Deductive and inductive reasoning in Parkinson's disease patients and normal controls: review and experimental evidence

Verbal Reasoning Impairment in Parkinson’s Disease

Background. The aim of this study was to assess verbal reasoning (VR) functioning in patients with Parkinson’s disease (PD) and healthy controls (HCs). Methods. The non-demented PD patients and HCs matched by age and global cognition were enrolled in this study. VR was assessed with the verbal reasoning test (VRT), total score, and subsets. Results. Eighty-seven PD patients (51 men; mean age $63.8\pm 7.9$ years) and 87 HCs (46 men; mean age $63.7\pm 8.0$ years) were enrolled. At univariate analysis, PD patients presented a significantly lower score in the VRT subset classification ( $12.3\pm 2.1$ ) than HCs ( $12.9\pm 1.7$ ) with an odds ratio (OR) of 0.8 (95% confidence interval [CI] 0.70–0.98; $p=0.003$ ). The strength of association was also confirmed at multivariate analysis (OR = 0.8, 95% CI 0.70–0.98; $p=0.003$ ). Moreover, in PD patients, a statistically significant positive correlation was found between VRT-classification and MoCA scores ( $r=0.330$ ; $p=0.002$ ). Conclusions. PD patients presented lower VR performance than HCs.

Enhanced creative thinking under dopaminergic therapy in Parkinson disease

OBJECTIVE

Creative thinking requires a combination of originality, flexibility, and usefulness. Several reports described enhanced artistic creativity in Parkinson disease (PD) patients treated with dopaminergic agents. We aimed to examine PD patients' ability to perform creativity tasks compared to healthy controls and to verify whether creativity is related to an impulse control disorder (ICD) as a complication of dopaminergic therapy.

METHODS

Right-handed PD patients treated with dopamine agonists and/or levodopa, and age- and education- matched neurologically healthy controls were assessed using the Montreal Cognitive Assessment, semantic verbal fluency, Beck Depression Inventory, and Questionnaire for Impulsive-Compulsive Disorders in Parkinson Disease Rating Scale (QUIP-RS). Creativity assessment included Comprehension of Novel Metaphors (CNM), Remote Association Test, and Tel Aviv Creativity Test (TACT). Groups were compared using analyses of variance, t tests, and correlation analyses.

RESULTS

Twenty-seven PD patients (age, mean ± standard deviation = 62 ± 7 years; education = 16 ± 3 years; disease duration = 5.8 ± 3.9 years) and 27 controls (age = 59 ± 9 years; education 17 ± 3 years) participated. PD patients performed significantly better than controls in divergent thinking tasks; specifically, the TACT-Visual for both fluency (33.48 ± 11.83 vs 25.59 ± 10.27, p = 0.034) and quality (15.78 ± 7.6 vs 11.19 ± 6.22, p = 0.025). Comprehension of Novel Metaphors was better in PD patients vs controls (0.71 ± 0.23 vs 0.55 ± 0.29, p = 0.04). QUIP-RS scores did not correlate with creativity measures.

INTERPRETATION

PD patients treated with dopaminergic drugs demonstrated enhanced verbal and visual creativity as compared to neurologically healthy controls. This feature was unrelated to ICD. Dopaminergic agents might act through the reduction of latent inhibition, resulting in widening of the associative network and enriched divergent thinking.

Longitudinal Differences in Cognitive Functioning Among Older Adults With and Without Heart Failure

Objective: Secondary data analyses were conducted to examine cognitive function and longitudinal cognitive decline among older adults with and without heart failure (HF). Method: Data from the Advanced Cognitive Training for Independent and Vital Elderly study were used to compare baseline ( N = 2,790) and longitudinal ( n = 692) changes in memory, reasoning, and speed of processing performance among participants ( M age = 73.61, SD = 5.89) who self-reported HF at baseline, developed HF over time, or never reported HF. Results: At baseline, there were differences in memory and speed of processing with participants who never reported HF performing better than those who reported developing HF over time, and those who reported HF at baseline performing the worst ( ps < .05). Longitudinally, participants with self-reported HF at baseline showed declines in reasoning over time. Discussion: The results indicate that cognitive difficulties in memory and speed may occur prior to a HF diagnosis, while those with HF may experience steeper declines in reasoning as measured by word series test.

The significance of neuronal lateralisation in Parkinson's disease

The destruction of the dopaminergic neurons in the substantia nigra (SN) and consequent depletion of striatal dopamine elicits the main movement deficits related to Parkinson's disease (PD). In the early stages of the illness, the motor symptoms are often exhibited asymmetrically. Thus, the onset of PD features starts on either the right or left side. The side of onset appears to determine the prognosis of the disorder and other features, such as right-side tremor dominance has a better prognosis in contrast to left-side dominant bradykinesia-rigidity. In addition, left-side onset of motor features is associated with cognitive decline. Therefore, an intricate relation appears to exist between the side of disease onset and progression/severity and other non-motor symptoms. Unilateral PD in turn corresponds to neuronal nigrostriatal degeneration in the contralateral hemisphere. Indeed positron emission tomography has demonstrated a positive correlation between symptom asymmetry and brain function (Hoorn et al. Parkinsonism Relat Disord 17:58-60, 2011), which corresponds to a unilateral pattern of degeneration. This phenomenon appears to be exclusive to PD. Additionally, the variation in motor symptom(s) dominance exhibited in the disorder conforms to the notion that PD is a spectrum disease with many sub-groups. Thus, clinical and post mortem studies on "lateralisation" may serve as a vital tool in understanding the mechanism(s) eliciting the characteristic destruction of the SN neurons. Additionally, it may be employed as a predictive indicator for the symptomology and prognosis of the illness thus allowing selective treatment strategies targeted at the pronounced hemispheric degeneration.

Everyday reasoning abilities in persons with Parkinson's disease

Parkinson's disease (PD) patients develop progressive cognitive decline. The degree to which such decline impacts instrumental activities of daily living (IADL) among individuals in the early stages of PD without dementia is not well documented. The Everyday Cognitive Battery Reasoning subtest (ECB) was used to assess ability to solve everyday reasoning tasks for IADL among 19 non-demented older adults with PD in comparison to 20 older adults without PD. The two groups were similar in age, education, race and gender. Individuals with PD had significantly lower scores (M = 61.98, SD = 12.03) than the comparison group (M = 69.80, SD = 9.48). Individuals with PD, who do not have dementia, may be more likely to experience difficulties in IADL requiring reasoning including medication use, finances, and nutrition. Even more serious implications lie in the capacity to make treatment choices.

Effects of verbal working memory deficits on metaphor comprehension in patients with Parkinson's disease

This research studied one aspect of pragmatic language processing, the ability to understand metaphorical language, to determine whether patients with Parkinson disease (PD) are impaired for these abilities, and whether cognitive resource limitations/fronto-striatal dysfunction contributes to these deficits. Seventeen PD participants and healthy controls (HC) completed a series of neuropsychological tests and performed a metaphor comprehension task following the methods of Gernsbacher and colleagues [Gernsbacher, M. A., Keysar, B., Robertson, R. R. W., & Werner, N. K. (2001). The role of suppression and enhancement in understanding metaphors. Journal of Memory and Language, 45, 433-450.] When participants in the PD group were identified as "impaired" or "unimpaired" relative to the control group on a measure of verbal working memory span, we found that only PD participants with impaired working memory were simultaneously impaired in the processing of metaphorical language. Based on our findings we argue that certain "complex" forms of language processing such as metaphor interpretation are highly dependent on intact fronto-striatal systems for working memory which are frequently, although not always, compromised during the early course of PD.

Is theory-of-mind impaired in Parkinson's disease?

INTRODUCTION

Theory-of-mind (ToM) refers to the ability to understand and predict the behaviour of others based on their mental states. Research from brain imaging and lesion studies indicate that the frontal lobes are both involved and necessary to understand mental states.

METHODS

A total of 13 people with Parkinson's disease were compared with 11 age-matched controls on tasks involving ToM, based on the hypothesis that the frontal lobes are affected by Parkinson's disease. The four tasks included both ToM and non-ToM components, such as memory, to investigate the specific nature of the deficit.

RESULTS

The group with Parkinson's disease scored significantly lower on three out of four of the ToM components of the tasks, relative to controls, but were not impaired on any of the non-ToM components of the four tasks.

CONCLUSION

The results suggest the impairment was specific to ToM and thus have implications for a dedicated specific ToM module.