Emotion-based decision-making in healthy subjects: short-term effects of reducing dopamine levels.

INTRODUCTION: Converging evidences from animal and human studies suggest that addiction is associated with dopaminergic dysfunction in brain reward circuits. So far, it is unclear what aspects of addictive behaviors are related to a dopaminergic dysfunction. DISCUSSION: We hypothesize that a decrease in dopaminergic activity impairs emotion-based decision-making. To demonstrate this hypothesis, we investigated the effects of a decrease in dopaminergic activity on the performance of an emotion-based decision-making task, the Iowa gambling task (IGT), in 11 healthy human subjects. MATERIALS AND METHODS: We used a double-blind, placebo-controlled, within-subject design to examine the effect of a mixture containing the branched-chain amino acids (BCAA) valine, isoleucine and leucine on prolactin, IGT performance, perceptual competency and visual aspects of visuospatial working memory, visual attention and working memory, and verbal memory. The expectancy-valence model was used to determine the relative contributions of distinct IGT components (attention to past outcomes, relative weight of wins and losses, and choice strategies) in the decision-making process. OBSERVATIONS AND RESULTS: Compared to placebo, the BCAA mixture increased prolactin levels and impaired IGT performance. BCAA administration interfered with a particular component process of decision-making related to attention to more recent events as compared to more distant events. There were no differences between placebo and BCAA conditions for other aspects of cognition. Our results suggest a direct link between a reduced dopaminergic activity and poor emotion-based decision-making characterized by shortsightedness, and thus difficulties resisting short-term reward, despite long-term negative consequences. These findings have implications for behavioral and pharmacological interventions targeting impaired emotion-based decision-making in addictive disorders.

Pharmacological treatments for first-episode schizophrenia.

Studies with first-episode populations offer the unique opportunity to examine the effectiveness and side effects of medications without the confounding effects of prior medication use. This review focuses upon studies of (1) treatment of the initial episode, (2) maintenance treatment issues, (3) recovery, and (4) side effects. Response rates for the initial episode are high with both conventional and new-generation antipsychotics. However, we lack data directly comparing the new-generation agents with one another for treatment of the initial episode, and data about options for patients with treatment resistance at illness onset are very limited. With the most commonly used pharmacological therapies, the course of early-phase schizophrenia is characterized by repeated relapses and a low rate of recovery. Medication treatment is also associated with a variety of side effects. Of particular concern for treatment of first-episode patients are the metabolic side effects with the new-generation antipsychotics because they occur rapidly, are very distressful to adolescents and young adults, and have long-term medical consequences. Available data support maintenance treatment to prevent relapse, but questions remain about the optimal duration of maintenance treatment, whether there are differences among the new-generation agents for maintenance treatment, and balancing the benefits of maintenance antipsychotics with their long-term side effects.

Incidence of tardive dyskinesia with risperidone or olanzapine in the elderly: results from a 2-year, prospective study in antipsychotic-naïve patients.

Tardive dyskinesia (TD) rates with second-generation antipsychotics (SGAs) are considered to be low relative to first-generation antipsychotics (FGAs), even in the particularly vulnerable elderly population. However, risk estimates are unavailable for patients naïve to FGAs. Therefore, we aimed to determine the TD incidence in particularly vulnerable, antipsychotic-naïve elderly patients treated with the SGA risperidone or olanzapine. The present work describes a prospective inception cohort study of antipsychotic-naïve elderly patients aged 55 years identified at New York Metropolitan area in-patient and out-patient geriatric psychiatry facilities and nursing homes at the time of risperidone or olanzapine initiation. At baseline, 4 weeks, and at quarterly periods, patients underwent assessments of medical and medication history, abnormal involuntary movements, and extra-pyramidal signs. TD was classified using Schooler-Kane criteria. Included in the analyses were 207 subjects (age: 79.8 years, 70.0% female, 86.5% White), predominantly diagnosed with dementia (58.9%) or a major mood disorder (30.9%), although the principal treatment target was psychosis (78.7%), with (59.4%) or without (19.3%) agitation. With risperidone (n=159) the cumulative TD rate was 5.3% (95% confidence interval (CI): 0.7, 9.9%) after 1 year (mean dose: 1.0±0.76 mg/day) and 7.2% (CI: 1.4, 12.9%) after 2 years. With olanzapine (n=48) the cumulative TD rate was 6.7% (CI: 0, 15.6%) after 1 year (mean dose: 4.3±1.9 mg/day) and 11.1% (CI: 0, 23.1%) after 2 years. TD risk was higher in females, African Americans, and patients without past antidepressant treatment or with FGA co-treatment. The TD rates for geriatric patients treated with risperidone and olanzapine were comparable and substantially lower than previously reported for similar patients in direct observation studies using FGAs. This information is relevant for all patients receiving antipsychotics, not just the especially sensitive elderly.