D��ficits y sesgos neurocognitivos y afectivos en la toma de decisiones de jugadores patol��gios y otros trastornos

Los d��ficits y sesgos tanto cognitivos como afectivos han sido fuente creciente de inter��s en el ��mbito de la Neuroci��ncia de los Trastornos Mentales. En este proyecto, que se inicia en 2004 y finaliza a finales de 2008, se han estudiado los siguientes Trastornos Mentales: Juego Patol��gico (JP), Trastornos de la Conducta Alimentaria (TCA) y Trastornos Depresivos. En esta memoria nos centraremos en resumir parte de los resultados obtenidos en un estudio sobre JP y toma de decisiones (articulo en revisi��n y pendiente de aceptaci��n) y otro de funcionamiento ejecutivo en JP y Bulimia Nerviosa (BN) (art��culo en prensa). Resumiento el primer estudio los JP (N=32) muestran un proceso de toma de decisiones sesgado por la b��squeda de recompensa en forma de elevada toma de riesgos en comparaci��n con Controles Sanos (CS). Tambi��n se observan d��ficits en flexibilidad cognitiva pero no en control inhibitorio entre JP y CS. Los resultados descartan miop��a conductual para lo toma de decisiones en JP, pero apuntan a un sesgo cognitivo-afectivo, en el que el control de los impulsos jugar��a un papel relevante, en forma de ilusi��n de control, para los procesos de toma de decisiones con recompensa inmediata pero con castigo diferido, medidos por una prueba de toma de decisiones (IGT ABCD). En el segundo estudio, bas��ndose en las vulnerabilidadades compartidas descritas entre JP y BN se compar�� el funcionamiento ejecutivo de mujeres con JP y BN. Tras la administraci��n del WCST y Stroop y ajustando el an��lisis por edad y educaci��n, las JP mostraron mayor afectaci��n, en concreto mayor porcentaje de errores perservaritvos, menor nivel de respuestas conceptuales y mayor n��mero de ensayos administrados, mientras que el grupo de BN mostr�� mayor porcentaje de errores no persevarativos. Ambas, mujeres JP y BN mostraron disfunci��n ejecutiva en relaci��n a los CS pero con diferentes correlatos espec��fcos.

D��pendances: nouveaut��s en m��decine 2008 [Addiction]

L'actualit�� 2008 des d��pendances est centr��e sur l'avanc��e des neurosciences psychiatriques dans le domaine des addictions mais aussi sur les clarifications n��cessaires face �� la complexit�� des comorbidit��s psychiatriques des addictions, notamment en cas de schizophr��nie. Enfin, le praticien trouvera des consid��rations utiles pour la prescription de traitements de substitution chez des patients VIH en trith��rapie. The highlights 2008 in the addiction field are correlated to the progress of psychiatric neurosciences. Clarifications are also necessary towards the psychiatric comorbidities (schizophrenia) with the addictions. Then, useful considerations are given for the prescription of substitution treatment among HIV patients under tritherapy.

Role of disease activity for decision making ability in early multiple sclerosis

Background and purpose: Decision making (DM) has been defined as the process through which a person forms preferences, selects and executes actions, and evaluates the outcome related to a selected choice. This ability represents an important factor for adequate behaviour in everyday life. DM impairment in multiple sclerosis (MS) has been previously reported. The purpose of the present study was to assess DM in patients with MS at the earliest clinically detectable time point of the disease. Methods: Patients with definite (n=109) or possible (clinically isolated syndrome, CIS; n=56) MS, a short disease duration (mean 2.3 years) and a minor neurological disability (mean EDSS 1.8) were compared to 50 healthy controls aged 18 to 60 years (mean age 32.2) using the Iowa Gambling Task (IGT). Subjects had to select a card from any of 4 decks (A/B [disadvantageous]; C/D [advantageous]). The game consisted of 100 trials then grouped in blocks of 20 cards for data analysis. Skill in DM was assessed by means of a learning index (LI) defined as the difference between the averaged last three block indexes and first two block indexes (LI=[(BI-3+BI-4+BI-5)/3-(BI-1+B2)/2]). Non parametric tests were used for statistical analysis. Results: LI was higher in the control group (0.24, SD 0.44) than in the MS group (0.21, SD 0.38), however without reaching statistical significance (p=0.7). Interesting differences were detected when MS patients were grouped according to phenotype. A trend to a difference between MS subgroups and controls was observed for LI (p=0.06), which became significant between MS subgroups (p=0.03). CIS patients who confirmed MS diagnosis by presenting a second relapse after study entry showed a dysfunction in the IGT in comparison to the other CIS (p=0.01) and definite MS (p=0.04) patients. In the opposite, CIS patients characterised by not entirely fulfilled McDonald criteria at inclusion and absence of relapse during the study showed an normal learning pattern on the IGT. Finally, comparing MS patients who developed relapses after study entry, those who remained clinically stable and controls, we observed impaired performances only in relapsing patients in comparison to stable patients (p=0.008) and controls (p=0.03). Discussion: These results raise the assumption of a sustained role for both MS relapsing activity and disease heterogeneity (i.e. infra-clinical severity or activity of MS) in the impaired process of decision making.

D��pendances [Addiction]

This year review emphasizes four aspects coming from addiction psychiatry: 1. Initiation and maintenance of cannabis use. 2. Methadone and heart toxicity. 3. Suicidal behaviour in gambling. 4. Treatment of addictive disorders via internet: present and future perspectives.

Essays in higher moment asset pricing and liquidity risk

This thesis focuses on theoretical asset pricing models and their empirical applications. I aim to investigate the following noteworthy problems: i) if the relationship between asset prices and investors' propensities to gamble and to fear disaster is time varying, ii) if the conflicting evidence for the firm and market level skewness can be explained by downside risk, Hi) if costly learning drives liquidity risk. Moreover, empirical tests support the above assumptions and provide novel findings in asset pricing, investment decisions, and firms' funding liquidity. The first chapter considers a partial equilibrium model where investors have heterogeneous propensities to gamble and fear disaster. Skewness preference represents the desire to gamble, while kurtosis aversion represents fear of extreme returns. Using US data from 1988 to 2012, my model demonstrates that in bad times, risk aversion is higher, more people fear disaster, and fewer people gamble, in contrast to good times. This leads to a new empirical finding: gambling preference has a greater impact on asset prices during market downturns than during booms. The second chapter consists of two essays. The first essay introduces a foramula based on conditional CAPM for decomposing the market skewness. We find that the major market upward and downward movements can be well preadicted by the asymmetric comovement of betas, which is characterized by an indicator called "Systematic Downside Risk" (SDR). We find that SDR can efafectively forecast future stock market movements and we obtain out-of-sample R-squares (compared with a strategy using historical mean) of more than 2.27% with monthly data. The second essay reconciles a well-known empirical fact: aggregating positively skewed firm returns leads to negatively skewed market return. We reconcile this fact through firms' greater response to negative maraket news than positive market news. We also propose several market return predictors, such as downside idiosyncratic skewness. The third chapter studies the funding liquidity risk based on a general equialibrium model which features two agents: one entrepreneur and one external investor. Only the investor needs to acquire information to estimate the unobservable fundamentals driving the economic outputs. The novelty is that information acquisition is more costly in bad times than in good times, i.e. counter-cyclical information cost, as supported by previous empirical evidence. Later we show that liquidity risks are principally driven by costly learning. R��sum�� Cette th��se pr��sente des mod��les th��oriques d��valuation des actifs et leurs applications empiriques. Mon objectif est d'��tudier les probl��mes suivants: la relation entre l'��valuation des actifs et les tendances des investisseurs �� parier et �� crainadre le d��sastre varie selon le temps ; les indications contraires pour l'entreprise et l'asym��trie des niveaux de march�� peuvent ��tre expliqu��es par les risques de perte en cas de baisse; l'apprentissage co��teux augmente le risque de liquidit��. En outre, des tests empiriques confirment les suppositions ci-dessus et fournissent de nouvelles d��couvertes en ce qui concerne l'��valuation des actifs, les d��cisions relatives aux investissements et la liquidit�� de financement des entreprises. Le premier chapitre examine un mod��le d'��quilibre o�� les investisseurs ont des tendances h��t��rog��nes �� parier et �� craindre le d��sastre. La pr��f��rence asym��trique repr��sente le d��sir de parier, alors que le kurtosis d'aversion repr��sente la crainte du d��sastre. En utilisant les donn��es des Etats-Unis de 1988 �� 2012, mon mod��le d��montre que dans les mauvaises p��riodes, l'aversion du risque est plus grande, plus de gens craignent le d��sastre et moins de gens parient, conatrairement aux bonnes p��riodes. Ceci m��ne �� une nouvelle d��couverte empirique: la pr��f��rence relative au pari a un plus grand impact sur les ��valuations des actifs durant les ralentissements de march�� que durant les booms ��conomiques. Exploitant uniquement cette relation g��n��rera un revenu exc��dentaire annuel de 7,74% qui n'est pas expliqu�� par les mod��les factoriels populaires. Le second chapitre comprend deux essais. Le premier essai introduit une foramule base sur le CAPM conditionnel pour d��composer l'asym��trie du march��. Nous avons d��couvert que les mouvements de hausses et de baisses majeures du march�� peuvent ��tre pr��dits par les mouvements communs des b��tas. Un inadicateur appel�� Systematic Downside Risk, SDR (risque de ralentissement syst��matique) est cr���� pour caract��riser cette asym��trie dans les mouvements communs des b��tas. Nous avons d��couvert que le risque de ralentissement syst��matique peut pr��voir les prochains mouvements des march��s boursiers de mani��re efficace, et nous obtenons des carr��s R hors ��chantillon (compar��s avec une strat��gie utilisant des moyens historiques) de plus de 2,272% avec des donn��es mensuelles. Un investisseur qui ��value le march�� en utilisant le risque de ralentissement syst��matique aurait obtenu une forte hausse du ratio de 0,206. Le second essai fait cadrer un fait empirique bien connu dans l'asym��trie des niveaux de march et d'entreprise, le total des revenus des entreprises positiveament asym��triques conduit �� un revenu de march�� n��gativement asym��trique. Nous d��composons l'asym��trie des revenus du march�� au niveau de l'entreprise et faisons cadrer ce fait par une plus grande r��action des entreprises aux nouvelles n��gatives du march�� qu'aux nouvelles positives du march��. Cette d��composition r��v��l�� plusieurs variables de revenus de march�� efficaces tels que l'asym��trie caract��ristique pond��r��e par la volatilit�� ainsi que l'asym��trie caract��ristique de ralentissement. Le troisi��me chapitre fournit une nouvelle base th��orique pour les probl��mes de liquidit�� qui varient selon le temps au sein d'un environnement de march�� incomplet. Nous proposons un mod��le d'��quilibre g��n��ral avec deux agents: un entrepreneur et un investisseur externe. Seul l'investisseur a besoin de connaitre le v��ritable ��tat de l'entreprise, par cons��quent, les informations de paiement coutent de l'argent. La nouveaut�� est que l'acquisition de l'information coute plus cher durant les mauvaises p��riodes que durant les bonnes p��riodes, comme cela a ��t�� confirm�� par de pr��c��dentes exp��riences. Lorsque la r��cession comamence, l'apprentissage co��teux fait augmenter les primes de liquidit�� causant un probl��me d'��vaporation de liquidit��, comme cela a ��t�� aussi confirm�� par de pr��c��dentes exp��riences.

Preserved decision making ability in early multiple sclerosis.

BACKGROUND: The purpose of this study was to assess decision making in patients with multiple sclerosis (MS) at the earliest clinically detectable time point of the disease. METHODS: Patients with definite MS (n = 109) or with clinically isolated syndrome (CIS, n = 56), a disease duration of 3 months to 5 years, and no or only minor neurological impairment (Expanded Disability Status Scale [EDSS] score 0-2.5) were compared to 50 healthy controls using the Iowa Gambling Task (IGT). RESULTS: The performance of definite MS, CIS patients, and controls was comparable for the two main outcomes of the IGT (learning index: p = 0.7; total score: p = 0.6). The IGT learning index was influenced by the educational level and the co-occurrence of minor depression. CIS and MS patients developing a relapse during an observation period of 15 months dated from IGT testing demonstrated a lower learning index in the IGT than patients who had no exacerbation (p = 0.02). When controlling for age, gender and education, the difference between relapsing and non-relapsing patients was at the limit of significance (p = 0.06). CONCLUSION: Decision making in a task mimicking real life decisions is generally preserved in early MS patients as compared to controls. A possible consequence of MS relapsing activity in the impairment of decision making ability is also suspected in the early phase of MS.

Percepci��n de las consecuencias del consumo de tabaco en fumadores adictos al juego

En una muestra de 34 adictos al juego en tratamiento, se examinan las caracter��sticas deconsumo de tabaco de los sujetos fumadores y la influencia de las consecuencias percibidas dela conducta de fumar en funci��n de las etapas de cambio (Prochaska, DiClemente y Norcross,1992). Los resultados muestran que, aunque los porcentajes de fumadores doblan a los existentesen la poblaci��n general, las personas fumadoras adictas al juego est��n representadas en lasdiferentes etapas de cambio con porcentajes parecidos a los de dicha poblaci��n. Por otra parte,no se ha encontrado relaci��n entre el nivel de dependencia medido con el Test de Fagerstr��m yla etapa de cambio. En cuanto a la influencia de las consecuencias percibidas del consumo detabaco, en general los sujetos tienden a conceder mayor importancia a los perjuicios que a losbeneficios de fumar. En los an��lisis en funci��n de las etapas de cambio, se encuentran diferenciassignificativas entre el grupo de los que piensan dejar de fumar en los pr��ximos seis meses,(contempladores y preparados) y el grupo de los que no fuman (exfumadores y no fumadores) enel beneficio ���fumar ayuda a relajarse��� que es m��s valorado por los primeros. Tambi��n seencuentran dichas diferencias entre los precontempladores y los que no fuman en dos perjuicios:���fumar produce a veces dolor de cabeza��� y ���fumar a veces provoca taquicardia��� que son m��svalorados por los segundos. Estos resultados sugieren la conveniencia de realizar las intervencionesm��s adecuadas para cada etapa de cambio, a fin de que las personas adictas al juegopuedan tambi��n tener ��xito en el abandono de la adicci��n al tabaco

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.

Executive functions profile in extreme eating/weight conditions: from anorexia nervosa to obesity.

BACKGROUND Extreme weight conditions (EWC) groups along a continuum may share some biological risk factors and intermediate neurocognitive phenotypes. A core cognitive trait in EWC appears to be executive dysfunction, with a focus on decision making, response inhibition and cognitive flexibility. Differences between individuals in these areas are likely to contribute to the differences in vulnerability to EWC. The aim of the study was to investigate whether there is a common pattern of executive dysfunction in EWC while comparing anorexia nervosa patients (AN), obese subjects (OB) and healthy eating/weight controls (HC). METHODS Thirty five AN patients, fifty two OB and one hundred thirty seven HC were compared using the Wisconsin Card Sorting Test (WCST); Stroop Color and Word Test (SCWT); and Iowa Gambling Task (IGT). All participants were female, aged between 18 and 60 years. RESULTS There was a significant difference in IGT score (F(1.79); p<.001), with AN and OB groups showing the poorest performance compared to HC. On the WCST, AN and OB made significantly more errors than controls (F(25.73); p<.001), and had significantly fewer correct responses (F(2.71); p<.001). Post hoc analysis revealed that the two clinical groups were not significantly different from each other. Finally, OB showed a significant reduced performance in the inhibition response measured with the Stroop test (F(5.11); p<.001) compared with both AN and HC. CONCLUSIONS These findings suggest that EWC subjects (namely AN and OB) have similar dysfunctional executive profile that may play a role in the development and maintenance of such disorders.

Modulation of the Endocannabinoids N-Arachidonoylethanolamine (AEA) and 2-Arachidonoylglycerol (2-AG) on Executive Functions in Humans.

Animal studies point to an implication of the endocannabinoid system on executive functions. In humans, several studies have suggested an association between acute or chronic use of exogenous cannabinoids (��9-tetrahydrocannabinol) and executive impairments. However, to date, no published reports establish the relationship between endocannabinoids, as biomarkers of the cannabinoid neurotransmission system, and executive functioning in humans. The aim of the present study was to explore the association between circulating levels of plasma endocannabinoids N-arachidonoylethanolamine (AEA) and 2-Arachidonoylglycerol (2-AG) and executive functions (decision making, response inhibition and cognitive flexibility) in healthy subjects. One hundred and fifty seven subjects were included and assessed with the Wisconsin Card Sorting Test; Stroop Color and Word Test; and Iowa Gambling Task. All participants were female, aged between 18 and 60 years and spoke Spanish as their first language. Results showed a negative correlation between 2-AG and cognitive flexibility performance (r���=���-.37; p<.05). A positive correlation was found between AEA concentrations and both cognitive flexibility (r���=���.59; p<.05) and decision making performance (r���=���.23; P<.05). There was no significant correlation between either 2-AG (r���=���-.17) or AEA (r���=���-.08) concentrations and inhibition response. These results show, in humans, a relevant modulation of the endocannabinoid system on prefrontal-dependent cognitive functioning. The present study might have significant implications for the underlying executive alterations described in some psychiatric disorders currently associated with endocannabinoids deregulation (namely drug abuse/dependence, depression, obesity and eating disorders). Understanding the neurobiology of their dysexecutive profile might certainly contribute to the development of new treatments and pharmacological approaches.

Progressive decline of decision-making performances during multiple sclerosis.

The purpose of this study was to evaluate longitudinally, using the Iowa Gambling Task (IGT), the dynamics of decision-making capacity at a two-year interval (median: 2.1 years) in a group of patients with multiple sclerosis (MS) (n = 70) and minor neurological disability [Expanded Disability Status Scale (EDSS) &lt; or = 2.5 at baseline]. Cognition (memory, executive functions, attention), behavior, handicap, and perceived health status were also investigated. Standardized change scores [(score at retest-score at baseline)/standard deviation of baseline score] were computed. Results showed that IGT performances decreased from baseline to retest (from 0.3, SD = 0.4 to 0.1, SD = 0.3, p = .005). MS patients who worsened in the IGT were more likely to show a decreased perceived health status and emotional well-being (SEP-59; p = .05 for both). Relapsing rate, disability progression, cognitive, and behavioral changes were not associated with decreased IGT performances. In conclusion, decline in decision making can appear as an isolated deficit in MS.

Modulation of Higher-Order Olfaction Components on Executive Functions in Humans.

The prefrontal (PFC) and orbitofrontal cortex (OFC) appear to be associated with both executive functions and olfaction. However, there is little data relating olfactory processing and executive functions in humans. The present study aimed at exploring the role of olfaction on executive functioning, making a distinction between primary and more cognitive aspects of olfaction. Three executive tasks of similar difficulty were used. One was used to assess hot executive functions (Iowa Gambling Task-IGT), and two as a measure of cold executive functioning (Stroop Colour and Word Test-SCWT and Wisconsin Card Sorting Test-WCST). Sixty two healthy participants were included: 31 with normosmia and 31 with hyposmia. Olfactory abilities were assessed using the ''Sniffin' Sticks'' test and the olfactory threshold, odour discrimination and odour identification measures were obtained. All participants were female, aged between 18 and 60. Results showed that participants with hyposmia displayed worse performance in decision making (IGT; Cohen's-d = 0.91) and cognitive flexibility (WCST; Cohen's-d between 0.54 and 0.68) compared to those with normosmia. Multiple regression adjusted by the covariates participants' age and education level showed a positive association between odour identification and the cognitive inhibition response (SCWT-interference; Beta = 0.29; p = .034). The odour discrimination capacity was not a predictor of the cognitive executive performance. Our results suggest that both hot and cold executive functions seem to be associated with higher-order olfactory functioning in humans. These results robustly support the hypothesis that olfaction and executive measures have a common neural substrate in PFC and OFC, and suggest that olfaction might be a reliable cognitive marker in psychiatric and neurologic disorders.

VIP Connection Newsletter, August 2004, Vol. 4, no 3.

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