Evidence indicates that dopaminergic medication in Parkinson's disease may impair certain aspects of cognitive function, such as reversal learning. We used functional magnetic resonance imaging in ...patients with mild Parkinson's disease to investigate the neural site at which L-DOPA acts during reversal learning. Patients were scanned both ON and OFF their normal dopamine-enhancing L-DOPA medication during the performance of a probabilistic reversal learning task. We demonstrate that L-DOPA modulated reversal-related activity in the nucleus accumbens, but not in the dorsal striatum or the prefrontal cortex. These data concur with evidence from studies with experimental animals and indicate an important role for the human nucleus accumbens in the dopaminergic modulation of reversal learning.
Homelessness and problem gambling are two public health concerns in the UK that are rarely considered concurrently, and little is known about the extent of gambling involvement and problematic ...gambling in the homeless. We recruited 456 individuals attending homelessness services in London, UK. All participants completed a screen for gambling involvement, and where gambling involvement was endorsed, the Problem Gambling Severity Index (PGSI) was administered. The PGSI risk categories were compared against data from the 2010 British Gambling Prevalence Survey (BGPS). PGSI problem gambling was indicated in 11.6 % of the homeless population, compared to 0.7 % in the BGPS. Of participants endorsing any PGSI symptoms, a higher proportion of homeless participants were problem gamblers relative to the low and moderate risk groups, compared to the BGPS data. These results confirm that the homeless constitute a vulnerable population for problem gambling, and that diagnostic tools for gambling involvement should be integrated into homelessness services in the UK.
Recovery in bipolar disorder is central to its definition but is rarely complete. Previous work has suggested that neuropsychological impairment persists during the euthymic state but has been ...confounded partly by mild affective symptoms in remitted patients.
To characterise neuropsychological functioning in the euthymic phase of bipolar disorder with an emphasis on tasks of executive functioning.
Thirty euthymic patients with bipolar disorder were compared with thirty healthy controls on neuropsychological tasks differentially sensitive to damage within prefrontal cortex.
Bipolar I patients were impaired on tasks of attentional set shifting, verbal memory and sustained attention. Only sustained attention deficit survived controlling for mild affective symptoms. This deficit was related to progression of illness, but was none the less present in a subgroup of patients near illness onset.
Sustained attention deficit may represent a neuropsychological vulnerability marker for bipolar disorder, providing a focus for further understanding of the phenotype and analysis of the neuronal networks involved.
Event-related functional magnetic resonance imaging was used to measure blood oxygenation level-dependent responses in 16 young healthy human volunteers during performance of an attentional switching ...task. The task allowed the separate investigation of lower-order switching between concrete objects and higher-order switching between abstract task rules. Significant signal change in the ventral striatum was demonstrated on trials when subjects switched between objects but not when subjects switched between abstract task rules. In contrast, signal change in the lateral prefrontal cortex (PFC) was observed during all switch trials. The switch-related responses were not contaminated by task difficulty, because the greatest signal change was observed during the relatively easy switch trials, which required both lower-order and higher-order switching at the same time. The present data suggest that mechanisms of inhibitory response control in frontostriatal systems are organized according to distinct levels of abstraction. Specifically, the response selection computation carried by the ventral striatum, which projects to the orbitofrontal cortex and the medial PFC, is restricted to the transformation of concrete stimulus exemplar information into motor responses, whereas the adaptive function of the lateral PFC extends to the transformation of abstract task-rule representations into action.
•People often use justifications to make desirable choices, but is this related to gambling problems?•Justifications are associated with problem gambling beyond gambling cognitions and ...impulsivity.•Justifications are positively correlated with urgency and gambling cognitions.•The use of justifications may represent a neglected aspect of gambling cognitions.
People often use justifications to make desirable choices, but little is known about these justificatory thoughts in gambling. We conducted an exploratory Study 1 (n = 101) and a confirmatory Study 2 (n = 154) using online surveys, recruiting gamblers with prior and current experience of trying to reduce their gambling. Using justifications recognized in the domains of eating and consumer behavior (e.g., prior use of effort, feelings of achievement), we examined whether justifications were associated with problem gambling severity, and whether they explained additional variance above trait impulsivity and cognitive distortions. In both studies, justifications were positively associated with problem gambling severity, after accounting for trait impulsivity and cognitive distortions. Additionally, justifications were positively correlated with trait urgency and cognitive distortions, indicating that such thinking may not be antithetical to impulsivity. These data provide proof-of-principle evidence that justificatory thinking occurs in the context of gambling, is related to problem gambling severity, and may therefore represent a neglected aspect of gambling-related cognitions.
Event-related functional magnetic resonance imaging was used to measure blood oxygenation level-dependent responses in 13 young healthy human volunteers during performance of a probabilistic ...reversal-learning task. The task allowed the separate investigation of the relearning of stimulus-reward associations and the reception of negative feedback. Significant signal change in the right ventrolateral prefrontal cortex was demonstrated on trials when subjects stopped responding to the previously relevant stimulus and shifted responding to the newly relevant stimulus. Significant signal change in the region of the ventral striatum was also observed on such reversal errors, from a region of interest analysis. The ventrolateral prefrontal cortex and ventral striatum were not significantly activated by the other, preceding reversal errors, or when subjects received negative feedback for correct responses. Moreover, the response on the final reversal error, before shifting, was not modulated by the number of preceding reversal errors, indicating that error-related activity does not simply accumulate in this network. The signal change in this ventral frontostriatal circuit is therefore associated with reversal learning and is uncontaminated by negative feedback. Overall, these data concur with findings in rodents and nonhuman primates of reversal-learning deficits after damage to ventral frontostriatal circuitry, and also support recent clinical findings using this task.
•Variability of reward may ensure ongoing activation of midbrain dopamine neurons.•Such variability may confer ‘drug-like’ addictive potential to non-drug rewards.•Internet-based gambling, ...videogames, shopping and pornography fit this profile.•Coupled with high frequency delivery, this may promote sensitization and behavioural addiction.
Influential learning-based accounts of substance addictions posit the attribution of incentive salience to drug-associated cues, and its escalation by the direct dopaminergic effects of drugs. In translating this account to disordered gambling, we have noted how the intermittent nature of monetary rewards in gambling (i.e. the variable ratio) may allow for analogous learning processes, via effects on dopaminergic signalling. The aim of the present article is to consider how multiple sources of reward variability operate within modern gambling products, and how similar sources of variability, as well as some novel sources of variability, also apply to other digital products implicated in behavioural addictions, including gaming, shopping, social media and online pornography. Online access to these activities facilitates not only unparalleled accessibility but also introduces novel forms of reward variability, as seen in the effects of infinite scrolls and personalized recommendations. We use the term uncertainty to refer to the subjective experience of reward variability. We further highlight two psychological factors that appear to moderate the effects of uncertainty: 1) the timecourse of uncertainty, especially with regard to its resolution, 2) the frequency of exposure, allowing temporal compression. Collectively, the evidence illustrates how qualitative and quantitative variability of reward can confer addictive potential to non-drug reinforcers by exploiting the psychological and neural processes that rely on predictability to guide reward seeking behaviour.
Deficits in executive functions may play an important role in late-life suicide; however the association is understudied. This study examined cognitive function in general and executive functioning ...specifically in depressed elderly with and without suicidal ideation and attempts.
Case-control study.
University-affiliated psychiatric hospital.
We compared 32 suicidal depressed participants aged 60 and older with 32 non-suicidal depressed participants equated for age, education, and gender.
We assessed global cognitive function and executive function with the Dementia Rating Scale (DRS) and the Executive Interview (EXIT25), respectively.
Suicidal and non-suicidal depressed groups were comparable in terms of severity of depression and burden of physical illness. Suicidal participants performed worse on the EXIT25, and on the DRS total scale, as well as on Memory and Attention subscales. The differences were not explained by the presence of dementia, substance use, medication exposure, or brain injury from suicide attempts.
Poor performance on tests of executive function, attention, and memory is associated with suicidal behavior in late-life depression.
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