Alan M. Safer

Prolactin Serum Concentrations During Aripiprazole Treatment in Youth

OBJECTIVE This study aimed to: document the extent of the reduction of serum prolactin (PRL) levels induced by aripiprazole (ARI) treatment in children and adolescents, compare this effect by age group, and shed light on this phenomenon. METHODS PRL serum levels in unmedicated subjects were compared to those in subjects treated with aripiprazole to calculate the rate of subnormal PRL levels during aripiprazole treatment. Next, a literature search was performed to better understand the effects of dopaminergic drugs on PRL levels by age group. RESULTS Sixty percent of those treated with aripiprazole exhibited subnormal PRL serum levels versus 8% of unmedicated subjects. The rate of PRL subnormality in response to aripiprazole was half as frequent in adolescents and was minimal in adults. The drug-induced reduction of PRL serum levels became more prominent with increasing doses of aripiprazole and with an increased treatment duration. CONCLUSIONS With the increasing use of aripiprazole in the United States population, it is important that future research be conducted to explore the potential sequelae of subnormal PRL serum levels in children and adolescents.

Age-grouped differences in bipolar mania

OBJECTIVE This review of published studies compares scores on individual items of mania rating scales that systematically recorded symptom severity in persons diagnosed with bipolar disorder to identify age-grouped differences. METHODS An extensive literature search identified item scores from mania rating scales, with a particular emphasis on baseline Young Mania Rating Scale (YMRS) item scores in published double-blind, placebo-controlled studies of bipolar I manic disorder. These baseline YMRS item scores were assessed as a proportion of the total YMRS score and compared by age group. Additional YMRS item/total scores in subjects with bipolar spectrum disorders were added to expand the analysis. RESULTS Preadolescents with bipolar disorder had significantly higher YMRS item scores than adolescents on aggression, irritability, and motor activity. Young Mania Rating Scale baseline item scores relative to the YMRS total score revealed that adolescents diagnosed with bipolar I mania scored comparatively higher than did adults on YMRS aggression and irritability items, whereas adults with bipolar I manic disorder scored comparatively higher on the grandiosity and sexual interest items. Age-grouped findings from subjects diagnosed with bipolar I, II, and Not Otherwise Specified (NOS) disorders yielded similar age-grouped results. CONCLUSION In age-grouped YMRS item assessments of bipolar mania, anger dyscontrol was most prominent for youth, whereas disordered thought content was paramount for adults.

Using neural networks to predict abnormal returns of quarterly earnings

Artificial neural networks are used in conjunction with the Sharpe-Linter form of the capital asset pricing method to predict when the returns on US stocks will be greater than financial risk models would predict. The advantage of using a nonlinear approach is to model the financial system more accurately than linear techniques. The Sharpe-Lintner form is used to control risk and determine abnormal returns of stocks. Inputs include ratios of recent to past stock price averages over pre-event time periods, similarly, stock volume ratios, and previous quarter standardized unexpected earnings. The earnings data is quarterly and runs from the first quarter of 1993 to the second quarter of 1998. Event periods that had the smallest width around the earnings report tended to be easier to predict abnormal returns. In addition, event periods that were closest to the event (the earnings report) were more accurate at predicting the abnormal returns of stocks.

The effect of multiple anchors on the distribution of responses

Abstract Anchoring studies generally use high and low numerical estimates, or prompts, (identified as anchors) to introduce bias in the subsequent responses of those questioned. In this study, 700 students attending a university were equally divided into a control (no-anchor) group and six anchor groups. The numerical range of estimates (reference points) given to the anchor groups prior to their response was based on the responses of the control (no-anchor) group, which had been set at the 25, 50, 75, 85, 87, and 88 percentiles. With each increase in the prompts given to the anchor groups, there was a prominent increase in the central tendency (median) of their responses. In addition, there was an exponential increase in the spread as measured by the distance between the 75th percentile (i.e., third quartile, Q3) and the 25th percentile, (i.e., first quartile, Q1) of their responses. It is recommended that future anchor studies include a wide range of anchor percentiles and report the spread of the resulting distributions.

Multivariate adaptive regression splines and insider trading data for stock prediction

Abstract Data mining statistical techniques have not been used to improve the prediction of abnormal stock returns using insider trading data (except for one preliminary study by the author using neural networks). To expand data mining statistical research in this area, an investigation using Multivariate Adaptive Regression Splines (MARS) was initiated. The investigated covered 343 companies for a period of 4.5 years. Study findings revealed that the prediction of abnormal returns could be enhanced in the following ways : (1) extending the time of the future forecast up to 1 year ; (2) increasing the period of back aggregated data up to 4 months ; and (3) narrowing the assessment to certain industries such as electronic equipment and business services.