Differences in response criterion and sensory sensitivity to visual flicker among major depressive patients, dysthymic patients, and normal controls were investigated. Also, signal detection confidence ratings and response times were compared. The results indicated that major depressive patients responded more conservatively (i.e. were less willing to respond ‘flicker’) than either of the other groups. The groups did not differ significantly on a criterion free measure of flicker sensitivity. The major conclusions are: (1) previously reported visual flicker differences between depressed patients and normal controls were probably due to the more conservative response criterion of the patients and not to flicker sensitivity differences between groups; and (2) confidence ratings and response times yield similar conclusions with respect to visual flicker sensitivity and response criterion. Therefore, interpretations concerning a sensory or perceptual deficit in depression must take into account the differences in response criterion between depressed patients and normal controls.

In only a few cases is transmissible dementia known to have been acquired by infection from a source outside the individual; the remaining cases can be classified as sporadic, loosely familial, or autosomal dominant. Each group has a characteristic mean age of onset. A range of neurodegenerative diseases (including Alzheimer-type dementia and amyotrophic lateral sclerosis) can also be classified in this way, with similar characteristic mean ages of onset. The emergence of these diseases in later middle age, and the interdependence of age of onset and the type of familial occurrence suggest that these pathological processes are related to those genetic mechanisms which determine senescence. It is argued that the majority of cases of transmissible dementia arise, not from infection, but from the expression of endogenous virogene sequences as part of the aging processes.

The present investigation demonstrates relatively high antibody titres against an E. coli O-antigen in sera from somatically healthy male schizophrenic patients. This observation supports the suggestion that abnormal portasystemic collaterals are relevant to the manifestation of schizophrenia.

Synopsis The CAGE questionnaire was used to screen for at risk drinking among attenders to an inner London health centre. The CAGE functioned most effectively at a cut-off point of two or more affirmative replies, with a sensitivity of 84%, a specificity of 95% and a positive predictive value of 45%. The usefulness of this instrument for screening in general practice is discussed.

Thirty patients who fulfilled DSM–III criteria for schizophrenia but who were within 2 years of presentation were compared with 26 age–matched normal volunteers with respect to CT scan appearances. In the index group the ventricle–brain ratio (VBR) was significantly greater. The VBR values were positively correlated with average alcohol intake and with early physical trauma, and negatively correlated with a family history of schizophrenia. The implications of these findings are discussed in the context of the present uncertainty about the meaning of CT scan findings in schizophrenia.