Placebo analgesia was produced by conditioning trials wherein heat induced experimental pain was surreptitiously reduced in order to test psychological factors of expectancy and desire for pain reduction as possible mediators of placebo analgesia. The magnitudes of placebo effects were assessed after these conditioning trials and during trials wherein stimulus intensities were reestablished to original baseline levels. In addition, analyses were made of the influence of these psychological factors on concurrently assessed pain and remembered pain intensities. Statistically reliable placebo effects on sensory and affective measures of pain were graded according to the extent of surreptitious lowering of stimulus strength during the manipulation trials, consistent with conditioning. However, all of these effects were strongly associated with expectancy but not desire for relief. These results show that although conditioning may be sufficient for placebo analgesia, it is likely to be mediated by expectancy. The results further demonstrated that placebo effects based on remembered pain were 3 to 4 times greater than those based on concurrently assessed placebo effects, primarily because baseline pain was remembered as being much more intense than it actually was. However, similar to concurrent placebo effects, remembered placebo effects were strongly associated with expected pain levels that occurred just after conditioning. Taken together, these results suggest that magnitudes of placebo effect are dependent on multiple factors, including conditioning, expectancy, and whether analgesia is assessed concurrently or retrospectively.

This article reports an analysis of the efficacy data submitted to the U.S. Food and Drug Administration for approval of the 6 most widely prescribed antidepressants approved between 1987 and 1999. Approximately 80% of the response to medication was duplicated in placebo control groups, and the mean difference between drug and placebo was approximately 2 points on the 17-item (50-point) and 21-item (62-point) Hamilton Depression Scale. Improvement at the highest doses of medication was not different from improvement at the lowest doses. The proportion of the drug response duplicated by placebo was significantly greater with observed cases (OC) data than with last observation carried forward (LOCF) data. If drug and placebo effects are additive, the pharmacological effects of antidepressants are clinically negligible. If they are not additive, alternative experimental designs are needed for the evaluation of antidepressants.

Objective Cognitive deficits are prominent in schizophrenia. Patients have an average score one standard deviation below normal on a broad spectrum of cognitive tests. It has been repeatedly noted, however, that 20%–25% of patients differ from this general pattern and score close to normal on neuropsychological testing. This study used brain morphometry to 1) identify brain abnormalities associated with more severe cognitive deficits and 2) help determine whether cognitively relatively intact patients perform better because they have less severe illness or because they have a different illness. Method Patients were assigned to a neuropsychologically near normal (N=21) subgroup if they scored within 0.5 standard deviation of healthy comparison subjects (N=30) on four tests of attention and verbal and nonverbal working memory, and to a neuropsychologically impaired (N= 54) group if they scored at least 1.0 standard deviation below that of comparison subjects. Subgroup assignments were confirmed with the California Verbal Learning Test and degraded-stimulus Continuous Performance Test. Volumes of ventricular compartments, hippocampus, amygdala, thalamus, cerebellum, and regional cortical gray and white matter were dependent variables. Differences among groups were evaluated by using linear mixed-model multivariate analyses with gender, age, and height as covariates. Results Both neuropsychologically near normal and neuropsychologically impaired patients had markedly smaller gray matter and larger third ventricle volumes than healthy comparison subjects. Only neuropsychologically impaired patients, however, had significantly smaller white matter and larger lateral ventricle volumes than healthy comparison subjects. Conclusions Although both neuropsychologically impaired and neuropsycho-logically near normal patients have marked neuropathology in their gray matter, the relative absence of white matter pathology in the neuropsychologically near normal group suggests the possibility of differences in the disease process.

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