Memory functioning and negative symptoms as differential predictors of social problem solving skills in schizophrenia.

BACKGROUND: Neurocognition in general, and memory functioning in particular, as well as symptoms have all been shown to be related to social problem solving (SPS) in schizophrenia. However, few studies have directly compared the relative contribution of neurocognition vs. psychiatric symptoms to the components of SPS. METHOD: Sixty outpatients (aged 21-65) who met DSM-IV criteria for schizophrenia or schizoaffective disorder were administered a broad battery of memory tests and assessed for severity of positive and negative symptoms as part of a baseline assessment of a study of psychiatric rehabilitation. Multiple regression analyses were used to examine the contribution of memory functioning vs. symptoms on receiving, processing, and sending skill areas of social problem solving ability. RESULTS: An index of verbal learning was the strongest predictor of processing skills whereas negative symptoms were the strongest predictor of sending skills. Positive symptoms were not related to any of the three skill areas of social problem solving. CONCLUSIONS: Memory functioning and psychiatric symptoms differentially predict selected areas of social problem solving ability in persons with schizophrenia. Consistent with other reports, positive symptoms were not related to social problem solving. Consideration of both neurocognition and negative symptoms may be important to the development of rehabilitation interventions in this area of functioning.

Common factors across acute subjective effects of nicotine.

Nicotine intake acutely induces many different subjective mood effects, which may be critical to understanding nicotine reinforcement. Some of these effects may cluster together, perhaps reflecting common underlying mechanisms (e.g., catecholamine release). In this study of 93 smokers, ex-smokers, and nonsmokers, we conducted factor analyses of responses to a battery of subjective measures (23 visual-analog scale items and Profile of Mood States [POMS] scales) following acute nicotine nasal spray administration. The goal was to identify homogeneous clusters among these diverse effects of nicotine. A subject's response to nicotine on each measure was determined by the slope of his or her dose-response curve (0, 10, 20 microg/kg nicotine). Results of factor analyses identified five factors, labeled "head rush" (head rush, buzzed, lightheaded, jittery), "positive affect" (comfortable, satisfied, relaxed, etc.), "negative affect" (anger, depression, tension), "fatigued" (tired, sedated, fatigue), and "energized" (stimulated, vigor). The factor structure was consistent between smoking status groups. However, as expected, groups differed on mean factor scores for head rush, positive affect, and energized, perhaps reflecting tolerance to these effects of nicotine. Although these specific findings require replication, they suggest that acute subjective responses to nicotine can be captured by a few common factors, potentially simplifying this assessment. Similar research may provide directions for exploring potential mechanisms responsible for these broad subjective effects of nicotine.

The consistency of acute responses to nicotine in humans.

Nicotine has many acute subjective, physiological, and behavioral effects in humans, some of which may explain why nicotine produces dependence. Individual differences in the magnitude of these effects (i.e., nicotine sensitivity) are of interest to many researchers, such as those examining vulnerability to dependence and processes related to chronic tolerance. However, such characterization of individual differences depends on the consistency of the observed responses, and the consistency of acute effects of nicotine in humans has not been studied systematically. We examined the consistency of the acute effects of the same dose of nicotine administered by nasal spray across multiple drug administration trials, within as well as between sessions. Subjective (i.e., self-reported effects), cardiovascular, and performance measures were assessed following each of four dosing trials of nicotine (20 microg/kg) on three sessions and of placebo on one session. For those measures in which the main effect of nicotine vs. placebo was significant, intraclass correlations were calculated for different sets of trials across different numbers of sessions. Our objective was to determine whether the consistency of responses declined when those responses were based on smaller numbers of trials or sessions, in an effort to guide future research in this area. Results indicated that the consistency of nicotine effects is generally high, even across trials within just one session. Additional research is needed to determine the generalizability of these findings to other methods of nicotine administration, including smoking, and to clarify the extent to which this consistency reflects characteristic consistency of the pharmacological actions of nicotine per se vs. consistency of nonspecific responses to the drug administration procedure.