Kleptomania and pathological gambling (PG) are currently classified in the DSM IV as impulse control disorders. Impulse control disorders are characterized by an overwhelming temptation to perform an act that is harmful to the person or others. The patient usually feels a sense of tension before committing the act and then experiences pleasure or relief while in the process of performing the act. Kleptomania and PG are often associated with other comorbid psychiatric diagnoses. Forty-four pathological gamblers and 19 kleptomanics were included in this study. All enrolled patients underwent a complete diagnostic psychiatric evaluation and were examined for symptoms of depression and anxiety using the Hamilton depression rating scale and the Hamilton anxiety rating scale, respectively. In addition, the patients completed self-report questionnaires about their demographic status and addictive behavior. The comorbid lifetime diagnoses found at a high prevalence among our kleptomanic patients included 47% with affective disorders (9/19) and 37% with anxiety disorders (7/19). The comorbid lifetime diagnoses found at a high prevalence in our sample of pathological gamblers included 27% with affective disorders (12/44), 21% with alcohol abuse (9/44), and 7% with a history of substance abuse (3/44). A larger study is needed to confirm these preliminary results.

In this paper we continue the examination of inventory control in which the inventory is modeled by a diffusion process and a long-term average cost criterion is used to make decisions. The class of such models under consideration has general drift and diffusion coefficients, and boundary points that are consistent with the notion that demand should tend to reduce the inventory level. The conditions on the cost functions are greatly relaxed from those in Helmes et al. (2017). Characterization of the cost of a general (s, S) policy as a function of two variables naturally leads to a nonlinear optimization problem over the ordering levels s and S. Existence of an optimizing pair (s*, S*) is established for these models under very weak conditions; nonexistence of an optimizing pair is also discussed. Using average expected occupation and ordering measures and weak convergence arguments, weak conditions are given for the optimality of the (s*, S*) ordering policy in the general class of admissible policies. The analysis involves an auxiliary function that is globally C2 and which, together with the infimal cost, solves a particular system of linear equations and inequalities related to but different from the long-term average Hamilton‒Jacobi‒Bellman equation. This approach provides an analytical solution to the problem rather than a solution involving intricate analysis of the stochastic processes. The range of applicability of these results is illustrated on a drifted Brownian motion inventory model, both unconstrained and reflected, and on a geometric Brownian motion inventory model under two different cost structures.

In this paper asymptotic results in a long-term growth rate portfolio optimization model under both fixed and proportional transaction costs are obtained. More precisely, the convergence of the model when the fixed costs tend to 0 is investigated. A suitable limit model with purely proportional costs is introduced and the convergence of optimal boundaries, asymptotic growth rates, and optimal risky fraction processes is rigorously proved. The results are based on an in-depth analysis of the convergence of the solutions to the corresponding Hamilton–Jacobi–Bellman equations.

We consider a class of impulse control problems for general underlying strong Markov processes on the real line, which allows for an explicit solution. The optimal impulse times are shown to be of a threshold type and the optimal threshold is characterised as a solution of a (typically nonlinear) equation. The main ingredient we use is a representation result for excessive functions in terms of expected suprema.

The efficacy of institutional and community-based treatment services is crucial in maintaining the health, safety, and quality of life of persons with psychiatric illness. A factor limiting the success of community interventions is the rehospitalisation of persons with mental health disorders due to behavioural concerns, particularly aggression toward self and others. Understanding impulse control, a construct commonly thought to have a relationship to aggressive behaviour, may provide psychologists with insights into individual behaviour in novel or unpredictable environments. This study examines the validity of biopsychosocial assessment of impulsivity in understanding inpatient behaviour in 53 individuals currently residing in a State psychiatric facility. Using three separate measures of impulsivity, a regression analysis was used to determine the predictive value of these measures in relation to institutional behaviour. Support was found for using impulsivity assessment as a predictor of institutional behaviour. Discussion and suggestions for utilising biopsychosocial assessment of impulsivity in inpatient and community settings is provided.

Since some years it has become evident that objective disturbances can be found in patients suffering from personality disorders. Research findings from earlier date already demonstrated low levels of 5-hydroxyindoleacetic acid in the cerebrospinal fluid, especially in patients with personality disorders, under exclusion of depressive features. Furthermore, data have been collected on the correlation between a hyposerotonergic state and disturbances in aggression and impulse control in a variety of syndromes such as automutilation, bulimia nervosa, suicide attempts and various states of drug abuse.

However, psychopharmacological research in personality disorders is rare and to date mainly patients with borderline and schizotypical personality disorders have been studied. It is quite remarkable for this area to find more review articles than original contributions based on the results of clinical trials. A great variety of recommendations for pharmacotherapy in these patients exists in literature, among which treatment with carbamazepine, lithium, low-dose neuroleptics, tricyclic antidepressants and serotonin uptake inhibitors. In this article we will analyze the research methodology and the results of clinical trials forming the base for pharmacotherapeutic treatment recommendations.

Only the results of well-controlled studies will be reviewed.

We study here the impulse control minimax problem. We allow the cost functionals anddynamics to be unbounded and hence the value functions can possibly be unbounded. We provethat the value function of the problem is continuous. Moreover, the value function ischaracterized as the unique viscosity solution of an Isaacs quasi-variational inequality.This problem is in relation with an application in mathematical finance.

A zero-sum stochastic differential gameproblem on infinite horizon with continuous and impulse controls isstudied. We obtain the existence of the value of the game andcharacterize it as the unique viscosity solution of the associatedsystem of quasi-variational inequalities. We also obtain averification theorem which provides an optimal strategy of the game.

The problem of optimal dividends paid until absorbtion at zero is considered for a rather general diffusion model. With each dividend payment there is a proportional cost and a fixed cost. It is shown that there can be essentially three different solutions depending on the model parameters and the costs. (i) Whenever assets reach a barrier y*, they are reduced to y* - δ* through a dividend payment, and the process continues. (ii) Whenever assets reach a barrier y*, everything is paid out as dividends and the process terminates. (iii) There is no optimal policy, but the value function is approximated by policies of one of the two above forms for increasing barriers. A method to numerically find the optimal policy (if it exists) is presented and numerical examples are given.

We consider the portfolio optimization problem of maximizing the asymptotic growth rate under a combination of fixed and proportional costs. Expressing the asymptotic growth rate in terms of the risky fraction process, the problem can be transformed to that of controlling a diffusion in one dimension. Then we use the corresponding quasivariational inequalities to obtain the explicit shape together with the existence of an optimal impulse control strategy. This optimal strategy is given by only four parameters: two for the stopping boundaries and two for the new risky fractions the investor chooses at these times.

We consider the problem of optimally tracking a Brownian motion by a sequence of impulse controls, in such a way as to minimize the total expected cost that consists of a quadratic deviation cost and a proportional control cost. The main feature of our model is that the control can only be exerted at the arrival times of an exogenous uncontrolled Poisson process (signal). In other words, the set of possible intervention times are discrete, random and determined by the signal process (not by the decision maker). We discuss both the discounted problem and the ergodic problem, where explicit solutions can be found. We also derive the asymptotic behavior of the optimal control policies and the value functions as the intensity of the Poisson process goes to infinity, or roughly speaking, as the set of admissible controls goes from the discrete-time impulse control to the continuous-time bounded variation control.