Abstract:
Assessing inhibitory control in early-stage Alzheimer's and Parkinson's disease using the Hayling Sentence Completion Test.

The ability to inhibit irrelevant information is essential for coping with the demands of everyday life. Inhibitory deficits are present in all stages of dementia and commonly observed in people with Parkinson's disease (PwPD). Inhibition is frequently tested with the Stroop test, but this may lack ecological validity. This study investigates inhibitory control in people with Alzheimer's disease dementia (PwD) and PwPD using the Hayling Sentence Completion Test (HSCT), which aspires to be a more ecologically valid task. A total of 117 people completed the HSCT, a test where participants have to complete a sentence with an unrelated word. The sample comprised 30 PwD, 33 PwPD, and 54 healthy older controls. We compared response times and the number and type of errors across the three groups. Completion time in Part B (Inhibition) did not distinguish between PwD, PwPD, and controls when controlling for the initiation speed, but a higher proportion of Category a errors (producing a word that fits the sentence when instructed otherwise) was a unique characteristic of inferior performance in PwD and PwPD. While not part of the standard test scoring protocol, controlling for the initiation speed and distinguishing between speed and accuracy in test performance appear to be essential for accurate evaluation of the inhibitory control in HSCT in older people. The findings suggest that the HSCT may be sensitive to verbal suppression deficits and may provide insight into inhibitory control in PwD and PwPD.

Abstract:
Individual goal-oriented cognitive rehabilitation to improve everyday functioning for people with early-stage dementia: a multicentre randomised controlled trial (the GREAT trial).

OBJECTIVES: to determine whether individual goal-oriented cognitive rehabilitation (CR) improves everyday functioning for people with mild-to-moderate dementia. DESIGN AND METHODS: Parallel group multicentre single-blind randomised controlled trial (RCT) comparing CR added to usual treatment (CR) with usual treatment alone (TAU) for people with an ICD-10 diagnosis of Alzheimer, vascular or mixed dementia, and mild-to-moderate cognitive impairment (Mini-Mental State Examination [MMSE] score ≥ 18), and with a family member willing to contribute. Participants allocated to CR received 10 weekly sessions over 3 months and four maintenance sessions over 6 months. Participants were followed up 3 and 9 months post randomisation by blinded researchers. The primary outcome was self-reported goal attainment at 3 months. Secondary outcomes at 3 and 9 months included informant-reported goal attainment, quality of life, mood, self-efficacy, and cognition and study partner stress and quality of life. RESULTS: We randomised (1:1) 475 people with dementia; 445 (CR = 281) were included in the intention to treat analysis at 3 months and 426 (CR = 208) at 9 months. At 3 months, there were statistically significant large positive effects for participant-rated goal attainment (d = 0.97; 95% CI, 0.75-1.19), corroborated by informant ratings (d = 1.11; 95% CI, 0.89-1.34). These effects were maintained at 9 months for both participant (d = 0.94; 95% CI, 0.71-1.17) and informant (d = 0.96; 95% CI, 0.73-1.2) ratings. The observed gains related to goals directly targeted in the therapy. There were no significant differences in secondary outcomes. CONCLUSIONS: CR enables people with early-stage dementia to improve their everyday functioning in relation to individual goals targeted in the therapy.

Abstract:
Quality of life, health status and caregiver burden in Parkinson's disease: relationship to executive functioning.

OBJECTIVE: High-quality person-centred care for people with Parkinson's disease (PwPD) and their families relies on identifying and addressing factors that specifically impact on quality of life (QoL). Deficits in executive functions (EF) are common in Parkinson's disease, but their impact on PwPD and their caregivers is not well understood. The present study evaluated how EF contributes to QoL and health status for the PwPD and caregiver burden. METHODS: Sixty-five PwPD completed measures of QoL, health status and EF, and 50 caregivers rated the EF of the PwPD and their own burden. Multiple regression analyses examined predictors of QoL (general life, health and movement disorders domains), health status and caregiver burden. RESULTS: Quality of life in the health and movement disorders domains was best explained by caregiver-rated EF, whereas QoL in the general life domain was best explained by level of depression. Health status was predicted by self-rated EF, with an objective EF measure also included in the regression model. Caregiver burden was best explained by caregiver-rated EF and disease severity, with general cognition and other factors also included in the regression model. CONCLUSIONS: Executive functions-related behavioural problems may contribute to QoL and health status in PwPD and affect caregiver burden. The findings support the view that the concepts of subjective QoL and self-assessed health status are only partially related and should not be seen as identical. Adequate strategies to reduce the impact of EF deficits are needed as this may have the potential to improve QoL in PwPD.

Abstract:
Awareness of executive deficits in people with Parkinson's disease.

Executive functioning is frequently impaired among people with Parkinson's disease (PD). Little is known about awareness of executive functioning, in the sense of being able to accurately appraise functioning or performance, in people with PD, or about whether awareness is particularly affected in those who have impaired executive functioning. This study explored awareness of executive functioning at the levels of evaluative judgment (comparison of self- and informant ratings of executive functioning), and performance monitoring (comparison of performance on cognitive tests and self-ratings of that performance). Awareness levels were assessed in people with PD with and without executive deficits, and in healthy controls. When the level of agreement between self- and informant ratings was considered, people with PD in both groups appeared as accurate in evaluating their overall executive functioning as healthy controls. When appraising their performance as the specific tasks were completed, people with PD who had impairments in executive functioning appeared less accurate than controls and people with PD without executive impairments. People with PD who have executive deficits may lack the ability to recognize their limitations while performing specific tasks, which may have implications for their functional abilities.

Abstract:
Goal-oriented cognitive rehabilitation in early-stage dementia: study protocol for a multi-centre single-blind randomised controlled trial (GREAT).

BACKGROUND: Preliminary evidence suggests that goal-oriented cognitive rehabilitation (CR) may be a clinically effective intervention for people with early-stage Alzheimer's disease, vascular or mixed dementia and their carers. This study aims to establish whether CR is a clinically effective and cost-effective intervention for people with early-stage dementia and their carers. METHODS/DESIGN: in this multi-centre, single-blind randomised controlled trial, 480 people with early-stage dementia, each with a carer, will be randomised to receive either treatment as usual or cognitive rehabilitation (10 therapy sessions over 3 months, followed by 4 maintenance sessions over 6 months). We will compare the effectiveness of cognitive rehabilitation with that of treatment as usual with regard to improving self-reported and carer-rated goal performance in areas identified as causing concern by people with early-stage dementia; improving quality of life, self-efficacy, mood and cognition of people with early-stage dementia; and reducing stress levels and ameliorating quality of life for carers of participants with early-stage dementia. The incremental cost-effectiveness of goal-oriented cognitive rehabilitation compared to treatment as usual will also be examined. DISCUSSION: If the study confirms the benefits and cost-effectiveness of cognitive rehabilitation, it will be important to examine how the goal-oriented cognitive rehabilitation approach can most effectively be integrated into routine health-care provision. Our aim is to provide training and develop materials to support the implementation of this approach following trial completion.

Abstract:
Pattern of executive impairment in mild to moderate Parkinson's disease.

BACKGROUND/AIMS: the exact pattern of impairment in executive functions (EF) among people with Parkinson's disease (PD) is still debated. Using a data-driven approach we investigated which areas of EF are particularly problematic in mild to moderate PD. METHODS: Thirty-four patients with mild to moderate PD, who scored in the normal range on general cognition screening tests, but displayed frontal-type deficits indicated by Frontal Assessment Battery screening, completed the 9 tests that comprise the Delis-Kaplan Executive Function System. Patterns of performance were explored using cluster analysis and principal component analysis (PCA), and the frequency of impairments was established using normative data. RESULTS: Both cluster analysis and PCA identified two distinct groups of EF tests. The first group included tests requiring time-efficient attentional control (e.g. the Trail Making test). The second group included tests measuring abstract reasoning and concept formation abilities (e.g. the 20 Questions test). Impairment was more frequent on the attentional control tests than on the abstract thinking tests. CONCLUSION: PD pathology in the mild to moderate PD appears to affect the attentional control aspect of EF to a greater extent than abstract reasoning. Understanding the nature of executive deficits in PD is important for the development of targeted pharmacological and cognitive interventions for cognitive disturbances.

Abstract:
Executive functions in Parkinson's disease: systematic review and meta-analysis.

Impairment of executive function (EF) is commonly reported as a feature of PD. However, the exact pattern of executive impairment remains unclear. Also, there is an ongoing discussion surrounding the definition and conceptualization of EF, which might affect the clarity of research evidence on cognition in PD. The aim of this systematic review was to describe the pattern of executive impairment in early-stage PD emerging from the research literature and to identify critical issues for improving consistency in this field. The PsychInfo, MEDLINE, Science Direct, CINAHL, and Cochrane Library databases were searched using the term "Parkinson's disease" combined with each of 14 cognitive abilities defined as representing aspects of EF. The review was limited to studies that investigated EF as the central variable in early-stage, nondemented PD patients. The review identified 33 studies of EF that were operationalized in terms of 30 abilities tested by 60 measures and variously interpreted. Many measures were used only once, so only a small part of the available research evidence could be synthesized in the meta-analysis. The meta-analysis was undertaken using data from five commonly used tests of EF drawn from 18 studies. This revealed consistent evidence for cognitive difficulties across all five EF tests. Research on EF in PD is characterized by a considerable lack of clarity with regard to measure selection and interpretation. The findings support the view that EF impairments are evident in PD. However, the clinical significance of the cognitive abnormalities reported has yet to be clarified.