongoing longitudinal study of developmental processes in schizophrenia, Nuechterlein et al. (5,9) focused on several information-processing neuropsychological and neurophysiological indexes ("stable vulnerability indicators"), but they did not consider each subject's coping strategies and the level of subjective experiences, nor did they consider the P300 event-related potential, which is one of the most reliable indexes of information-processing dysfunction (10-12).Moreover, lower rates of relapse (13,14) have been associated with a small P300 amplitude in schizophrenic patients.We may hypothesize that this susceptibility to stress