Selective alterations within executive functions in adolescents with excess weight

Increasing evidence underscores overlapping neurobiological pathways to addiction and obesity. In both conditions, reward processing of preferred stimuli is enhanced, whereas the executive control system that would normally regulate reward-driven responses is altered. This abnormal interaction can be greater in adolescence, a period characterized by relative immaturity of executive control systems coupled with the relative maturity of reward processing systems. The aim of this study is to explore neuropsychological performance of adolescents with excess weight (n = 27, BMI range 24-51 kg/m(2)) vs. normal-weight adolescents (n = 34, BMI range 17-24 kg/m(2)) on a comprehensive battery of executive functioning tests, including measures of working memory (letter-number sequencing), reasoning (similarities), planning (zoo map), response inhibition (five-digit test (FDT)-interference and Stroop), flexibility (FDT-switching and trail-making test (TMT)), self-regulation (revised-strategy application test (R-SAT)), and decision-making (Iowa gambling task (IGT)). We also aimed to explore personality traits of impulsivity and sensitivity to reward. Independent sample t- and Z Kolmogorov-Smirnov tests showed significant differences between groups on indexes of inhibition, flexibility, and decision-making (excess-weight participants performed poorer than controls), but not on tests of working memory, planning, and reasoning, nor on personality measures. Moreover, regression models showed a significant association between BMI and flexibility performance. These results are indicative of selective alterations of particular components of executive functions in overweight adolescents.

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.

Impulsivity and executive functions in polysubstance-using rave attenders

OBJECTIVES

Rave parties are characterized by high levels of drug use and polysubstance-using patterns that may be especially harmful for psychological and neuropsychological functioning. The aim of this study was to conduct a comprehensive assessment of different aspects of impulsivity and executive functions in a sample of polysubstance-using rave attenders.

METHODS

We collected data from two groups: rave attenders (RvA, n = 25) and drug-free healthy comparison individuals (HCI, n = 27). RvA were regular users of cannabis, cocaine, methampethamine, hallucinogens, and alcohol. The assessment protocol included a drug-taking interview, the UPPS-P Impulsive Behavior Scale, the delay-discounting questionnaire and a set of neuropsychological tests taxing different aspects of executive functions: response speed, working memory, reasoning, response inhibition and switching, self-regulation, decision making, and emotion perception.

RESULTS

For impulsivity measures, RvA had significantly elevated scores on lack of perseverance and positive and negative urgency, but did not differ from controls on lack of premeditation or sensation seeking. For neuropsychological functioning, RvA had significantly poorer performance on indices of analogical reasoning, processing speed, working memory, inhibition/switching errors, and decision making, but performed similar to controls on indices of self-regulation, reversal learning, and emotion processing. Peak and binge alcohol and drug use were positively correlated with positive urgency, and negatively correlated with performance on executive indices.

CONCLUSION

Rave attenders have selective alterations of impulsive personality and executive functions. These findings can contribute to delineate the neuropsychological profiles that distinguish recreational polysubstance use from substance dependence.

Impact of severity of drug use on discrete emotions recognition in polysubstance abusers

Neuropsychological studies support the association between severity of drug intake and alterations in specific cognitive domains and neural systems, but there is disproportionately less research on the neuropsychology of emotional alterations associated with addiction. One of the key aspects of adaptive emotional functioning potentially relevant to addiction progression and treatment is the ability to recognize basic emotions in the faces of others. Therefore, the aims of this study were: (i) to examine facial emotion recognition in abstinent polysubstance abusers, and (ii) to explore the association between patterns of quantity and duration of use of several drugs co-abused (including alcohol, cannabis, cocaine, heroin and MDMA) and the ability to identify discrete facial emotional expressions portraying basic emotions. We compared accuracy of emotion recognition of facial expressions portraying six basic emotions (measured with the Ekman Faces Test) between polysubstance abusers (PSA, n=65) and non-drug using comparison individuals (NDCI, n=30), and used regression models to explore the association between quantity and duration of use of the different drugs co-abused and indices of recognition of each of the six emotions, while controlling for relevant socio-demographic and affect-related confounders. Results showed: (i) that PSA had significantly poorer recognition than NDCI for facial expressions of anger, disgust, fear and sadness; (ii) that measures of quantity and duration of drugs used significantly predicted poorer discrete emotions recognition: quantity of cocaine use predicted poorer anger recognition, and duration of cocaine use predicted both poorer anger and fear recognition. Severity of cocaine use also significantly predicted overall recognition accuracy.

[Neuropsychology of executive functions]

The aim of this text is to discuss the state of science in the neuropsychology of executive functions, defined as higher-order skills involved in the energization, regulation, sound execution and on-line readjustment of goal-directed behaviors. To reach this aim, we conducted a theoretical review of contemporary models of executive functions, their neural substrates and dynamic organization and the headways in neuropsychological assessment. We provide an updated integrative overview of the theoretical accounts and clinical advances of neuropsychological research on executive functions following a multicomponent approach, which posits that executive functions encompass several interactive executive subprocesses. We conclude that executive functions constitute mechanisms of inter-modal and inter-temporal integration that allow us to project cognitions and emotions towards future scenarios in order to best resolve novel complex situations. We currently have a well-grounded set of neuropsychological instruments able to characterize the competence of a number of executive subprocesses and their dynamic interaction and theoretical models ready to guide potential advances in their understanding.

[Neuropsychology of impulsive aggression]

INTRODUCTION

Structural and functional abnormalities of the cerebral circuits involved in affect regulation are associated with the display of violent behaviors. The prefrontal cortex hypofunction linked to the subcortical structural hyperactivity is related to impulsive aggression.

AIM

To review the current state of the neuropsychological studies concerning the possible dysfunctions in individuals who show violent and antisocial behaviors, considering the contributions for prevention and treatment.

DEVELOPMENT

There is more and more evidence in favour of a neuroanatomical substrate which may represent a vulnerability factor in the expression of aggressive and antisocial behaviors. Recent studies with neuroimaging techniques show the crucial role of the prefrontal cortex and the limbic system, which are cerebral circuits in charge of affect regulation and the origins of impulsive aggressive behaviors. The importance of the functional balance of these regions is highlighted, as well as the role of impulsivity and abnormal affect control in the display of these behaviors. In addition, a view of differential underlying mechanisms of impulsive and premeditated aggression is supported.

CONCLUSIONS

The study of the possible neuroanatomical and functional substrates of the impulsive aggressive behaviors, linked to the study of the psychosocial factors may be relevant from neuropsychological perspective. This comprehensive view may contribute to a better understanding of antisocial behavior.

[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.

A somatic marker theory of addiction

Similar to patients with ventromedial prefrontal cortex (VMPC) lesions, substance abusers show altered decision-making, characterized by a tendency to choose the immediate reward, at the expense of negative future consequences. The somatic marker model proposes that decision-making depends on neural substrates that regulate homeostasis, emotion and feeling. According to this model, there should be a link between alterations in processing emotions in substance abusers, and their impairments in decision-making. Growing evidence from neuroscientific studies indicate that core aspects of addiction may be explained in terms of abnormal emotional/homeostatic guidance of decision-making. Behavioral studies have revealed emotional processing and decision-making deficits in substance abusers. Neuroimaging studies have shown that altered decision-making in addiction is associated with abnormal functioning of a distributed neural network critical for the processing of emotional information, and the experience of "craving", including the VMPC, 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 to which these studies support a somatic marker theory of addiction. We conclude that there are at least two underlying types of dysfunction where emotional signals (somatic markers) turn in favor of immediate outcomes in addiction: (1) a hyperactivity in the amygdala or impulsive system, which exaggerates the rewarding impact of available incentives, and (2) hypoactivity in the prefrontal cortex or reflective system, which forecasts the long-term consequences of a given action.

Dysregulation of emotional response in current and abstinent heroin users: negative heightening and positive blunting

OBJECTIVE

Evidence suggests that abstinent opioid users have abnormal emotional response to natural reinforcing stimuli, but little is known about the emotional response of subjects currently using heroin. Abnormal emotional experience could underlie poor sensitivity to negative events related to heroin use and reduced ability to consider alternative reinforcers to help overcome addiction. In this paper, we will assess the subjective response of current and abstinent heroin users exposed to emotionally competent positive and negative stimuli.

MATERIALS AND METHODS

We administered the "Clinical Instrument for Emotional Response Evaluation" (including neutral, pleasant, and unpleasant images from the International Affective Picture System) to 22 current opioid users enrolled in a clinical trial using controlled prescribed heroin and 41 abstinent opioid users enrolled in residential treatment. The dependent variable was their subjective response to the images measured with the Self-Assessment Manikin, a scale designed to rate the International Affective Picture System (IAPS) images in the three dimensions of emotion: valence, arousal, and dominance. We compared these ratings with IAPS normative values for healthy participants.

RESULTS

Significant group x emotional condition interactions were found in the arousal dimension. Post-hoc tests showed that compared to healthy participants, both current and abstinent heroin users had greater emotional response to neutral images and lower response to pleasant images. Furthermore, current opioid users had higher emotional response to unpleasant images when compared to healthy participants and lower response to pleasant images when compared to abstinent users.

CONCLUSIONS

Current opioid users have abnormal emotional experience, characterized by heightened response to unpleasant stimuli and blunted response to pleasant stimuli.

Substance abusers' self-awareness of the neurobehavioral consequences of addiction

Substance abusers (SA) usually deny or are not aware that they have a problem. Recent neuro-scientific evidence suggests that denial of problems related to drug use can be associated with alterations in frontostriatal systems, which play a critical role in executive functions and self-awareness. In this study, we examined self-awareness of cognitive deficits, which may be indicative of frontostriatal involvement, in a sample of abstinent SA. We administered the self and informant rating forms of the Frontal Systems Behavior Scale (FrSBe) to 38 SA and to 38 designated informants. We conducted three separate mixed design ANOVAs to contrast the discrepancy between SA and informant scores on the three FrSBe subscales both during drug abuse (assessed retrospectively) and during abstinence. We conducted regression analyses to examine the relationship between severity of drug abuse and self-awareness. Results showed that informants' scores were significantly higher than SA's scores on apathy and executive dysfunction during drug abuse, indicating poor awareness of deficits. We found no significant discrepancies between SA's and informants' scores during abstinence. Severity of alcohol and cocaine abuse significantly predicted poorer self-awareness during drug abuse, but not during abstinence. These results may have important implications for prevention and treatment strategies.

Impulsivity as a vulnerability marker for substance-use disorders: review of findings from high-risk research, problem gamblers and genetic association studies

There is a longstanding association between substance-use disorders (SUDs) and the psychological construct of impulsivity. In the first section of this review, personality and neurocognitive data pertaining to impulsivity will be summarised in regular users of four classes of substance: stimulants, opiates, alcohol and 3,4-methylenedioxymethamphetamine (MDMA). Impulsivity in these groups may arise via two alternative mechanisms, which are not mutually exclusive. By one account, impulsivity may occur as a consequence of chronic exposure to substances causing harmful effects on the brain. By the alternative account, impulsivity pre-dates SUDs and is associated with the vulnerability to addiction. We will review the evidence that impulsivity is associated with addiction vulnerability by considering three lines of evidence: (i) studies of groups at high-risk for development of SUDs; (ii) studies of pathological gamblers, where the harmful consequences of the addiction on brain structure are minimised, and (iii) genetic association studies linking impulsivity to genetic risk factors for addiction. Within each of these three lines of enquiry, there is accumulating evidence that impulsivity is a pre-existing vulnerability marker for SUDs.

Negative emotion-driven impulsivity predicts substance dependence problems

Impulsivity is predominant among users of several drugs of abuse including alcohol, cocaine, and amphetamines, and it is considered a risk factor for later development of alcohol and substance abuse and dependence. However, there is little consensus on how impulsivity should be defined and measured, and there are few studies on the relationship between separate dimensions of impulsivity and substance dependence. We used a multidimensional measure of impulsivity (the UPPS scale) to examine differences between 36 individuals with substance dependence (ISD) and 36 drug-free controls on the dimensions of urgency, lack of premeditation, lack of perseverance, and sensation seeking. In addition, we examined which dimensions of impulsivity better predicted addiction-related problems as measured with the addiction severity index. Results revealed that ISD show high scores on dimensions of urgency, lack of perseverance, and lack of premeditation (effect sizes ranging from 1.10 to 1.96), but not on sensation seeking. Among the different impulsivity dimensions, urgency was the best predictor of severity of medical, employment, alcohol, drug, family/social, legal and psychiatric problems in ISD, explaining 13-48% of the total variance of these indices. Furthermore, urgency scores alone correctly classified 83% of the participants in the ISD group. Urgency is characterized by a tendency to act impulsively in response to negative emotional states. Thus, our results could have important implications for novel treatment approaches for substance dependence focused on emotional regulation.

Ecological assessment of executive functions in substance dependent individuals

Substance dependence is associated with executive function deficits. However, most available studies have examined the performance of substance dependent individuals (SDI) on traditional laboratory measures of executive functions, whereas few studies have used ecologically valid assessments with SDI. Our aim was to examine the performance of 37 SDI (poly-substance users) and 37 matched controls on an ecologically valid measure of executive function (the Behavioural Assessment of the Dysexecutive Syndrome - BADS). We also administered the Wisconsin Card Sorting Test (WCST) to investigate whether ecological measures were more discriminative than traditional tests in detecting SDI deficits. A related aim was to examine the ability of the BADS (and the WCST) to predict everyday executive problems. Results showed that SDI had widespread deficits on ecological measures of executive function. Conversely, we found no differences between groups on the WCST. Furthermore, the BADS (but not the WCST) predicted everyday problems related to apathy, disinhibition, and executive dysfunction.

[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.

Profile of executive deficits in cocaine and heroin polysubstance users: common and differential effects on separate executive components

OBJECTIVES

Structure of executive function was examined and we contrasted performance of substance dependent individuals (polysubstance users) and control participants on neuropsychological measures assessing the different executive components obtained. Additionally, we contrasted performance of polysubstance users with preference for cocaine vs heroin and controls to explore possible differential effects of the main substance abused on executive impairment.

METHODS

Two groups of participants were recruited: abstinent polysubstance users and controls. Polysubstance users were further subdivided based on their drug of choice (cocaine vs heroin). We administered to all participants a comprehensive protocol of executive measures, including tests of fluency, working memory, reasoning, inhibitory control, flexibility, and decision making.

RESULTS

Consistent with previous models, the principal component analysis showed that executive functions are organized into four separate components, three of them previously described: updating, inhibition, and shifting; and a fourth component of decision making. Abstinent polysubstance users had clinically significant impairments on measures assessing these four executive components (with effect sizes ranging from 0.5 to 2.2). Cocaine polysubstance users had more severe impairments than heroin users and controls on measures of inhibition (Stroop) and shifting (go/no go and category test). Greater severity of drug use predicted poorer performance on updating measures.

CONCLUSION

Executive functions can be fractionated into four relatively independent components. Chronic drug use is associated with widespread impairment of these four executive components, with cocaine use inducing more severe deficits on inhibition and shifting. These findings show both common and differential effects of two widely used drugs on different executive components.

Strategic self-regulation, decision-making and emotion processing in poly-substance abusers in their first year of abstinence

Individuals with substance dependence (ISD) frequently show signs of impaired emotion processing, self-regulation and decision-making, even after prolonged abstinence from drug use and partial recovery of other neuropsychological functions. These impairments have been associated with alterations in the orbitofrontal cortex (OFC) in lesion and imaging studies. The aim of this study was to examine the performance of a group of ISD, who had been abstinent for at least 4 months, on a series of emotional perception, self-regulation and decision-making tests sensitive to OFC dysfunction. Thirty ISD (poly-substance abusers in their first year of abstinence) and 35 healthy comparison (HC) participants were in the study. We administered the Ekman Faces Test (EFT), the Revised Strategy Application Test (R-SAT) and the Iowa Gambling Task (IGT) to both ISD and HC. Results showed that the ISD presented significant deficits in the recognition of facial emotional expressions and decision-making as measured by the EFT and the IGT. The ISD also showed poorer strategy awareness, impaired self-regulation and higher impulsivity on the R-SAT. We found significant correlations between the different measures linked to OFC functioning. We did not find significant correlations between length of abstinence and performance on these tests. These results suggest that the evaluation of emotion, self-regulation and decision-making contributes greatly to the characterization of the persistent deficits exhibited by ISD during prolonged abstinence.

Differential impact of severity of drug use on frontal behavioral symptoms

Increasing evidence indicates that substance abusers are impaired in cognitive-executive control tasks relying on different functional systems converging in the prefrontal cortex (PFC). Different PFC functional systems relevant to addiction have been described: the dorsolateral (DLC), orbitofrontal (OFC), and anterior cingulate (ACC) circuits. Each system is associated with different behavioral, cognitive, and emotional deficits, including apathy, disinhibition, and executive dysfunction. In this study, we examined the effects of severity of use of different drugs on apathy, disinhibition and executive dysfunction behavioral deficits as measured by the Frontal Systems Behavior Scale (FrSBe). The FrSBe, and a severity of substance use interview were administered to 32 poly-substance abusers. Multiple regression analyses showed that severity of cannabis use significantly predicted greater apathy and executive dysfunction behavior; and that severity of cocaine use significantly predicted greater disinhibition behavior. These results are consistent with previous studies using cognitive measures and support the notion that severity of substance use significantly affects behavioral symptoms associated with PFC systems functioning. These clinical symptoms should be specifically addressed during rehabilitation.

Executive dysfunction in substance dependent individuals during drug use and abstinence: an examination of the behavioral, cognitive and emotional correlates of addiction

Increasing evidence indicates that substance-dependent individuals (SDI) are impaired in executive control tasks relying on different systems within the prefrontal cortex (PFC). Three different functional systems have been described: the dorsolateral prefrontal cortex (DLPC), orbitofrontal cortex (OFC), and anterior cingulate cortex (ACC) circuits. Dysfunction within each PFC system is associated with different behavioral, cognitive, and emotional abnormalities. Few studies have conducted an exhaustive examination of all these different factors in SDI. In this study, SDI (including alcohol, cocaine, and methamphetamine polysubstance users, n=35) were compared with healthy controls (n=36) on a series of behavioral (Frontal Systems Behaviour Scale, FrSBe), cognitive (N-back, Go-No Go, and Wisconsin Card Sorting Tasks), and emotional (International Affective Picture System, IAPS) tasks, each of which was thought to tax a different component of these PFC functional systems. SDI showed greater behavioral problems in the apathy, disinhibition, and executive dysfunction subscales of the FrSBe. Behavioral deficits were significantly associated with several real-life domains in which SDI typically have problems. SDI also showed poorer performance on cognitive tests of working memory, response inhibition and mental flexibility, and abnormal processing of affective images from the IAPS. Cognitive, behavioral, and emotional measures were moderately correlated.

Altered adaptive but not veridical decision-making in substance dependent individuals

Drug addiction is associated with impaired judgment in unstructured situations in which success depends on self-regulation of behavior according to internal goals (adaptive decision-making). However most executive measures are aimed at assessing decision-making in structured scenarios, in which success is determined by external criteria inherent to the situation (veridical decision-making). The aim of this study was to examine the performance of Substance Abusers (SA, n = 97) and Healthy Comparison participants (HC, n = 81) in two behavioral tasks that mimic the uncertainty inherent in real-life decision-making: the Cognitive Bias Task (CB) and the Iowa Gambling Task (IGT) (administered only to SA). A related goal was to study the interdependence between performances on both tasks. We conducted univariate analyses of variance (ANOVAs) to contrast the decision-making performance of both groups; and used correlation analyses to study the relationship between both tasks. SA showed a marked context-independent decision-making strategy on the CB's adaptive condition, but no differences were found on the veridical conditions in a subsample of SA (n = 34) and HC (n = 22). A high percentage of SA (75%) also showed impaired performance on the IGT. Both tasks were only correlated when no impaired participants were selected. Results indicate that SA show abnormal decision-making performance in unstructured situations, but not in veridical situations.

Experience of emotions in substance abusers exposed to images containing neutral, positive, and negative affective stimuli

There is emerging evidence that suggests emotional processes may be involved in the development of addiction, and that emotional alterations may compromise the effectiveness of treatment approaches in substance abuse. Nonetheless, there is a dearth of studies that have examined the experience of emotions in substance abusers, especially with regard to natural affective stimuli that are motivationally relevant for the normal population. The main aims of this study are: (a) to examine possible differences in the experience of emotions of drug-free substance abusers exposed to images containing motivationally relevant stimuli, with regard to a normal population and (b) to examine possible differences in the experience of emotions of substance abusers depending on their drug of choice. We used 25 images from the International Affective Picture System (IAPS) to elicit different emotional states, and the Self Assessment Manikin (SAM) to record participants' subjective experience on three emotional dimensions: valence, arousal, and dominance. We used bifactorial MANOVA to examine subjective emotional ratings as a function of group, and as a function of the kind of image shown. Results showed a differential emotional profile of substance abusers with regard to healthy controls; and different emotional profiles between abusers of a number of substances. These results suggest the experience of emotions may be significantly altered in substance abusers, and that these alterations may play an important role in drug abuse treatment course and results.

Clinical Implications and Methodological Challenges in the Study of the Neuropsychological Correlates of Cannabis, Stimulant, and Opioid Abuse

Chronic consumption of several drugs of abuse (cannabis, stimulants, opioids) has been associated with the presence of neuropsychological impairments in a broad range of functions. Nevertheless, in recent years neuropsychological research on substance abuse has focused on the study of impairments in the executive functions linked to the prefrontal cortex and their influence on the personality, cognitions, and behaviors of the substance abusers. The aim of our review is, first, to summarize the main neuropsychological impairments shown by classic studies, as well as these new discoveries in executive functioning; second, to consider the mediating role of neuropsychological status on treatment outcomes and analyze the impact of these impairments in clinical practice with drug addicts; and third, to review the principal methodological challenges associated with research in the field of the neuropsychology of substance abuse. We also highlight the convenience of intervening in those functions most relevant to the abusers' persistence in consumption and risk of relapse.

[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.