We will propose a critical review of the scientific literature regarding pain and schizophrenia, examine the empirical basis for the reported pain insensitivity of schizophrenia, and emphasize the distinction between behavioral responses to pain or self-reported pain and physiological response to painful stimuli. Litterature is scarse and could be classified in 4 groups: case reports (n = 9), clinical studies (n = 23), experimental research (n = 20) and review articles (n = 5).

The analysis of Case reports and clinical studies show reduced pain reactivity in patients with schizophrenia compared to healthy controls or other psychiatric patients. In the same vein, experimental studies using self-report measures of pain reactivity generally reported higher pain perception thresholds in patients with schizophrenia. However, the only experimental study using a neurophysiological measure of pain reactivity (the nociceptive RIII reflex) demonstrated a normal pain threshold in schizophrenia.

Review of clinical and experimental data indicates that in most situations behavioral pain reactivity and self-reported responses to pain are reduced in schizophrenia. However, there is little or no physiological evidence supporting pain insensitivity in schizophrenia. It can be suggested that the widely accepted notion of reduced pain sensitivity in schizophrenia is related more to a different mode of pain expression than to a real endogenous analgesia. We will also present preliminary data on pain sensitivity associating behavioural pain reactivity measurements, "objective" electrophysiological assessments and neurovegetative function recordings. Our results are in the line of the literature and strongly suggest that there is no analgesia in schizophrenia but a different mode of pain expression.