Renu Kotwal

Impulsivity across the course of bipolar disorder

OBJECTIVE To determine whether abnormalities of impulse control persist across the course of bipolar disorder, thereby representing potential state markers and endophenotypes. METHODS Impulse control of 108 bipolar I manic or mixed patients was measured on three tasks designed to study response inhibition, ability to delay gratification, and attention; namely, a stop signal task, a delayed reward task, and a continuous performance task, respectively. Barrett Impulsivity Scale (BIS-11) scores were also obtained. Patients were then followed for up to one year and reassessed with the same measures if they developed depression or euthymia. Healthy comparison subjects were also assessed with the same instruments on two occasions to assess measurement stability. RESULTS At baseline, bipolar subjects demonstrated significant deficits on all three tasks as compared to healthy subjects, consistent with more impulsive responding in the bipolar manic/mixed group. In general, performance on the three behavioral tasks normalized upon switching to depression or developing euthymia. In contrast, BIS-11 scores were elevated during mania and remained elevated as bipolar subjects developed depression or achieved euthymia. CONCLUSIONS Bipolar I disorder patients demonstrate deficits on laboratory tests of various aspects of impulsivity when manic, as compared to healthy subjects, that largely normalize with recovery and switching into depression. However, elevated BIS-11 scores persist across phases of illness. These findings suggest that impulsivity has both affective-state dependent and trait components in bipolar disorder.

Characterizing impulsivity in mania

OBJECTIVE To determine whether specific aspects of impulsivity (response disinhibition, inability to delay gratification, inattention) differ between healthy and bipolar manic subjects, and whether these aspects of impulsivity were associated with each other and severity of affective symptoms. METHODS Performance of 70 bipolar I manic or mixed patients was compared to that of 34 healthy subjects on three tasks specifically designed to study response inhibition, ability to delay gratification, and attention; namely, a stop signal task, a delayed reward task, and a continuous performance task, respectively. Correlations among tasks and with symptom ratings were also performed. RESULTS Bipolar subjects demonstrated significant deficits on all three tasks as compared to healthy subjects. Performance on the three tasks was largely independent. Task performance was not significantly associated with the severity of affective symptom ratings. However, measures of response inhibition and attention were sensitive to medication effects. Differences in the delayed reward task were independent of medication effects or symptom ratings. During the delayed reward task, although bipolar patients made their choices more slowly than healthy subjects, they were significantly more likely to choose a smaller, but more quickly obtained reward. Moreover, performance on this task was not associated with performance on the other impulsivity measures. Manic patients showed more impulsive responding than mixed patients. CONCLUSIONS Bipolar I manic patients demonstrate deficits on tests of various aspects of impulsivity as compared to healthy subjects. Some of these differences between groups may be mediated by medication effects. Findings suggested that inability to delay gratification (i.e., delayed reward task) was not simply a result of the speed of decision making or inattention, but rather that it reflected differences between bipolar and healthy subjects in the valuation of reward relative to delay.

Comparison of obese men and women with binge eating disorder seeking weight management

OBJECTIVE: This study examined whether obese males with binge eating disorder (BED) seeking weight loss treatment differed significantly from obese females with BED seeking weight loss treatment in developmental variables, weight loss history, current and lifetime prevalence of psychiatric disorders, and metabolic abnormalities. METHODS: Psychiatric (using the Structural Clinical Interview for DSM-IV), medical, and laboratory assessments of 44 obese males with BED were compared with assessments from 44 age- and race-matched obese females with BED seeking weight loss treatment. RESULTS: High rates of mood disorders, anxiety disorders, and metabolic syndrome were observed in the population as a whole. Obese males with BED had attempted significantly fewer diets, medications and supplements for weight loss before seeking weight loss treatment. The two genders did not differ significantly in any other of the examined variables. CONCLUSIONS: Our results suggest that while obese men and women with BED who present for weight management are very similar, males had fewer previous attempts at weight loss, possibly related to their less pronounced body dissatisfaction or fewer help-seeking behaviors as compared to females. Our results also support findings of substantial comorbidity among obesity, BED, mood and anxiety disorders, and metabolic syndrome in weight loss seeking populations, in men as well as women.

Response of Recurrent Binge Eating and Weight Gain to Topiramate in Patients with Binge Eating Disorder after Bariatric Surgery

Background: The effectiveness of topiramate was evaluated in the treatment of recurrent binge eating and weight gain in patients with binge eating disorder (BED) and obesity who had undergone initially successful bariatric surgery. Methods: The records of 3 consecutive patients with BED and obesity who presented to our clinic with recurrent binge eating and weight gain after undergoing initially successful bariatric surgery were reviewed. They were treated with topiramate for an average of 10 months. Results: All three patients reported complete amelioration of their binge eating symptoms and displayed weight loss (31.7 kg in 17 months, 14.5 kg in 9 months, 2 kg in 4 months, respectively) in response to topiramate (mean dose 541 mg). Conclusion: Although anecdotal, these observations suggest that topiramate may be an effective treatment for patients with BED and obesity who experience recurrent binge eating and weight gain after initially successful bariatric surgery.