David J. LaPorte

Subanesthetic Doses of Ketamine Stimulate Psychosis in Schizophrenia

We administered ketamine to schizophrenic individuals in a double-blind, placebo-controlled design using a range of subanesthetic doses (0.1, 0.3, and 0.5 mg/kg) to evaluate the nature, dose characteristics, time course, and neuroleptic modulation of N-methyl-D-aspartate (NMDA) antagonist action on mental status in schizophrenia. Ketamine induced a dose-related, short (< 30 minutes) worsening in mental status in the haloperidol-treated condition, reflected by a significant increase in BPRS total score for the 0.3 mg/kg (p =. 005) and 0.5 mg/kg (p =. 01) challenges. Positive symptoms (hallucinations, delusions, thought disorder), not negative symptoms accounted for these changes. These ketamine-induced psychotic symptoms were strikingly reminiscent of the subjects symptoms during active episodes of their illness. Results from six patients who were retested in the same design after being neuroleptic-free for 4 weeks failed to indicate that haloperidol blocks ketamine-induced psychosis. Several subjects evidenced delayed or prolonged (8–24 hours) psychotomimetic effects such as worsening of psychosis with visual hallucinations. These data suggest that antagonism of NMDA-sensitive glutamatergic transmission in brain exacerbates symptoms of schizophrenia.

Racial differences in body type preferences of men for women.

OBJECTIVE Research indicates that African-American women have a significantly higher prevalence of obesity, a markedly lower prevalence of eating disorders, and greater satisfaction with their bodies than Euro-American women. One potential contributing explanation for this difference may be differential body type preferences between the men in the two communities. METHOD Sixty-three African-American and 116 Euro-American men were asked to rank, in order of attractiveness, a series of silhouettes of women of varying sizes. Additionally, they answered questions concerning their current relationships. RESULTS Euro-Americans chose significantly thinner figures, and reported wishing their girlfriends would lose weight significantly more often than African-Americans. DISCUSSION These differential preferences may translate into greater pressure within the Euro-American community for women to be thin than in the African-American community; however, a small effect size suggests that factors other than race contribute to mens body type preferences.

Impact of exposure to pro-eating disorder websites on eating behaviour in college women.

OBJECTIVE To assess whether exposure to pro-eating disorder (pro-ED) websites influences college womens eating behaviours. METHOD Female college students with a body mass index (BMI) higher than 18 and no history of an ED were exposed to either pro-ED websites, healthy/exercise websites or tourist websites for 1.5 hours and were given quantitative and qualitative measures designed to assess changes in eating behaviour. RESULTS The pro-ED website group experienced a significant one-week decrease in caloric intake from pre- to post-exposure (12,167 calories vs. 9697 calories). Following exposure, participants reported using techniques on the websites to aid with food reduction and had strong emotional reactions to the websites. These changes persisted for 3 weeks following the studys end. DISCUSSION Even modest exposure to pro-ED websites may encourage significant changes in caloric intake and increased disordered eating behaviours. By extension, even greater exposures to these websites by at-risk females may contribute to the development of EDs.

Treatment response in obese binge eaters: preliminary results using a very low calorie diet (VLCD) and behavior therapy

The present study compared the treatment response of male and female obese binge eaters and nonbinge eaters attending a university-based weight reduction program employing a very low calorie diet (VLCD) and concurrent behavior therapy. Twenty-nine percent of female patients (n = 19) and 22% of male patients (n = 6) were characterized as binge eaters based on their scores on the Binge Eating Scale. No significant differences were found between binge and nonbinge groups on measures of weight loss, adherence to the diet, or drop-out rate, although a trend towards greater attrition in the binge group (32%) relative to the nonbinge group (17%) was noted. However, binge eaters had significantly higher pretreatment levels of trait anxiety, state anxiety, and depression as well as higher within treatment levels of anxiety and depression despite significant reductions in depression over the course of treatment. Further examination revealed a binge status X sex interaction effect on state anxiety. Binge-eating females had significantly higher anxiety levels pretreatment and throughout the 10 weeks of the study. No differences between binge and nonbinge males on levels of anxiety were found. These preliminary results tentatively suggest that a VLCD in conjunction with behavior therapy may be an effective method of weight loss for this segment of the obese population, but that elevated levels of anxiety persist in female patients. Future studies must address the long-term maintenance of weight loss in this population as well as other treatment strategies.

Absence of ketamine effects on memory and other cognitive functions in schizophrenic patients

Glutamatergic dysfunction may play an important role in both the pathophysiology of schizophrenia, and impaired memory commonly observed in that disorder. NMDA receptor antagonists impair learning/memory in animal models, putatively based on its ability to block long-term potentiation (LTP) in the hippocampus. Although well studied in animal models, research in humans is limited and confounded by administration of NMDA antagonists before the learning experience. Based on presumed glutamatergic dysfunction, it was predicted that the NMDA antagonist ketamine would not effect memory in schizophrenic subjects. Bolus injections of ketamine (0.5 mg/kg) or placebo were given to seven patients with schizophrenia in this double-blind cross-over study. Immediately prior to injection, subjects were administered verbal and figural memory tests. Delayed recalls were obtained 30-45 min postinjection. In order to rule out drug-induced generalized cognitive impairments, other cognitive tasks were administered pre- and postinjection. The results indicate no differences between the drug and placebo conditions for either memory task, and no changes on the other cognitive tasks observed.

Child sexual abuse and bulimic symptomatology: relevance of specific abuse variables

OBJECTIVE This study examined specific aspects of child sexual abuse in relation to symptom severity among hospitalized patients diagnosed with bulimia nervosa. METHOD Participants were 45 hospitalized bulimic women who reported a history of child sexual abuse. Structured interviews were conducted in order to obtain detailed information regarding specific features of the abusive event(s). Participants also completed instruments that measured depression and eating pathology. RESULTS There were no significant differences in severity of depression or eating disturbance among women reporting differing abusive experiences including intrafamilial versus extrafamilial abuse, abuse with or without the use of physical force, one versus multiple incidents, early abuse versus abuse occurring after age 14, contact versus noncontact abuse, disclosed versus undisclosed, and combined physical/sexual abuse versus sexual abuse alone. CONCLUSION The specific characteristics of child sexual abuse are not related to the level of symptomatology for hospitalized bulimic patients. This study suggests that differences in the nature of the abuse may not be as important as the fact that the abuse occurred in the first place.

Gender differences in perceptions and consequences of an eating binge

Little systematic research has examined the factors that contribute to perceptions of an eating binge. This study showed videotapes of a single male, single female, or three females eating a variable number of doughnuts at different rates to male and female undergraduate subjects. Subjects were asked to label their own eating as a binge or not, had they eaten like the person on the videotape, and how they would feel afterward. The majority of female subject labeled their own eating as a binge under all conditions, and endorsed negative emotional outcomes. Males required a large number of doughnuts, or rapid consumption before the majority labeled it a binge, and experienced mostly gastrointestinal outcomes. Many noneating disordered women in our culture may be labeling much of their eating as a binge and experience dysphoria afterward.

Covert visual attention in schizophrenia spectrum personality disordered subjects: Visuospatial cuing and alerting effects

A recent study observed lateralized deficit in the disengagement of covert visual attention in schizophrenic patients. Subsequent attempts to replicate this finding have had mixed results. Differences in the neuroleptic treatment or other secondary factors associated with schizophrenia are some of the possible reasons for these inconsistent findings. In this study, we examined the ability to shift covert visual attention in neuroleptic-naive, schizophrenia spectrum personality disordered (SSPD; n = 35) subjects and normal controls (n = 34) under a variety of spatial cuing and alerting conditions. We hypothesized that SSPD subjects would have difficulty with disengagement of covert visual attention from an invalidly cued left visual field when the target appeared in the right visual field in comparison to the normal subjects. As predicted, schizophrenia spectrum personality disordered subjects had significantly longer latencies for the right visual field invalid targets than normals (p = .014). Under the remaining cue conditions, spectrum subjects performed normally. Consequently, the cost of left visual field invalid cueing for the right visual field target was significantly higher in spectrum personality subjects than in normals. The cost for the invalid right visual field cue and the benefits of valid cue in both fields were very similar in the two groups. The findings of an asymmetrical deficit in the disengagement and shift of covert visual attention in schizophrenia spectrum subjects are similar to the ones observed in patients with unilateral left hemisphere lesions.

Psychosis-proneness and verbal memory in a college student population

Previous research has revealed numerous neuropsychological deficits in schizophrenics. Research on individuals with schizotypal personality features has also demonstrated similar neuropsychological deficits. However, the latter literature is limited in scope. This study examined verbal memory function in psychometrically identified (Chapman Scales) psychosis-prone college students (n = 409). Subjects were administered a standard verbal memory procedure (Logical Memory; Wechsler Memory Scale-Revised) as well as measures of verbal intelligence (Shipley Scale) and depression (Beck Depression Inventory). Results reveal no relationship between degree of schizotypic features and recall measures (immediate recall, delayed recall, and retention rate). Moreover, comparisons between low schizotypic subjects and those scoring at the extreme (greater than 2 standard deviations above the mean) also failed to reveal significant differences in recall. These results raise the possibility that memory deficits may be specific to schizophrenia and not the schizophrenia spectrum or that they are restricted to only those with the familial form of the disorder (i.e., those with family histories of schizophrenia).

Influences of Gender, Amount of Food, and Speed of Eating on External Raters' Perceptions of Binge Eating

Traditional methods for examining binge-eating (e.g. food diaries, laboratory binges), primarily employing clinical samples, have a number of limitations. This paper details three studies utilizing a new methodology to examine perceptions of binge eating: standard videotapes of male and female models consuming doughnuts. College students (n = 459) viewed one of nine videotapes and were asked if the eating behavior of the model was a binge or not. Variables manipulated include gender of the model, number of doughnuts, rate of eating and social (vs. solitary) eating. The number of doughnuts eaten by a female model was sufficient for female subjects to label it as a binge. In order for a male to have binged, females responded to the amount; males required both speed and amount. Results are discussed in terms of their relevance for understanding perception of binge eating in normal and clinical populations.