Janneke Koerts

The impact of executive functions on verb production in patients with Parkinson's disease

A growing number of studies suggest that language problems in Parkinsons disease (PD) are a result of executive dysfunction. To test this hypothesis we compared Dutch verb production in sentence context in a group of 28 PD patients with a control group consisting of 28 healthy participants matched for age, gender and education. All subjects were assessed on both verb production in sentence context as well as on cognitive functions relevant for sentence processing. PD patients scored lower than healthy controls on the verb production ability-scale and showed a response pattern in which performance was worse (1) in base than in derived position; (2) in present than in past tense; (3) for intransitive than in transitive verbs. For the PD group the score on the verb production ability-scale correlated significantly with set-switching and working memory. These results provide support for previous research suggesting that executive dysfunctions underlie the performance of the PD patients on verb production. It is furthermore suggested that because of failing automaticity, PD patients rely more on the cortically represented executive functions. Unfortunately, due to the disturbed intimate relation between the basal ganglia and the frontal cortex, these executive functions are also dysfunctional.

Stigma in attention deficit hyperactivity disorder

Attention deficit hyperactivity disorder (ADHD) is a frequently diagnosed disorder in child- and adulthood with a high impact affecting multiple facets of social life. Therefore, patients suffering from ADHD are at high risk to be confronted with stigma, prejudices, and discrimination. A review of the empirical research in the field of ADHD with regard to stigma was performed. The findings of investigations in this field were clustered in different categories, including stigma in children with ADHD, stigma in adults with ADHD, stigma in relatives or in people close to a patient with ADHD, and the influence of stigma on authorities’ attitudes toward patients with ADHD. Variables identified to contribute to stigma in ADHD are public’s uncertainty concerning the reliability/validity of an ADHD diagnosis and the related diagnostic assessment, public’s perceived dangerousness of individuals with ADHD, socio-demographical factors as age, gender, and ethnicity of the respondent or the target individual with ADHD, stigmatization of ADHD treatment, for example public’s skepticism toward ADHD medication and disclosure of diagnostic status as well as medication status of the individual with ADHD. The contribution of stigma associated with ADHD can be conceptualized as an underestimated risk factor, affecting treatment adherence, treatment efficacy, symptom aggravation, life satisfaction, and mentally well-being of individuals affected by ADHD. Public as well as health professionals’ concepts about ADHD are highly diverse, setting individuals with an ADHD diagnosis at greater risk to get stigmatized.

Cognitive dysfunction in non-demented Parkinson's disease patients: Controlled and automatic behavior

The evidence with regard to impaired automatic and controlled information processing in non-demented patients with Parkinsons disease (PD) is critically discussed. We use a comprehensive mental schema framework of executive functioning, that is the planning and regulation of behavior in complex everyday tasks (International Classification of Functioning - ICF - activity level). In this framework monitoring, inhibition, mental effort, planning, working memory and flexibility are important elements of controlled processing (supervisory attentional control) and controlled processing can only influence performance by modulating automatic processes. The striatum plays an important role in the interface between controlled and automatic processes. It is wel documented that PD patients show impairments applying and achieving automaticities. With sustained cortical control of task performance during both automatic and controlled processing, not showing the transition to striatal control, which is normal in the case of skill learning. In addition, PD patients have been shown to be limited in executive functioning. Many authors have interpreted this as evidence for impaired executive functions (ICF body level). But the question must be asked to what extent these limitations are an indirect effect of impaired automatic processing. To answer this question, studies on executive functioning are critically assessed with regard to the control they have provided for impaired automaticity. It is concluded that only for cognitive flexibility and working memory, the evidence for impairments is convincing because significant limitations have also been shown in tasks with very low automatic processing demands. Impairments in other executive functions, such as monitoring, inhibition and planning have not been convincingly shown in non-demented PD patients and are likely to be due to treatment strategies and factors such as fatigue.

Visual Object Recognition and Attention in Parkinson's Disease Patients with Visual Hallucinations

Visual hallucinations (VH) are common in Parkinsons disease (PD) and are hypothesized to be due to impaired visual perception and attention deficits. We investigated whether PD patients with VH showed attention deficits, a more specific impairment of higher order visual perception, or both. Forty‐two volunteers participated in this study, including 14 PD patients with VH, 14 PD patients without VH and 14 healthy controls (HC), matched for age, gender, education level and for level of executive function. We created movies with images of animals, people, and objects dynamically appearing out of random noise. Time until recognition of the image was recorded. Sustained attention was tested using the Test of Attentional Performance. PD patients with VH recognized all images but were significantly slower in image recognition than both PD patients without VH and HC. PD patients with VH showed decreased sustained attention compared to PD patients without VH who again performed worse than HC. In conclusion, the recognition of objects is intact in PD patients with VH; however, these patients where significantly slower in image recognition than patients without VH and HC, which was not explained by executive dysfunction. Both image recognition speed and sustained attention decline in PD, in a more progressive way if VH start to occur.

Striatal dopaminergic activity (FDOPA-PET) associated with cognitive items of a depression scale (MADRS) in Parkinson's disease

Motor symptoms form the hallmark of Parkinsons disease (PD), although other features such as depression are often present. Currently‐used depression rating scales measure affective and somatic symptoms. These somatic symptoms of depression can also be core PD symptoms, suggesting an overlap of symptoms between depression and PD. Using in vivo radiotracer methods, striatal dopaminergic dysfunction is found in both PD and depression. This study investigates to what extent the overlapping symptoms of depression and PD are associated with the striatal dopaminergic dysfunction typical of PD. Symptoms of depression were assessed in 23 PD patients who did not have major depression according to the Montgomery–Åsberg depression rating scale (MADRS; cut‐off < 18) and according to a trained psychologist who interviewed all patients. The striatal dopaminergic activity of patients was assessed with FDOPA‐PET. Dopaminergic activity of the putamen and caudate nucleus was associated with MADRS total score and specifically with the symptom ‘Concentration difficulties’. These results suggest that the typical striatal dopaminergic dysfunction of PD can cause symptoms that can also be categorized as symptoms of depression. In particular, cognitive symptoms measured with a depression rating scale may be based on the dopaminergic dysfunction of the striatum in PD patients.

Cognitive functioning in patients treated for nonfunctioning pituitary macroadenoma and the effects of pituitary radiotherapy

Context and objective  Cognitive deterioration is reported in patients with a nonfunctioning pituitary macroadenoma (NFA) and after pituitary radiotherapy. However, reported results are inconsistent and are potentially confounded by different underlying pituitary disorders. The aim of this study was to examine cognitive functions in patients previously treated for NFA with or without radiotherapy.

Attentional and perceptual impairments in Parkinson's disease with visual hallucinations☆

Visual hallucinations (VH) are common in Parkinsons Disease (PD). Both deficits of perception and attention seem to play a role in the pathogenesis of VH in PD. However, the possible coexistence of impairments in attention and visual perception in PD with VH is not known. This study investigated both attention and visual perception in non-demented PD patients with VH, compared to PD patients without VH and healthy controls. Fourteen participants were included in each group. All patients were assessed with sustained visual attention and object and space perception tests. Only PD patients with VH showed impairments on object and space perception. In addition, PD patients with and without VH showed impairments on sustained visual attention, being more severely affected in PD patients with VH. Only in PD patients with VH sustained visual attention was associated with a decreased object and space perception. The results of our study thus suggest that in PD patients with VH an impairment of object and space perception, possibly in association with a decreased sustained visual attention, might play a role in the pathogenesis of VH.

Executive Functioning in Daily Life in Parkinson's Disease : Initiative, Planning and Multi-Task Performance

Impairments in executive functioning are frequently observed in Parkinsons disease (PD). However, executive functioning needed in daily life is difficult to measure. Considering this difficulty the Cognitive Effort Test (CET) was recently developed. In this multi-task test the goals are specified but participants are free in their approach. This study applies the CET in PD patients and investigates whether initiative, planning and multi-tasking are associated with aspects of executive functions and psychomotor speed. Thirty-six PD patients with a mild to moderate disease severity and thirty-four healthy participants were included in this study. PD patients planned and demonstrated more sequential task execution, which was associated with a decreased psychomotor speed. Furthermore, patients with a moderate PD planned to execute fewer tasks at the same time than patients with a mild PD. No differences were found between these groups for multi-tasking. In conclusion, PD patients planned and executed the tasks of the CET sequentially rather than in parallel presumably reflecting a compensation strategy for a decreased psychomotor speed. Furthermore, patients with moderate PD appeared to take their impairments into consideration when planning how to engage the tasks of the test. This compensation could not be detected in patients with mild PD.

Complex Prospective Memory in Adults with Attention Deficit Hyperactivity Disorder

Objectives Attention deficit hyperactivity disorder (ADHD) in adults has been associated with disturbances of attention and executive functions. Furthermore, impairments of verbal and figural retrospective memory were reported. However, little is known about the effects of ADHD on prospective memory, the execution of delayed intentions in the future. Methods The present study compared the performance of 45 adult patients with ADHD not treated with stimulant medication with the performance of 45 matched healthy individuals on a paradigm of complex prospective memory which measured task planning, plan recall, self-initiation and execution. Furthermore, the contribution of other cognitive functions to prospective memory functioning was assessed, including measures of attention, executive functions and memory. Results A large-scale impairment could be observed in task planning abilities in patients with ADHD. Only negligible to small effects were found for plan recall, self-initiation and execution. Inhibition was identified to contribute significantly to performance on task planning. Conclusions The present findings suggest that four cognitive components contribute to the performance of prospective memory. Impairments of prospective memory mainly emerged from deficient planning abilities in adults with ADHD. Implications on behavioral based intervention strategies are discussed.

Cognitive Impairment in Adult ADHD-Perspective Matters!

OBJECTIVE The assessment of cognitive functions of adults with attention deficit hyperactivity disorder (ADHD) comprises self-ratings of cognitive functioning (subjective assessment) as well as psychometric testing (objective neuropsychological assessment). The aim of the present study was to explore the utility of these assessment strategies in predicting neuropsychological impairments of adults with ADHD as determined by both approaches. METHOD Fifty-five adults with ADHD and 66 healthy participants were assessed with regard to cognitive functioning in several domains by employing subjective and objective measurement tools. Significance and effect sizes for differences between groups as well as the proportion of patients with impairments were analyzed. Furthermore, logistic regression analyses were carried out in order to explore the validity of subjective and objective cognitive measures in predicting cognitive impairments. RESULTS Both subjective and objective assessment tools revealed significant cognitive dysfunctions in adults with ADHD. The majority of patients displayed considerable impairments in all cognitive domains assessed. A comparison of effect sizes, however, showed larger dysfunctions in the subjective assessment than in the objective assessment. Furthermore, logistic regression models indicated that subjective cognitive complaints could not be predicted by objective measures of cognition and vice versa. CONCLUSIONS Subjective and objective assessment tools were found to be sensitive in revealing cognitive dysfunctions of adults with ADHD. Because of the weak association between subjective and objective measurements, it was concluded that subjective and objective measurements are both important for clinical practice but may provide distinct types of information and capture different aspects of functioning.