Planning deficits in polysubstance dependent users: Differential associations with severity of drug use and intelligence

BACKGROUND

Polysubstance use is associated with alterations in different components of executive functioning such as working memory and response inhibition. Nevertheless, less attention has been given to executive planning skills, which are required to benefit of low structured interventions. This study examines the association between severity of use of cocaine, heroin, alcohol, fluid and crystallized intelligence and planning tasks varying on degree of structure.

METHODS

Data were collected from 60 polysubstance users and 30 healthy controls. Cognitive assessment consisted of three planning tasks with different structure levels: Stockings of Cambridge, Zoo Map test, and Multiple Errands Test.

RESULTS

Polysubstance users had significant planning deficits across the three tasks compared to healthy controls. Hierarchical regression models showed that severity of drug use and fluid and crystallized intelligence significantly explained performance in all the planning tasks. However, these associations were higher for low-structured real world tasks. These low-structured tasks also showed a unique association with crystallized but not fluid intelligence.

CONCLUSION

Drug abuse is negatively associated with planning abilities, and intelligence is positively associated with planning performance in real-world tasks.

Self-regulation and treatment retention in cocaine dependent individuals: a longitudinal study

BACKGROUND

We aimed to explore the association between baseline executive functioning and treatment outcome in Therapeutic Communities (TCs).

METHODS

We used a longitudinal descriptive design: a baseline neuropsychological assessment was performed within the first 30 days of treatment in TCs. Once participants finished or abandoned treatment, the information about time of stay in treatment was computed for each individual. The study was conducted across six TCs located in the region of Andalusia (Spain): Cartaya, Almonte, Mijas, Los Palacios, La Línea, and Tarifa. Participants were 131 patients with cocaine dependence who initiated and finished treatment in TCs between January 2009 and December 2010 (2 years). Cognitive assessment was composed of general measures of executive functioning: Letter Number Sequencing (working memory) and Similarities (reasoning), and executive tasks sensitive to ventromedial prefrontal cortex dysfunction, including the Delis-Kaplan Stroop test (inhibition/cognitive switching), the Revised-Strategy Application Test (strategy application/multitasking), and the Iowa Gambling Task (decision-making). The outcome measure was retention, defined as time in TC treatment (number of days).

RESULTS

Poor executive functioning significantly predicted shorter treatment retention in cocaine dependent individuals on TC residential treatment (14% of explained variance). Reduced performance on the R-SAT, a multitasking test taxing the ability to develop and apply the best strategy to organize multiple sub-routine tasks in order to achieve a long-term goal, was the most powerful predictor of treatment retention.

CONCLUSIONS

Self-regulation deficits predict the capacity to remain in residential treatment among cocaine dependents.

Emotion, decision-making and substance dependence: a somatic-marker model of addiction

Similar to patients with orbitofrontal cortex lesions, substance dependent individuals (SDI) show signs of impairments in decision-making, characterised by a tendency to choose the immediate reward at the expense of severe negative future consequences. The somatic-marker hypothesis proposes that decision-making depends in many important ways on neural substrates that regulate homeostasis, emotion and feeling. According to this model, there should be a link between abnormalities in experiencing emotions in SDI, and their severe impairments in decision-making in real-life. Growing evidence from neuroscientific studies suggests that core aspects of substance addiction may be explained in terms of abnormal emotional guidance of decision-making. Behavioural studies have revealed emotional processing and decision-making deficits in SDI. Combined neuropsychological and physiological assessment has demonstrated that the poorer decision-making of SDI is associated with altered reactions to reward and punishing events. Imaging studies have shown that impaired decision-making in addiction is associated with abnormal functioning of a distributed neural network critical for the processing of emotional information, including the ventromedial cortex, the amygdala, the striatum, the anterior cingulate cortex, and the insular/somato-sensory cortices, as well as non-specific neurotransmitter systems that modulate activities of neural processes involved in decision-making. The aim of this paper is to review this growing evidence, and to examine the extent of which these studies support a somatic-marker model of addiction.

[Forensic neuropsychology at the challenge of the relationship between cognition and emotion in psychopathy]

INTRODUCTION

The relationship between frontal lobe damage and criminality is especially complex. The neural substrates of psychopathic behavior seem to involve structural and functional abnormalities in the frontal lobes and the limbic system. AIM. To analyze the repercussions that brain structural and functional abnormalities in psychopathic individuals may have for forensic neuropsychology.

DEVELOPMENT

Consistent evidence indicate that response inhibition problems in psychopathic subjects are linked to structural or functional damage in the frontal cortex. Furthermore, the prefrontal cortex, along with the amygdala and the hippocampus forms the limbic system, which is an important neural substrate of emotion processing; therefore the psychopath's capacity of affective processing could also be impaired. The theoretical frameworks of the somatic marker and mirror neuron hypotheses, along with the empirical study of executive functions may contribute to explain the inability of the psychopathic subjects to feel empathy, which is one of the main inhibitors of violence and antisocial behavior.

CONCLUSIONS

The relationship between frontal lobe dysfunction and antisocial behavior arises an important legal issue. In order to consider some type of minor liability in the case of psychopaths it is suggested to gather further research data about the relationship between frontal lobe dysfunction and the ability to inhibit antisocial behavior by making an adequate use of empathy and emotional ties.

[Neuroimaging and drug addiction: neuroanatomical correlates of cocaine, opiates, cannabis and ecstasy abuse]

INTRODUCTION

Drug abuse is related to neurocognitive alterations linked to the functioning of several areas of the brain. The application of advanced neuroimaging techniques has allowed important advances to be made in research being conducted on why stable disorders are produced in the brain mechanisms responsible for the cognitive processes and on determining exactly what mechanisms drugs of abuse are involved in. AIM. To discuss the evidence available regarding the existence of alterations in the brains of consumers of the most prevalent drugs of abuse in western societies, that is, cocaine, opiates, ecstasy and cannabis.

DEVELOPMENT

We review the main neuroimaging studies that have detected alterations in the brain structure and functioning of drug abusers. Likewise, we also discuss the findings from functional neuroimaging studies that have analysed patterns of brain activation associated to specific cognitive operations, such as memory or the executive functions.

CONCLUSIONS

Drug abusers present significant alterations in extensive areas of the cortex (especially in the frontal and temporal cortex), subcortex (amygdala, hippocampus and insular cortex) and basal regions (striatum). These alterations are associated with abnormal patterns of activation during cognitive memory tasks, inhibition and decision-making. Cocaine abusers present more pronounced and generalised alterations in the brain. By combining neuropsychological and neuroimaging findings is has been shown that the motivational, memory and executive control processes can play a key role in rehabilitating drug addicts.

[Clinical neuropsychology of the surgery of temporal lobe epilepsy]

INTRODUCTION AND OBJECTIVES

The surgery of epilepsy has become a real alternative for the treatment of patients with drug resistant epilepsy. In this study we review the part played by Clinical Neuropsychology in programmes of surgery for epilepsy, particularly in operations designed to treat drug resistant temporal lobe epilepsy.

DEVELOPMENT

Firstly we describe the function of the clinical neurologist in relation to these patients. Then we consider the main national and international forms of assessment. Finally we describe the main findings of neuropsychological investigation regarding the approach to temporal lobectomy. Thus we describe the main presurgical characteristics of candidates for surgery regarding cognition and personality. Similarly we describe what is known of the possibilities of finding the site of the epilepetogenic focus and prognosis of the results and neuropsychological consequences of the operation. Finally, we describe the cognitive results, particularly memory, after temporal lobectomy.

CONCLUSIONS

Review of the literature shows how important it is for the clinical neuropsychologist to be involved in programmes of the surgery of epilepsy, studying the patients before and after surgery and assessing prognosis. Clinical neuropsychology is also important for predicting the post surgical neuropsychological results.

[Changes in episodic and semantic memory associated with temporal lobectomy]

INTRODUCTION

Temporal lobectomy (TL) is an effective treatment for drug refractory temporal lobe epilepsy. The main neuropsychological consequences of the intervention are changes in episodic and semantic memory. Aim. To study the consequences of right temporal lobectomy (RTL) and left temporal lobectomy (LTL) on episodic and semantic mnemonic functioning.

PATIENTS AND METHOD

27 patients who had undergone TL in the Hospital Universitario Virgen de las Nieves in Granada were submitted to pre and post surgical evaluation by means of a battery of neuropsychological tests that included episodic and semantic memory tests for both verbal and visual material.

RESULTS AND CONCLUSIONS

ANOVA analysis was employed to analyse the pre and post surgical changes for the whole group of patients, and Student s t and Wilcoxon s non parametric test were used for each group of RTL and LTL. No deterioration was found in ipsilateral memory after the intervention, that is to say, in the verbal memory of the patients submitted to LTL and in the visual memory of RTL patients. With regard to contralateral memory, that is, the visual memory of patients submitted to LTL and the verbal memory of RTL patients, the ANOVA analyses of the whole group revealed a statistically significant improvement. The analyses performed for the whole group (LTL and RTL), however, did not reveal any statistically significant changes.