Matthias Brand

Decisions under ambiguity and decisions under risk: correlations with executive functions and comparisons of two different gambling tasks with implicit and explicit rules

We conducted two experiments with healthy subjects to investigate the possible relationships between Iowa Gambling Task (IGT) performance and executive functions as well as IGT performance and decision-making in a task with explicit rules, the Game of Dice Task (GDT). Results indicated that only the last trials of the IGT were correlated with executive functions and GDT performance. We suggest that the IGT taps into two mechanisms of decision-making: decisions under ambiguity in the first trials and decisions under risk in the latter trials. Results have impact on the interpretation of deficient IGT performance in patients with frontal lobe dysfunctions.

Neuropsychological correlates of decision-making in ambiguous and risky situations

Decision-making situations in real life differ regarding their explicitness of positive and negative consequences as well as regarding the directness of probabilities for reward and punishment. In neuropsychological research, decisions under ambiguity and decisions under risk are differentiated. To assess decisions under ambiguity the Iowa Gambling Task (IGT) is one of the most frequently used tasks. Decisions under risk can be measured by a task that offers explicit rules for gains and losses and stable winning probabilities, as the Game of Dice Task (GDT) does. In this contribution we firstly summarize studies that investigated decision-making in various groups of patients using the IGT or the GDT. We also propose a new model of decision-making in risky situations and describe differences between decisions under ambiguity and decisions under risk from a theoretical and clinical perspective.

Decision-Making Deficits of Korsakoff Patients in a New Gambling Task With Explicit Rules: Associations With Executive Functions.

Decision-making deficits reflected by risky decisions in gambling tasks have been associated with frontal lobe dysfunctions in various neurologic and psychiatric populations. The question remains whether decision-making impairments are related to executive functions. The authors developed a new gambling task, the Game of Dice Task, with explicit and stable rules for reinforcement and punishment, to investigate relations between executive functions and risk-taking behavior in an explicit decision-making situation. A sample of 35 alcoholic Korsakoff patients and 35 healthy controls was examined with the Game of Dice Task and a neuropsychological test battery. Results show that Korsakoff patients are strongly impaired in this explicit decision-making task and that these disturbances are correlated with specific executive functions.

Decision making under stress: a selective review.

Many decisions must be made under stress, and many decision situations elicit stress responses themselves. Thus, stress and decision making are intricately connected, not only on the behavioral level, but also on the neural level, i.e., the brain regions that underlie intact decision making are regions that are sensitive to stress-induced changes. The purpose of this review is to summarize the findings from studies that investigated the impact of stress on decision making. The review includes those studies that examined decision making under stress in humans and were published between 1985 and October 2011. The reviewed studies were found using PubMed and PsycInfo searches. The review focuses on studies that have examined the influence of acutely induced laboratory stress on decision making and that measured both decision-making performance and stress responses. Additionally, some studies that investigated decision making under naturally occurring stress levels and decision-making abilities in patients who suffer from stress-related disorders are described. The results from the studies that were included in the review support the assumption that stress affects decision making. If stress confers an advantage or disadvantage in terms of outcome depends on the specific task or situation. The results also emphasize the role of mediating and moderating variables. The results are discussed with respect to underlying psychological and neural mechanisms, implications for everyday decision making and future research directions.

Decision-making impairments in patients with pathological gambling

Pathological gambling (PG) is most likely associated with functional brain changes as well as neuropsychological and personality alterations. Recent research with the Iowa Gambling Task suggests decision-making impairments in PG. These deficits are usually attributed to disturbances in feedback processing and associated functional alterations of the orbitofrontal cortex. However, previous studies with other clinical populations found relations between executive (dorsolateral prefrontal) functions and decision-making using a task with explicit rules for gains and losses, the Game of Dice Task. In the present study, we assessed 25 male PG patients and 25 male healthy controls with the Game of Dice Task. PG patients showed pronounced deficits in the Game of Dice Task, and the frequency of risky decisions was correlated with executive functions and feedback processing. Therefore, risky decisions of PG patients might be influenced by both dorsolateral prefrontal and orbitofrontal cortex dysfunctions.

Decision-making impairments in patients with Parkinson's disease

A high percentage of Parkinson’s disease (PD) patients show cognitive impairments in addition to the cardinal motor symptoms. These deficits primarily concern executive functions most probably linked to dysfunctions in prefrontal regions due to decreased dopaminergic transmission in fronto-striatal loops. To investigate possible associations between decision-making and executive functions in PD, we examined 20 non-demented PD patients and 20 healthy control subjects with a neuropsychological test battery and the Game of Dice Task. In this computerised decision-making task, the rules for gains and losses and the winning probabilities are obvious and stable. Thus, strategic components besides feedback processing might influence decision-making in this task. We found that PD patients were impaired in the Game of Dice task performance and that the frequency of disadvantageous choices correlated with both executive functions and feedback processing. We suggest that decision-making deficits of PD patients in explicit gambling situations might be associated with dysfunctions in two different fronto-striatal loops: the limbic-orbitofrontal-striatal loop, involved in feedback processing, and the dorsolateral prefrontal-striatal loop, involved in executive functions.

Role of the amygdala in decisions under ambiguity and decisions under risk: evidence from patients with Urbach-Wiethe disease.

Various neuropsychological studies have shown that decision-making deficits can occur in a wide range of patients with brain damage or dysfunctions. Decisions under ambiguity, as measured with the Iowa Gambling Task, primarily depend on the integrity of the ventromedial prefrontal cortex and the amygdala, as well as on further brain regions such as the somatosensory cortex. However, little is known about the specific role of these structures in decisions under risk measured with tasks that offer explicit rules for gains and losses and winning probabilities, for example, the Game of Dice Task. We aimed to investigate the potential role of the amygdala for decisions under risk. For this purpose, we examined three patients with Urbach-Wiethe disease--a rare syndrome associated with selective bilateral mineralisation of the amygdalae. Neuropsychological performance was assessed with the Iowa Gambling Task (decisions under ambiguity), the Game of Dice Task (decisions under risk), and an extensive neuropsychological test battery focussing on executive functions. Furthermore, previous studies found relationships between generating skin conductance responses and deciding advantageously in the Iowa Gambling Task. Accordingly, we recorded skin conductance responses during both decision tasks as a measure of emotional reactivity. Results indicate that patients with selective amygdala damage have lower scores in both decisions under ambiguity and decisions under risk. Decisions under risk are especially compromised in patients who also demonstrate deficits in executive functioning. In both gambling tasks, patients showed reduced skin conductance responses compared to healthy comparison subjects. The results suggest that deciding advantageously under risk conditions involves both the use of feedback from previous trials, as required by decisions under ambiguity, and in addition, executive functions.

Prefrontal control and Internet addiction: a theoretical model and review of neuropsychological and neuroimaging findings

Most people use the Internet as a functional tool to perform their personal goals in everyday-life such as making airline or hotel reservations. However, some individuals suffer from a loss of control over their Internet use resulting in personal distress, symptoms of psychological dependence, and diverse negative consequences. This phenomenon is often referred to as Internet addiction. Only Internet Gaming Disorder has been included in the appendix of the DSM-5, but it has already been argued that Internet addiction could also comprise problematic use of other applications with cybersex, online relations, shopping, and information search being Internet facets at risk for developing an addictive behavior. Neuropsychological investigations have pointed out that certain prefrontal functions in particular executive control functions are related to symptoms of Internet addiction, which is in line with recent theoretical models on the development and maintenance of the addictive use of the Internet. Control processes are particularly reduced when individuals with Internet addiction are confronted with Internet-related cues representing their first choice use. For example, processing Internet-related cues interferes with working memory performance and decision making. Consistent with this, results from functional neuroimaging and other neuropsychological studies demonstrate that cue-reactivity, craving, and decision making are important concepts for understanding Internet addiction. The findings on reductions in executive control are consistent with other behavioral addictions, such as pathological gambling. They also emphasize the classification of the phenomenon as an addiction, because there are also several similarities with findings in substance dependency. The neuropsychological and neuroimaging results have important clinical impact, as one therapy goal should enhance control over the Internet use by modifying specific cognitions and Internet use expectancies.

Anticipatory stress influences decision making under explicit risk conditions.

Recent research has suggested that stress may affect memory, executive functioning, and decision making on the basis of emotional feedback processing. The current study examined whether anticipatory stress affects decision making measured with the Game of Dice Task (GDT), a decision-making task with explicit and stable rules that taps both executive functioning and feedback learning. The authors induced stress in 20 participants by having them anticipate giving a public speech and also examined 20 comparison subjects. The authors assessed the level of stress with questionnaires and endocrine markers (salivary cortisol and alpha-amylase), both revealing that speech anticipation led to increased stress. Results of the GDT showed that participants under stress scored significantly lower than the comparison group and that GDT performance was negatively correlated with the increase of cortisol. Our results indicate that stress can lead to disadvantageous decision making even when explicit and stable information about outcome contingencies is provided.

Anosognosia in Very Mild Alzheimer’s Disease but Not in Mild Cognitive Impairment

Objective: To study awareness of cognitive dysfunction in patients with very mild Alzheimer’s disease (AD) and subjects with mild cognitive impairment (MCI). Methods: A complaint interview covering 13 cognitive domains was administered to 82 AD and 79 MCI patients and their caregivers. The patient groups were comparable according to age and education, and Mini Mental State Examination (MMSE) scores were ≧24 in all cases. The discrepancy between the patients’ and caregivers’ estimations of impairments was taken as a measure of anosognosia. Results: Self-reports of cognitive difficulties were comparable for AD and MCI patients. However, while in comparison to caregivers MCI patients reported significantly more cognitive impairment (p < 0.05), AD patients complained significantly less cognitive dysfunctions (p < 0.001). Conclusions: While most MCI patients tend to overestimate cognitive deficits when compared to their caregiver’s assessment, AD patients in early stages of disease underestimate cognitive dysfunctions. Anosognosia can thus be regarded as a characteristic symptom at a stage of very mild AD (MMSE ≧24) but not MCI. Accordingly, medical history even in mildly affected patients should always include information from both patient and caregiver.