Do subjective memory complaints herald the onset of mild cognitive impairment in Parkinson disease?

Cognitive Symptoms in Cross-Sectional Parkinson Disease Cohort Evaluated by Human-in-the-Loop Machine Learning and Natural Language Processing

Background and Objectives

Cognitive impairment is experienced by up to 80% of people with Parkinson disease (PD). Little is known regarding the subjective experience and frequency of bothersome cognitive problems across the range of disease duration as expressed directly in patients' own words. We describe the types and frequency of bothersome cognitive symptoms reported verbatim by patients with PD.

Methods

Through the online Fox Insight study and the Parkinson Disease Patient Report of Problems, we asked patients with PD to self-report by keyboard entry up to five most bothersome problems and how these problems affect their functioning. Human-in-the-loop curation, natural language processing, and machine learning were used to categorize responses into 8 cognitive symptoms: memory, concentration/attention, cognitive slowing, language/word finding, mental alertness/awareness, visuospatial abilities, executive abilities/working memory, and cognitive impairment not otherwise specified. Associations between cognitive symptoms and demographic and disease-related variables were examined in our cross-sectional cohort using multivariate logistic regression.

Results

Among 25,192 participants (55% men) of median age 67 years and 3 years since diagnosis (YSD), 8,001 (32%) reported a cognitive symptom at baseline. The 3 most frequently reported symptoms were memory (13%), language/word finding (12%), and concentration/attention (9%). Depression was significantly associated with bothersome cognitive problems in all domains except visuospatial abilities. Predictors of reporting any cognitive symptom in PD were depression (adjusted OR 1.5), increasing MDS-UPDRS Part II score (OR 1.4 per 10-point increment), higher education (OR 1.2 per year), and YSD 1, 2, 6-7, and 8-9 vs 0 YSD. Among individuals with at least one cognitive symptom, posterior cortical-related cognitive symptoms (i.e., visuospatial, memory, and language) were reported by 17% (n = 4325), frontostriatal-related symptoms (i.e., executive abilities, concentration/attention) by 7% (n = 1,827), and both by 14.2% (n = 1,020). Odds of reporting posterior cortical symptoms vs frontostriatal symptoms increased with age and MDS-UPDRS part II score, but not depression.

Discussion

Nearly one-third of participants with PD, even early in the disease course, report cognitive symptoms as among their most bothersome problems. Online verbatim reporting analyzed by human-in-the-loop curation, natural language processing, and machine learning is feasible on a large scale and allows a detailed examination of the nature and distribution of cognitive symptoms in PD.

Unveiling the role of subjective cognitive complaints in predicting cognitive impairment in Parkinson´s Disease- A longitudinal study with 4 year of follow up

BACKGROUND

Emerging data associated subjective cognitive complaints (SCC) with a heightened risk of future cognitive decline in Parkinson´s Disease (PD).

OBJECTIVE

To determine whether SCC may predict the development of cognitive impairment in PD patients at baseline.

METHODS

Over 4 years, major aspects of motor and non-motor symptoms were assessed. SCC were evaluated by non-motor symptoms scale domain-5 (NMSS5). The predictor value of SCC in cognitive change was assessed with univariate linear regression analyses, with NMSS5 at baseline as predictor. Change in cognition (ΔMoCA) was calculated by subtracting Montreal Cognitive Assessment Scale (MoCA) scores at baseline from scores obtained at reassessment and employed as the outcome. We replicated these analyses by employing alterations in MoCA subdomains as outcomes.

RESULTS

134 patients were evaluated at baseline, of those 73 PD patients were reassessed four years later. In our study, SCC didn´t act as a predictor for future cognitive decline. However, baseline NMSS5 was associated significantly with variation in attention, naming, and orientation domains.

CONCLUSION

Our findings did not support that SCC in PD patients acts as a predictor of global cognitive decline. However, our findings enhance comprehension of how SCC correlates with performance in distinct cognitive areas, thereby providing better guidance for patients on their current complaints.

Neurocognitive Impairment and Social Cognition in Parkinson's Disease Patients

In addition to motor symptoms, neurocognitive impairment (NCI) affects patients with prodromal Parkinson's disease (PD). NCI in PD ranges from subjective cognitive complaints to dementia. The purpose of this review is to present the available evidence of NCI in PD and highlight the heterogeneity of NCI phenotypes as well as the range of factors that contribute to NCI onset and progression. A review of publications related to NCI in PD up to March 2023 was performed using PubMed/Medline. There is an interconnection between the neurocognitive and motor symptoms of the disease, suggesting a common underlying pathophysiology as well as an interconnection between NCI and non-motor symptoms, such as mood disorders, which may contribute to confounding NCI. Motor and non-motor symptom evaluation could be used prognostically for NCI onset and progression in combination with imaging, laboratory, and genetic data. Additionally, the implications of NCI on the social cognition of afflicted patients warrant its prompt management. The etiology of NCI onset and its progression in PD is multifactorial and its effects are equally grave as the motor effects. This review highlights the importance of the prompt identification of subjective cognitive complaints in PD patients and NCI management.

Association between Subjective Cognitive Complaints and Incident Functional Impairment in Parkinson's Disease

BACKGROUND

Early identification of subjective cognitive complaints (SCC) in Parkinson's disease (PD) may improve patient care if it predicts cognition-related functional impairment (CFI).

OBJECTIVES

The aim was to determine the cross-sectional and longitudinal association between SCC and CFI in PD.

METHODS

Data were obtained from Fox Insight, an online longitudinal study that collects PD patient-reported outcomes. Participants completed a PD Patient Report of Problems that asked participants for their five most bothersome disease problems. SCCs were placed into eight categories through human-in-the-loop curation and classification. CFI had a Penn Parkinson's Daily Activities Questionnaire (PDAQ-15) score ≤49. Cox proportional hazards models and Kaplan-Meier survival analyses determined if baseline SCC was associated with incident CFI.

RESULTS

The PD-PROP cohort (N = 21,160) was 55.8% male, mean age was 65.9 years, and PD duration was 4.8 years. At baseline, 31.9% (N = 6750) of participants reported one or more SCCs among their five most bothersome problems, including memory (13.2%), language/word finding (12.5%), and concentration/attention (9.6%). CFI occurred in 34.7% (N = 7332) of participants. At baseline, SCC was associated with CFI (P-value <0.001). SCC at baseline was associated with incident CFI (hazard ratio [HR] = 1.58 [95% confidence interval: 1.45, 1.72], P-value <0.001), as did cognitive impairment not otherwise specified (HR = 2.31), executive abilities (HR = 1.97), memory (HR = 1.85), and cognitive slowing (HR = 1.77) (P-values <0.001). Kaplan-Meier curves showed that by year 3 an estimated 45% of participants with any SCC at baseline developed new-onset CFI.

CONCLUSIONS

Self-reported bothersome cognitive complaints are associated with new-onset CFI in PD. Remote electronic assessment can facilitate widespread use of patient self-report at population scale. © 2024 The Authors. Movement Disorders published by Wiley Periodicals LLC on behalf of International Parkinson and Movement Disorder Society.

A review of the neurotransmitter system associated with cognitive function of the cerebellum in Parkinson's disease

The dichotomized brain system is a concept that was generalized from the 'dual syndrome hypothesis' to explain the heterogeneity of cognitive impairment, in which anterior and posterior brain systems are independent but partially overlap. The dopaminergic system acts on the anterior brain and is responsible for executive function, working memory, and planning. In contrast, the cholinergic system acts on the posterior brain and is responsible for semantic fluency and visuospatial function. Evidence from dopaminergic/cholinergic imaging or functional neuroimaging has shed significant insight relating to the involvement of the cerebellum in the cognitive process of patients with Parkinson's disease. Previous research has reported evidence that the cerebellum receives both dopaminergic and cholinergic projections. However, whether these two neurotransmitter systems are associated with cognitive function has yet to be fully elucidated. Furthermore, the precise role of the cerebellum in patients with Parkinson's disease and cognitive impairment remains unclear. Therefore, in this review, we summarize the cerebellar dopaminergic and cholinergic projections and their relationships with cognition, as reported by previous studies, and investigated the role of the cerebellum in patients with Parkinson's disease and cognitive impairment, as determined by functional neuroimaging. Our findings will help us to understand the role of the cerebellum in the mechanisms underlying cognitive impairment in Parkinson's disease.

A general clinical overview of the non-motor symptoms in Parkinson's disease: Neuropsychiatric symptoms

The heterogeneity of non-motor features observed in people with Parkinson's disease (PD) is often dominated by one or more symptoms belonging to the neuropsychiatric spectrum, such as cognitive impairment, psychosis, depression, anxiety, and apathy. Due to their high prevalence in people with PD (PwP) and their occurrence in every stage of the disease, from the prodromal to the advanced stage, it is not surprising that PD can be conceptualised as a complex neuropsychiatric disorder. Despite progress in understanding the pathophysiological mechanisms underlying the neuropsychiatric signs and symptoms in PD, and better identification and diagnosis of these symptoms, effective treatments are still a major unmet need. The impact of these symptoms on the quality of life of PwP and caregivers, as well as their contribution to the overall non-motor symptom burden can be greater than that of motor symptoms and require a personalised, holistic approach. In this chapter, we provide a general clinical overview of the major neuropsychiatric symptoms of PD.

Subjective Cognitive Complaints in Parkinson's Disease: A Systematic Review and Meta-Analysis

BACKGROUND

Subjective cognitive complaints (SCCs) in Parkinson's disease (PD) are reported frequently, but their prevalence and association with changes on objective testing are not fully known.

OBJECTIVE

We aimed to determine the prevalence, clinical correlates, and predictive value of SCCs in PD.

METHODS

We conducted a systematic review and meta-analysis. From 204 abstracts, we selected 31 studies (n = 3441 patients), and from these, identified the prevalence, clinical features, associations with neuropsychiatric symptoms, and predictive values of SCCs in PD.

RESULTS

The meta-analysis showed an SCC prevalence of 36%. This prevalence, however, was significantly moderated by study heterogeneity regarding female sex, disease severity, levodopa equivalent daily dosage, exclusion from the overall sample of patients with objective cognitive impairment, and measurement instrument. SCC prevalence did not differ between de novo and treated PD patients. SCCs were weakly and negligibly associated with cognitive changes on objective testing in cross-sectional studies. However, in cognitively healthy patients, SCCs had a risk ratio of 2.71 for later cognitive decline over a mean follow-up of 3.16 years. Moreover, SCCs were moderately related to co-occurring symptoms of depression, anxiety, or apathy and were more strongly related to these neuropsychiatric symptoms than objective cognitive functioning.

CONCLUSION

Our analyses suggest that SCCs in patients with and without objective cognitive impairment are frequent, occurring in more than one third of PD patients. Establishing uniform measurement instruments for identifying PD-related SCCs is critical to understand their implications. Even in cases lacking evidence of objective cognitive impairment and where SCCs might reflect underlying neuropsychiatric symptoms, the possibility of later cognitive deterioration should not be excluded. Therefore, SCCs in PD patients warrant close monitoring for opportunities for targeted and effective interventions. © 2024 The Authors. Movement Disorders published by Wiley Periodicals LLC on behalf of International Parkinson and Movement Disorder Society.

Pathobiology of Cognitive Impairment in Parkinson Disease: Challenges and Outlooks

Cognitive impairment (CI) is a characteristic non-motor feature of Parkinson disease (PD) that poses a severe burden on the patients and caregivers, yet relatively little is known about its pathobiology. Cognitive deficits are evident throughout the course of PD, with around 25% of subtle cognitive decline and mild CI (MCI) at the time of diagnosis and up to 83% of patients developing dementia after 20 years. The heterogeneity of cognitive phenotypes suggests that a common neuropathological process, characterized by progressive degeneration of the dopaminergic striatonigral system and of many other neuronal systems, results not only in structural deficits but also extensive changes of functional neuronal network activities and neurotransmitter dysfunctions. Modern neuroimaging studies revealed multilocular cortical and subcortical atrophies and alterations in intrinsic neuronal connectivities. The decreased functional connectivity (FC) of the default mode network (DMN) in the bilateral prefrontal cortex is affected already before the development of clinical CI and in the absence of structural changes. Longitudinal cognitive decline is associated with frontostriatal and limbic affections, white matter microlesions and changes between multiple functional neuronal networks, including thalamo-insular, frontoparietal and attention networks, the cholinergic forebrain and the noradrenergic system. Superimposed Alzheimer-related (and other concomitant) pathologies due to interactions between α-synuclein, tau-protein and β-amyloid contribute to dementia pathogenesis in both PD and dementia with Lewy bodies (DLB). To further elucidate the interaction of the pathomechanisms responsible for CI in PD, well-designed longitudinal clinico-pathological studies are warranted that are supported by fluid and sophisticated imaging biomarkers as a basis for better early diagnosis and future disease-modifying therapies.

Subjective cognitive complaints in patients with progressive supranuclear palsy

Introduction

Subjective cognitive complaints (SCC) refer to self-reported cognitive decline that may or may not be reflected in objective neuropsychological evaluations. Such SCC are prevalent in neurodegenerative diseases, including Parkinson's disease (PD), but the prevalence and clinical features in patients with progressive supranuclear palsy (PSP) have not been investigated.

Methods

We recruited 83 PSP patients without dementia and investigated their SCC using a semi-structured interview. Comprehensive neuropsychological test results and patient clinical features were compared according to presence of SCC and underlying cognitive state.

Results

Among the 83 patients, 16 had normal cognition (NC), 67 had mild cognitive impairment (MCI), and 36 (43.4%) reported SCC. Among NC patients, 37.5% (6/16) had SCC, while 44.8% (30/67) of MCI patients reported SCC. There were no differences between the neuropsychological test results or demographic and clinical characteristics of PSP patients with or without SCC in the NC group. The demographic and clinical characteristics of the MCI+SCC (MCI with SCC)and MCI-SCC (MCI without SCC) groups were comparable, but the MCI+SCC group had significantly worse neuropsychological scores than the MCI-SCC group, particularly in tests assessing attention, language, visual memory, and fronto-executive function domains.

Discussion

While SCC are commonly reported by PSP patients, patients with PSP and MCI+SCC had worse cognitive function than those who did not report SCC. These findings suggest that SCC in PSP patients with MCI could be a worsening sign of cognitive function. Therefore, it is crucial for physicians to assess SCC in PSP patients and to provide timely diagnosis and management of cognitive decline.

Different associated factors of subjective cognitive complaints in patients with early and advanced Parkinson's disease

Subjective cognitive complaints (SCCs), defined as cognitive decline reported by subjects or their informants, are common in the early stage of Parkinson's disease (PD). Previous studies have shown a significant association between SCCs and non-motor features as well as objective cognitive decline in PD patients. However, the discrepancy in SCC prevalence and SCC-related factors between patients with early PD and those with advanced PD remains poorly understood. We recruited a total of 114 and 69 early PD patients and advanced PD patients, respectively. Univariate and multivariate logistic regression analyses were performed for early PD and advanced PD patients. The prevalence of SCCs in the early PD and advanced PD groups was 60.5 and 68.1%, respectively. In the early PD group, the presence of SCCs in early PD participants was significantly associated with a higher nonmotor symptoms questionnaire (NMSQ) score (OR = 1.05, 95% CI = 1.00-1.10, p = 0.040). SCCs in the advanced PD group were related to lower attention scores (OR = 0.24, 95% CI = 0.05-0.90, p = 0.043) and lower visuospatial/executive abilities scores (OR = 0.18, 95% CI = 0.04-0.86, p = 0.032). The prevalence and SCC-related factors are distinct in early PD and advanced PD. These findings suggest that SCCs in PD patients with different disease statuses appear to have different related factors that may depend on different disease severities.

Subjective cognitive decline in patients with Parkinson's disease: an updated review

Cognitive impairment in patients with Parkinson's disease (PD) worsens the prognosis of PD and increases caregivers' burden and economic consequences. Recently, subjective cognitive decline (SCD), which refers to self-reported cognitive decline without detectable objective cognitive dysfunction, has been regarded as an at-risk state of mild cognitive impairment (MCI) and a prodromal stage for dementia in Alzheimer's disease (AD). However, studies on PD-SCD have thus far been scarce, and at present there is no consensus regarding the definition of SCD nor a gold standard as an evaluation tool. The present review aimed to look for an association between PD-SCD and objective cognitive function and found that PD with SCD occurred with brain metabolic changes, which were consistent with early aberrant pathological changes in PD. Moreover, PD patients with SCD were likely to progress to future cognitive impairment. It is necessary to establish a guideline for the definition and evaluation of SCD in PD. A larger sample size and more longitudinal investigations are needed to verify the predictive effectiveness of PD-SCD and to detect earlier subtle cognitive decline before MCI.

Cognitive Impairment in Neurodegenerative Movement Disorders

Patients with neurodegenerative movement disorders can develop cognitive impairment during the disease. Cognitive symptoms have been associated with decreased quality of life, higher caregiver burden, and earlier institutionalization, and are therefore critical for physicians to understand and address. The evaluation of cognitive performance of patients with neurodegenerative movement disorders is important for providing adequate diagnosis, management, prognosis, and support patients and their caregivers. In this review, we discuss the features of the cognitive impairment profile of commonly encountered movement disorders: Parkinson's disease, dementia with Lewy bodies, multiple system atrophy, progressive supranuclear palsy, corticobasal syndrome, and Huntington's disease. In addition, we provide neurologists with practical guidance and evaluation tools for the assessment and management of these challenging patients.

Risk of Cognitive Impairment in Patients With Parkinson's Disease With Visual Hallucinations and Subjective Cognitive Complaints

BACKGROUND AND PURPOSE

Visual hallucinations (VH) and subjective cognitive complaints (SCC) are associated with cognitive impairment (CI) in Parkinson's disease. Our aims were to determine the association between VH and SCC and the risk of CI development in a cohort of patients with Parkinson's disease and normal cognition (PD-NC).

METHODS

Patients with PD-NC (total score of >80 on the Parkinson's Disease Cognitive Rating Scale [PD-CRS]) recruited from the Spanish COPPADIS cohort from January 2016 to November 2017 were followed up after 2 years. Subjects with a score of ≥1 on domain 5 and item 13 of the Non-Motor Symptoms Scale at baseline (V0) were considered as "with SCC" and "with VH," respectively. CI at the 2-year follow-up (plus or minus 1 month) (V2) was defined as a PD-CRS total score of <81.

RESULTS

At V0 (n=376, 58.2% males, age 61.14±8.73 years [mean±SD]), the frequencies of VH and SCC were 13.6% and 62.2%, respectively. VH were more frequent in patients with SCC than in those without: 18.8% (44/234) vs 4.9% (7/142), p<0.0001. At V2, 15.2% (57/376) of the patients had developed CI. VH presenting at V0 was associated with a higher risk of CI at V2 (odds ratio [OR]=2.68, 95% confidence interval=1.05-6.83, p=0.0.039) after controlling for the effects of age, disease duration, education, medication, motor and nonmotor status, mood, and PD-CRS total score at V0. Although SCC were not associated with CI at V2, presenting both VH and SCC at V0 increased the probability of having CI at V2 (OR=3.71, 95% confidence interval=1.36-10.17, p=0.011).

CONCLUSIONS

VH were associated with the development of SCC and CI at the 2-year follow-up in patients with PD-NC.

Subjective Cognitive Complaints in Cognitively Normal Patients With Parkinson's Disease: A Systematic Review

Subjective cognitive complaints (SCCs) refer to self-perceived cognitive decline and are related to objective cognitive decline. SCCs in cognitively normal individuals are considered a preclinical sign of subsequent cognitive impairment due to Alzheimer's disease, and SCCs in cognitively normal patients with Parkinson's disease (PD) are also gaining attention. The aim of this review was to provide an overview of the current research on SCCs in cognitively normal patients with PD. A systematic search found a lack of consistency in the methodologies used to define and measure SCCs. Although the association between SCCs and objective cognitive performance in cognitively normal patients with PD is controversial, SCCs appear to be predictive of subsequent cognitive decline. These findings support the clinical value of SCCs in cognitively normal status in PD; however, further convincing evidence from biomarker studies is needed to provide a pathophysiological basis for these findings. Additionally, a consensus on the definition and assessment of SCCs is needed for further investigations.

Face name matching and memory complaints in Parkinson’s disease

Objective

Memory impairment is a hallmark cognitive deficit in Parkinson’s disease (PD). However, it remains unclear which processes underlie this deficit in PD. Also, little is known on these patients’ subjective experiences of memory difficulties and their relationship with objective measures. We aim to portray memory deficits in PD by combining objective and subjective memory measures.

Methods

Fifteen PD patients and 15 controls were assessed with an extended version of the Face-Name Associative Memory Exam (FNAME) and the Memory Failures of Everyday Questionnaire (MFE-28). We also explored the relationship among clinical and cognitive variables.

Results

Participants with PD presented with more memory complaints. On the FNAME, these patients exhibited lower performance in free recall, as well as in name recognition and matching. Importantly, when controlling for initial learning, group effects disappeared, except for matching. Associative memory therefore was significantly compromised in PD and correlated with subjective memory complaints (SMC).

Conclusion

Our findings suggest that associative memory may constitute a sensitive measure to detect subtle memory deficits in PD. Moreover, the current study further clarifies the source of memory impairment in PD. Thus, our study highlights the clinical value of including associative memory tests such as the FNAME in PD neuropsychological assessment.

Temporal Variation in Disease Onset and Clinical Features of Lewy Body Disease in China

Background: Lewy body dementia is the second most common neurodegenerative dementia, but data concerning the onset age and clinical features in the prodromal stage remain limited in China. Objective: To investigate the associations between onset age and clinical manifestations of cognitive impairment with Lewy bodies in a large-sample cohort. Methods: We included 74 patients with mild cognitive impairment with Lewy bodies (MCI-LB), 533 patients with dementia with Lewy bodies (DLB), 118 patients with Parkinson’s disease with MCI (PD-MCI), and 313 patients with Parkinson’s disease dementia (PDD) in this multicenter cohort from 22 memory clinics of China from 1 January 2018 to 31 March 2022. The onset age, clinical manifestations, and neuropsychological assessments were recorded and analyzed after reviewing the medical records. Results: The average onset age of memory loss was 68.28 (±7.00) years, and parkinsonism happened 2.00 (±1.24) years later for patients with MCI-LB. The average onset age of parkinsonism was 60.56 (±8.96) years, and the memory loss happened 3.49 (±3.02) years later for patients with PD-MCI. Rapid eye movement sleep behavior disorder and visual hallucinations were frequently reported in MCI-LB, DLB, and PDD, while visual hallucinations were least frequently reported in PD-MCI. Lower scores of MMSE and depression, and higher scores of activities of daily living and delusions, were independently associated with older onset age in DLB. Conclusion: The onset of PD-MCI precedes MCI-LB, and memory loss occurs 3 years after parkinsonism. The onset age is associated with cognition and neuropsychiatric symptoms in process.

Specific pattern of linguistic impairment in Parkinson's disease patients with subjective cognitive decline and mild cognitive impairment predicts dementia

OBJECTIVE

Parkinson's disease patients with subjective cognitive decline (PD-SCD) and mild cognitive impairment (PD-MCI) have an increased risk of dementia (PDD). Thus, the identification of early cognitive changes that can be useful predictors of PDD is a highly relevant challenge. Posterior cortically based functions, including linguistic processes, have been associated with PDD. However, investigations that have focused on linguistic functions in PD-MCI are scarce and none of them include PD-SCD patients. Our aim was to study language performance in PD-SCD and PD-MCI. Moreover, language subcomponents were considered as predictors of PDD.

METHOD

Forty-six PD patients and twenty controls were evaluated with a neuropsychological protocol. Patients were classified as PD-SCD and PD-MCI. Language production and comprehension was assessed. Follow-up assessment was conducted to a mean of 7.5 years after the baseline.

RESULTS

PD-MCI patients showed a poor performance in naming (actions and nouns), action generation, anaphora resolution and sentence comprehension (with and without center-embedded relative clause). PD-SCD showed a poor performance in action naming and action generation. Deficit in action naming was an independent risk factor for PDD during the follow-up. Moreover, the combination of deficit in action words and sentence comprehension without a center-embedded relative clause was associated with a greater risk.

CONCLUSIONS

The results are of relevance because they suggest that a specific pattern of linguistic dysfunctions, that can be present even in the early stages of the disease, can predict future dementia, reinforcing the importance of advancing in the knowledge of linguistic dysfunctions in predementia stages of PD.

Prevalence and affective correlates of subjective cognitive decline in patients with de novo Parkinson's disease

OBJECTIVES

The novel concept of subjective cognitive decline (SCD) in Parkinson's disease (PD) refers to subjective cognitive impairment without concurrent objective cognitive deficits. This study aimed to determine the prevalence and affective correlates of SCD in de novo PD patients.

MATERIALS AND METHODS

A total of 139 de novo PD patients underwent comprehensive neuropsychological evaluation. PD patients with SCD (PD-SCD) did not meet the diagnostic criteria for mild cognitive impairment in PD (PD-MCI) based on the Movement Disorder Society Level II Criteria and were defined by a Domain-5 Score ≥1 on the Non-Motor Symptoms Questionnaire. Affective symptoms were measured using the Hamilton Depression Scale (HAMD) and Hamilton Anxiety Scale (HAMA).

RESULTS

In de novo PD cohort, the prevalence of SCD was 28.1%. PD-SCD patients performed significantly better than PD-MCI patients on tests of five cognitive domains. The more commonly affected domains in PD-SCD patients were memory (28.2%) and attention/working memory (25.6%). Multivariable linear regression analysis revealed that PD-SCD was significantly associated with both HAMD (β = 4.518, 95% CI = 0.754-8.281, p = .019) and HAMA scores (β = 4.259, 95% CI = 1.054-7.464, p = .010). Furthermore, binary logistic regression analysis revealed that higher HAMD (OR = 1.128, 95% CI = 1.019-1.249, p = .020) and HAMA scores (OR = 1.176, 95% CI = 1.030-1.343, p = .017) increased the risk of PD-SCD.

CONCLUSIONS

Our findings suggest that SCD is highly prevalent in de novo PD patients. The presence of PD-SCD is suggestive of an underlying affective disorder.

Neural correlates and predictors of subjective cognitive decline in patients with Parkinson's disease

BACKGROUND

Subjective cognitive decline (SCD) may occur very early in the course of Parkinson's disease (PD) before the onset of objective cognitive decline. Data on neural correlates and determinants of SCD in PD are rare.

OBJECTIVE

The aim of the present study was to identify neural correlates as well as sociodemographic, clinical, and neuropsychological predictors of SCD in patients with PD.

METHODS

We retrospectively analyzed 30 patients with PD without cognitive impairment (23% female, 66.90 ± 7.20 years, UPDRS-III: 19.83 ± 9.29), of which n = 12 patients were classified as having no SCD (control group, PD-CG) and n = 18 as having SCD (PD-SCD). Neuropsychological testing and 18-fluoro-2-deoxyglucose positron emission tomography (FDG-PET) were conducted. SCD was assessed using a questionnaire covering multiple cognitive domains.

RESULTS

SCD subscores differed significantly between PD-CG and PD-SCD and correlated significantly with other scales measuring related concepts. FDG-PET whole-brain voxel-wise regression analysis revealed hypometabolism in middle frontal, middle temporal, and occipital areas, and the angular gyrus as neural correlates of SCD in PD. Next to this hypometabolism, depressive symptoms were an independent significant determinant of SCD in a stepwise regression analysis (adjusted R2 = 50.3%).

CONCLUSION

This study strengthens the hypothesis of SCD being an early manifestation of future cognitive decline in PD and, more generally, early pathological changes in PD. The early identification of the vulnerability for future cognitive decline constitutes the basis for successful prevention and delay of this non-motor symptom.

Subjective cognitive decline in idiopathic Parkinson´s disease: A systematic review

Cognitive symptoms of Parkinson's disease (PD) have been long underestimated, but are some of the most disabling non-motor features of the disease. In order to establish signs that allow for earlier detection of cognitive decline in PD, the concept of `subjective cognitive decline´ (SCD) has gained a growing interest. SCD refers to patients who report a decline in subjective cognitive capacities, while their results on neuropsychological tests are within the normal performance range, indicating adequate cognitive functions. The aim of this review was to evaluate the concept of SCD in PD and give an overview of the current research. A systematic literature search in PubMed was performed to identify articles published before December 2020. We included 18 studies with a total of n = 2,654 patients. While there is currently no consensus on research or clinical criteria for SCD in PD, this review presents the accumulated evidence for SCD in PD patients and supports the importance of early identification of cognitive deficits, due to the relatively high prevalence for SCD in PD and the added risk of future cognitive impairment it entails. The publications included in this review indicate that SCD may be part of the PD spectrum but further research is needed. Expanding research on SCD in PD will allow for earlier detection of cognitive impairment and may foster preventive interventions.

Reliability and Validity of the Subjective Cognitive Complaints Questionnaire for Parkinson’s Disease (SCCQ-PD)

Background and Purpose

Subjective cognitive complaints (SCCs) are gaining attention as a self-perceived symptom for cognitive impairment in patients with Parkinson’s disease (PD), but there are few suitable tools for assessing SCCs in PD. This study aimed to develop and validate a questionnaire for assessing SCCs in PD, called the Subjective Cognitive Complaints Questionnaire for Parkinson’s Disease (SCCQ-PD).

Methods

The SCCQ-PD consists of 12 yes/no questions on subjective cognitive function, and the questionnaire was completed by patients with PD (score-P) and their caregivers (score-C). The cognitive function of patients was examined using comprehensive neuropsychological tests.

Results

This study included 73 patients (38 cognitively normal, 25 with mild cognitive impairment [MCI], and 10 demented) and their caregivers. Score-P and score-C had excellent reliability (Kuder-Richardson formula 20 coefficients of 0.893 and 0.931, respectively), and the scores exhibited a strong intercorrelation. Both score-P and score-C were negatively correlated with cognitive performance, and both were excellent in discriminating demented patients from those with normal cognition or MCI (areas under the receiver operating characteristic curve of 0.83 and 0.88, respectively).

Conclusions

The SCCQ-PD is a reliable tool for assessing SCCs in patients with PD. SCCs measured using the SCCQ-PD are correlated with objective cognitive decline and useful for discriminating demented patients from nondemented patients.

Subjective Cognitive Complaints in Newly-Diagnosed Parkinson's Disease With and Without Mild Cognitive Impairment

Background: Subjective cognitive complaints (SCCs) and mild cognitive impairment (MCI) are common among patients with Parkinson's disease (PD). However, the relationship between SCCs and MCI is not well understood. Herein, we aimed to investigate whether there are any differences in the prevalence and risk factors of SCCs between early PD patients with and without MCI. Methods: Overall, 108 newly diagnosed, untreated PD patients underwent comprehensive neuropsychological assessments. PD patients with mild cognitive impairment (PD-MCI) were diagnosed according to the MCI level II criteria. Furthermore, SCCs were measured with the Cognitive Complaints Interview (CCI). Logistic regression analysis, after adjusting for confounding variable, was performed in order to investigate risk factors of SCCs in PD-MCI patients and PD patients with normal cognition (PD-NC). Results: Furthermore, 42 (42.3%) participants reported SCCs and 53 (53.5%) participants were diagnosed with PD-MCI. The prevalence of SCCs in PD-MCI and PD-NC participants was 30.3% and 12.1%, respectively. Logistic regression analyses revealed that the presence of SCCs in PD-MCI group was significantly associated with Non-Motor Symptoms Questionnaire (NMSQ) score (OR = 1.340, 95%CI = 1.115-1.610, p = 0.002), while the presence of SCCs in PD-NC group was significantly associated with time of Stroop Color-Word Test card C (OR = 1.050, 95%CI = 1.009-1.119, p = 0.016). Conclusion: SCCs are frequent among patients with early PD. The prevalence and risk factor of SCCs are distinct in PD with and without MCI. These findings suggest that SCCs in early PD with different cognitive status appear to have different pathogenicity.

Different Associated Factors of Subjective Cognitive Complaints in Patients With Early- and Late-Onset Parkinson's Disease

Background: Subjective cognitive complaints (SCCs), which are associated with a higher risk of cognitive decline, are widespread in the patients with Parkinson's disease (PD). The previous studies have reported inconsistent factors related to SCCs in the patients with late-onset PD (LOPD), and there is limited information on SCCs in the patients with early-onset PD (EOPD). Objective: We aimed to investigate the factors associated with SCCs in the drug-naïve patients with EOPD and LOPD without cognitive impairment. Methods: This cross-sectional study included 332 drug-naïve patients with PD, among whom 134 were EOPD and 198 were LOPD. Motor and non-motor symptoms, such as global objective cognitive status, depression, anxiety, apathy, fatigue, sleep, rapid eye movement sleep behavior disorder, orthostatic hypotension, and excessive daytime sleepiness, were assessed. Results: Twenty-five (18.66%) patients with EOPD and 49 (24.74%) patients with LOPD reported SCCs. A multivariate binary logistic regression analysis revealed that older age at onset [odds ratio (OR) = 1.24, P = 0.002], higher apathy score (OR = 1.13, P = 0.003), and lower scores in the visuospatial/executive abilities (OR = 0.25, P < 0.001) and memory (OR = 0.50, P = 0.024) domains of the Montreal Cognitive Assessment were associated with a higher risk of SCCs in the EOPD group. Higher apathy (OR = 1.06, P = 0.011) and anxiety (OR = 1.14, P < 0.001) scores were associated with SCCs in the LOPD group. Conclusion: Subjective cognitive complaints are only associated with mood disorders in patients with LOPD. In addition, SCCs may reflect subthreshold cognitive impairment in the patients with EOPD.

Disease progression in Parkinson's disease patients with subjective cognitive complaint

Objective

Little is known about the disease progression of Parkinson's disease patients with subjective cognitive complaint (PD‐SCC). This longitudinal cohort study aims to compare the progression of clinical features and quality of life (QoL) in PD patients with normal cognition (NC), SCC, and mild cognitive impairment (MCI).

Methods

A total of 383 PD patients were enrolled, including 189 PD‐NC patients, 59 PD‐SCC patients, and 135 PD‐MCI patients, with 1–7 years of follow‐up. Linear mixed models were applied to evaluate longitudinal changes in motor symptoms, nonmotor features (cognitive impairment, depression, and excessive daytime sleepiness), and QoL in PD.

Results

At baseline, PD‐SCC patients had lower Beck Depression Inventory (BDI) scores and Parkinson's Disease Questionnaire‐39 (PDQ‐39) scores than PD‐NC patients (all p < 0.05). Longitudinal analyses revealed that the PD‐SCC group exhibited faster progression in terms of BDI scores (p = 0.042) and PDQ‐39 scores (p = 0.035) than the PD‐NC group. The PD‐MCI group exhibited faster progression rates in the Epworth Sleepiness Scale scores (p = 0.001) and PDQ‐39 scores (p = 0.005) than the PD‐NC group. In addition, the PD‐SCC group exhibited a greater reduction in attention (Trail Making Test Part A, p = 0.047) and executive function (Stroop Color‐Word Test, p = 0.037) than the PD‐NC group.

Interpretation

PD‐SCC patients exhibited faster deterioration of depression and QoL than PD‐NC patients, and SCC may be an indicator of initial attention and executive function decline in PD. Our findings provided a more accurate prognosis in PD‐SCC patients.

Analyses of Visuospatial and Visuoperceptual Errors as Predictors of Dementia in Parkinson's Disease Patients with Subjective Cognitive Decline and Mild Cognitive Impairment

OBJECTIVE

Subjective cognitive decline (SCD) and mild cognitive impairment (MCI) in Parkinson's disease (PD) are considered as the risk factors for dementia (PDD). Posterior cortically based functions, such as visuospatial and visuoperceptual (VS-VP) processing, have been described as predictors of PDD. However, no investigations have focused on the qualitative analysis of the Judgment of Line Orientation Test (JLOT) and the Facial Recognition Test (FRT) in PD-SCD and PD-MCI. The aim of this work was to study the VS-VP errors in JLOT and FRT. Moreover, these variables are considered as predictors of PDD.

METHOD

Forty-two PD patients and 19 controls were evaluated with a neuropsychological protocol. Patients were classified as PD-SCD and PD-MCI. Analyses of errors were conducted following the procedure described by Ska, Poissant, and Joanette (1990). Follow-up assessment was conducted to a mean of 7.5 years after the baseline.

RESULTS

PD-MCI patients showed a poor performance in JLOT and FRT total score and made a greater proportion of severe intraquadrant (QO2) and interquadrant errors (IQO). PD-SCD showed a poor performance in FRT and made mild errors in JLOT. PD-MCI and QO2/IQO errors were independent risk factors for PDD during the follow-up. Moreover, the combination of both PD-MCI diagnosis and QO2/IQO errors was associated with a greater risk.

CONCLUSIONS

PD-MCI patients presented a greater alteration in VS-VP processing observable by the presence of severe misjudgments. PD-SCD patients also showed mild difficulties in VS-SP functions. Finally, QO2/IQO errors in PD-MCI are a useful predictor of PDD, more than PD-MCI diagnosis alone.

Parkinson disease-associated cognitive impairment

Parkinson disease (PD) is the second most common neurodegenerative disorder, affecting >1% of the population ≥65 years of age and with a prevalence set to double by 2030. In addition to the defining motor symptoms of PD, multiple non-motor symptoms occur; among them, cognitive impairment is common and can potentially occur at any disease stage. Cognitive decline is usually slow and insidious, but rapid in some cases. Recently, the focus has been on the early cognitive changes, where executive and visuospatial impairments are typical and can be accompanied by memory impairment, increasing the risk for early progression to dementia. Other risk factors for early progression to dementia include visual hallucinations, older age and biomarker changes such as cortical atrophy, as well as Alzheimer-type changes on functional imaging and in cerebrospinal fluid, and slowing and frequency variation on EEG. However, the mechanisms underlying cognitive decline in PD remain largely unclear. Cortical involvement of Lewy body and Alzheimer-type pathologies are key features, but multiple mechanisms are likely involved. Cholinesterase inhibition is the only high-level evidence-based treatment available, but other pharmacological and non-pharmacological strategies are being tested. Challenges include the identification of disease-modifying therapies as well as finding biomarkers to better predict cognitive decline and identify patients at high risk for early and rapid cognitive impairment.

Cognitive Impairment in Parkinson's Disease: Epidemiology, Clinical Profile, Protective and Risk Factors

Cognitive impairment is a common non-motor symptom in Parkinson's Disease (PD) and an important source of patient disability and caregiver burden. The timing, profile and rate of cognitive decline varies widely among individuals with PD and can range from normal cognition to mild cognitive impairment (PD-MCI) and dementia (PDD). Beta-amyloid and tau brain accumulation, oxidative stress and neuroinflammation are reported risk factors for cognitive impairment. Traumatic brain injury and pesticide and tobacco exposure have also been described. Genetic risk factors including genes such as COMT, APOE, MAPT and BDNF may also play a role. Less is known about protective factors, although the Mediterranean diet and exercise may fall in this category. Nonetheless, there is conflicting evidence for most of the factors that have been studied. The use of inconsistent criteria and lack of comprehensive assessment in many studies are important methodological issues. Timing of exposure also plays a crucial role, although identification of the correct time window has been historically difficult in PD. Our understanding of the mechanism behind these factors, as well as the interactions between gene and environment as determinants of disease phenotype and the identification of modifiable risk factors will be paramount, as this will allow for potential interventions even in established PD.

Informant-Reported Cognitive Decline is Associated with Objective Cognitive Performance in Parkinson's Disease

OBJECTIVE

The utility of informant-based measures of cognitive decline to accurately describe objective cognitive performance in Parkinson's disease (PD) without dementia is uncertain. Due to the clinical relevance of this information, the purpose of this study was to examine the relationship between informant-based reports of patient cognitive decline via the Informant Questionnaire of Cognitive Decline in the Elderly (IQCODE) and objective cognition in non-demented PD controlling for cognitive status (i.e., mild cognitive impairment; PD-MCI and normal cognition; PD-NC).

METHOD

One-hundred and thirty-nine non-demented PD participants (PD-MCI n = 38; PD-NC n = 101) were administered measures of language, executive function, attention, learning, delayed recall, visuospatial function, mood, and motor function. Each participant identified an informant to complete the IQCODE and a mood questionnaire.

RESULTS

Greater levels of informant-based responses of patient cognitive decline on the IQCODE were significantly associated with worse objective performance on measures of global cognition, attention, learning, delayed recall, and executive function in the overall sample, above and beyond covariates and cognitive status. However, the IQCODE was not significantly associated with language or visuospatial function.

CONCLUSIONS

Results indicate that informant responses, as measured by the IQCODE, may provide adequate information on a wide range of cognitive abilities in non-demented PD, including those with MCI and normal cognition. Findings have important clinical implications for the utility of the IQCODE in the identification of PD patients in need of further evaluation, monitoring, and treatment.

Correlates of the discrepancy between objective and subjective cognitive functioning in non-demented patients with Parkinson's disease

Background

Subjective complaints of cognitive deficits are not necessarily consistent with objective evidence of cognitive impairment in Parkinson’s disease (PD). Here we examined the factors associated with the objective-subjective cognitive discrepancy.

Methods

We consecutively enrolled 90 non-demented patients with PD who completed the Parkinson’s Disease Cognitive Functional Rating Scale (subjective cognitive measure) and the Montreal Cognitive Assessment (MoCA; objective cognitive measure). The patients were classified as “Overestimators”, “Accurate estimators”, and “Underestimators” on the basis of the discrepancy between the objective vs. subjective cognitive measures. To identify the factors distinguishing these groups from each other, we used chi-square tests or one-way analyses of variance, completed by logistic and linear regression analyses.

Results

Forty-nine patients (54.45%) were classified as “Accurate estimators”, 29 (32.22%) as “Underestimators”, and 12 (13.33%) as “Overestimators”. Relative to the other groups, the “Underestimators” scored higher on the Fatigue Severity Scale (FSS), Beck Depression Inventory (BDI), and Parkinson Anxiety Scale (p < 0.01). Logistic regression confirmed that FSS and BDI scores distinguished the “Underestimators” group from the others (p < 0.05). Linear regression analyses also indicated that FSS and BDI scores positively related to objective-subjective cognitive discrepancy (p < 0.01). “Overestimators” scored lower than other groups on the MoCA’s total score and attention and working memory subscores (p < 0.01).

Conclusion

In more than 45% of consecutive non-demented patients with PD, we found a ‘mismatch’ between objective and subjective measures of cognitive functioning. Such discrepancy, which was related to the presence of fatigue and depressive symptoms and frontal executive impairments, should be carefully evaluated in clinical setting.

Supplementary Information

The online version contains supplementary material available at 10.1007/s00415-021-10519-4.

Cross-Cultural Comparisons of Subjective Cognitive Complaints in a Diverse Primary Care Population

BACKGROUND

Very few studies have explored the utility of subjective cognitive complaints (SCCs) in primary care settings.

OBJECTIVE

We aim to investigate associations between SCCs (item-level), objective cognitive function (across domains and global), and mood in a diverse primary care population, including subjects with mild cognitive impairment.

METHODS

We studied 199 (75.9%females; 57.8%Hispanics; 42.2%African Americans) older adults (mean age 72.5 years) with memory concerns at a primary care clinic. A five-item SCC questionnaire, and objective cognitive assessments, including the Montreal Cognitive Assessment (MoCA) and the Geriatric Depression Scale, were administered.

RESULTS

Logistic regression analyses showed associations between SCC score and depressive symptoms. A memory-specific ("memory worsening") SCC predicted scores on the MoCA (p = 0.005) in Hispanics.

CONCLUSION

SCCs are strongly linked to depressive symptoms in African Americans and Hispanics in a primary care setting; a specific type of SCC is related to global cognitive function in Hispanics.

Parkinson disease with mild cognitive impairment: Domain-specific cognitive complaints predict dementia

BACKGROUND

The presence of subjective cognitive complaints (SCC) as a predictor of cognitive impairment in Parkinson´s disease (PD) has shown conflicting results. Most previous studies only assessed complaints in the memory domain. We investigate the association of SCCs across cognitive domains with development of mild cognitive impairment (PD-MCI) and dementia (PDD) in PD and to assess agreement between SCCs and objective cognitive impairments in this population.

METHODS

This is a retrospective analysis of a prospective cohort study. Participants were enrolled at six North-American movement disorders centers. They underwent neuropsychological and non-cognitive clinical evaluations, including the modified Neurobehavioral Inventory to elicit SCC (rated by each patient and independently by their close contact (CC)). Associations between SCCs and development of future cognitive impairment were assessed. Agreement between SCCs and objective impairment within the same domain was also calculated.

RESULTS

Of 138 included PD patients, 42% fulfilled criteria for PD-MCI. None of the NBI items predicted development of cognitive impairment after one and two years in PD with normal cognition. In PD-MCI patients, SCCs related to attention predicted dementia at year one. CC ratings of SCCs related to memory and language problems predicted PDD in PD-MCI patients. According to CC reported patients' complaints, there was a significant agreement between SCCs and objective cognitive test scores on attention.

CONCLUSIONS

Eliciting SCCs including cognitive domains other than memory is crucial for a complete evaluation, including both patient and CC report. Memory, language, and especially attention SCCs in PD-MCI may predict progression to dementia.

Subjective cognitive Complaints in early Parkinson's disease patients with normal cognition are associated with affective symptoms

INTRODUCTION

Subjective cognitive complaints (SCC) and affective symptoms are highly prevalent in Parkinson's Disease (PD). In early PD, SCC prevalence and its affective correlates, using recommended Movement Disorders Society (MDS) Level II Criteria to define the underlying cognitive impairment, has not been previously explored.

METHODS

We recruited 121 participants with early PD from two tertiary hospitals in Singapore. The presence of SCC was defined using a Non-Motor Symptoms Scale Domain-5 Score ≥1. Comprehensive neuropsychological testing was conducted with Mild Cognitive Impairment (PD-MCI) defined using recommended MDS Level II Criteria. Affective symptoms were assessed using the Hospital Anxiety Depression Scale (HADS), Geriatric Depression Scale (GDS) and Apathy Scale (AS). Analysis using multivariable linear regression model was performed.

RESULTS

In our early PD cohort, SCC prevalence independent of underlying cognitive status was 38.8%. Prevalence of SCC in cognitively impaired and cognitively normal participants was 10.7% and 28.1% respectively (р = 0.241). In cognitively normal PD participants, multivariable linear regression analysis revealed that SCC was significantly associated with anxiety (β = 0.28, 95% CI = 0.09-0.79, p = 0.014), depression (β = 0.31, 95% CI = 0.10-0.59, p = 0.006) and apathy (β = 0.32, 95% CI = 1.15-5.98, p = 0.004). Such an association was not found in cognitively impaired PD participants.

CONCLUSION

SCC is highly prevalent even in early PD. Its implications in early PD differ depending on underlying cognitive status. SCC in cognitively impaired participants underestimates the true prevalence of PD-MCI. In contrast, SCC in cognitively normal participants is suggestive of an underlying affective disorder.

Disentangling the Role of Working Memory in Parkinson's Disease

Working memory (WM) represents a core cognitive function with a major striatal contribution, and thus WM deficits, commonly observed in Parkinson’s disease (PD), could also relate to many other problems in PD patients. Our online study aimed to determine the subdomains of WM that are particularly affected in PD and to clarify the links between WM and everyday cognitive deficits, other executive functions, psychiatric and PD symptoms, as well as early cognitive impairment. Fifty-two mild-to-moderate PD patients and 54 healthy controls performed seven WM tasks tapping selective updating, continuous monitoring, or maintenance of currently active information. Self-ratings of everyday cognition, depression, and apathy symptoms, as well as screenings of global cognitive impairment, were also collected. The data were analyzed using structural equation modeling. Of the three WM domains, only selective updating was directly predictive of PD group membership. More widespread WM deficits were observed only in relation to global cognitive impairment in PD patients. Self-rated everyday cognition or psychiatric symptoms were not linked to WM performance but correlated with each other. Our findings suggest that WM has a rather limited role in the clinical manifestation of PD. Nevertheless, due to its elementary link to striatal function, the updating component of WM could be a candidate for a cognitive marker of PD also in patients who are otherwise cognitively well-preserved.

Patient and Clinician Impressions of Cognitive Impairment in Parkinson's Disease

We investigated patient and clinician impressions of cognitive impairment and whether they correlated with objective measures of cognitive impairment. Cognitive categorization, neuropsychological assessment scores, and Montreal Cognitive Assessment scores were documented at baseline, 3 years, and 7 years for 388 PD patients in the Parkinson's Progression Markers Initiative (PPMI). We found that both patient and clinician impressions of cognitive decline were significantly associated with gold-standard criteria for cognitive impairment to a similar degree. Both patient and clinician perspectives should be considered in determining cognitive status and should be followed up with diagnostic testing.

Subjective Cognitive Complaint in Parkinson's Disease Patients With Normal Cognition: Canary in the Coal Mine?

OBJECTIVE

The objective of this study was to determine the frequency and impact of subjective cognitive complaint (SCC) in Parkinson's disease (PD) patients with normal cognition.

METHODS

Patients with PD with expert consensus-determined normal cognition at baseline were asked a single question regarding the presence of SCC. Baseline (N = 153) and longitudinal (up to 4 follow-up visits during a 5-year period; N = 121) between-group differences in patients with PD with (+SCC) and without (-SCC) cognitive complaint were examined, including cognitive test performance and self-rated and informant-rated functional abilities.

RESULTS

A total of 81 (53%) participants reported a cognitive complaint. There were no between-group differences in global cognition at baseline. Longitudinally, the +SCC group declined more than the -SCC group on global cognition (Mattis Dementia Rating Scale-2 total score, F_1,431 = 5.71, P = 0.02), processing speed (Symbol Digit Modalities Test, F_1,425 = 7.52, P = 0.006), and executive function (Trail Making Test Part B, F_1,419 = 4.48, P = 0.04), although the results were not significant after correction for multiple testing. In addition, the +SCC group was more likely to progress to a diagnosis of cognitive impairment over time (hazard ratio = 2.61, P = 0.02). The +SCC group also demonstrated significantly lower self-reported and knowledgeable informant-reported cognition-related functional abilities at baseline, and declined more on an assessment of global functional abilities longitudinally.

CONCLUSIONS

Patients with PD with normal cognition, but with SCC, report poorer cognition-specific functional abilities, and are more likely to be diagnosed with cognitive impairment and experience global functional ability decline long term. These findings suggest that SCC and worse cognition-related functional abilities may be sensitive indicators of initial cognitive decline in PD. © 2020 International Parkinson and Movement Disorder Society.

Cognitive Complaints in Nondemented Parkinson's Disease Patients and Their Close Contacts do not Predict Worse Cognitive Outcome

OBJECTIVES

The main purpose of this study was to investigate 4 methods of eliciting subjective cognitive complaints (SCCs) in Parkinson's disease (PD) patients without dementia and determine the relationship between their SCC and cognitive performance.

DESIGN

This study was a retrospective analysis of a prospective cohort study.

SETTING

Six North American movement disorder clinics.

MEASUREMENTS

SCCs were elicited through a modified Neurobehavioral Inventory administered to patients and close contacts, a general complaint question, and Movement Disorders Society Unified Parkinson's Disease Rating Scale item question 1.1 administered to patients. Clinical evaluation, formal neuropsychological testing and Disability Assessment for Dementia were conducted in Ontario state. Agreement between SCCs eliciting methods was calculated. Associations between SCC, cognitive testing, and mild cognitive impairment (MCI) were assessed.

RESULTS

Of 139 participating nondemented PD patients, 42% had PD-MCI at baseline. Agreement between SCC eliciting methods was low. Neither patient-reported nor close contact-reported SCCs were associated with impaired baseline cognitive testing or PD-MCI nor were they associated with cognitive decline over time. In PD patients with normal baseline cognition, 26% of patients with 1-year follow-up and 20% of patients with 2-year follow-up met MCI criteria.

CONCLUSIONS

Agreement between SCC eliciting methods is poor and no SCC method was associated with cognitive testing or decline over time. With no clear superior method for eliciting SCCs, clinicians should consider performing regular screening.

Subjective cognitive complaints in patients with Parkinson's disease

Mild cognitive impairment (MCI) is common in Parkinson's disease (PD), affecting almost all patients with PD at some time. It has been shown that patients with PD, who express subjective cognitive complaints, are at a higher risk of eventually developing PD-MCI. This is corroborated by the Movement Disorders Society's (MDS) diagnostic criteria from 2012 for PD-MCI, from which it follows that a subjective cognitive complaint must be present in addition to objective cognitive impairment for a patient with PD to receive a diagnosis of PD-MCI. Nevertheless, there is currently no standardized measurement available for assessing subjective cognitive complaints. Therefore, this review aims to generate an overview of how subjective cognitive complaints are commonly operationalized in the empirical literature as well as whether they are found to be associated with the level of cognitive impairment. The findings revealed that a broad range of measures has been used to obtain subjective cognitive complaints and that there is little consistency between different studies with regard to how they have obtained these complaints, from whom they had obtained them, how many they have obtained, which types of complaints they have obtained and whether they were associated with cognitive impairment. Given the fact that the presence of subjective cognitive complaints is a requirement for setting a diagnosis, there is a need for more methodological consensus with regard to the measurement hereof.

Subjective memory decline in Parkinson's disease patients with and without fatigue

INTRODUCTION

Previous studies on Parkinson's disease (PD) have shown that memory complaints and fatigue co-occur since premotor stages of disease, but whether Subjective Memory Decline (SMD, defined as memory complaints with normal objective cognitive performance) and fatigue were associated in PD has not been explored yet.

METHODS

One-hundred PD patients underwent measures of memory complaints (Multifactorial Memory Questionnaire, MMQ), neuropsychological test (Parkinson's Disease-Cognitive Rating Scale), and assessment of behavioural symptoms. Fatigue was diagnosed according to current diagnostic criteria. Mann-Whitney test or Pearson chi-square test were used to compare fatigued and nonfatigued patients for prevalence of SMD and for demographic, clinical, and behavioural features, memory complaint, and objective cognitive measures. The confounding effect of sample's features on results was controlled by logistic regression and Quade's rank analysis.

RESULTS

Twenty-three patients were diagnosed as fatigued whereas 15 patients met SMD criteria. Fatigued patients showed higher levodopa equivalent daily dose and more marked behavioural symptoms than nonfatigued patients (p_s< 0.01). The prevalence of SMD was higher in fatigued patients than in those nonfatigued (35% vs 9%, p < 0.01). After controlling for confounds, the patients with fatigue had an odds ratio for SMD 5.97 [CI 95%, 1.18-30.03] times higher and presented significantly lower scores on Contentment subscales of MMQ (p < 0.01) than those without fatigue.

CONCLUSION

Fatigue in PD is associated with SMD mainly characterized by less contentment with one's own memory ability. These findings suggest possible shared pathogenic mechanisms underlying these two nonmotor manifestations and foster to identify potential phenotypes of patients requiring multistrategic therapeutic approaches.

Cognitive complaints in Parkinson's disease patients: from subjective cognitive complaints to dementia and affective disorders

Subjective cognitive complaints (SCC) are frequent in elderly populations. PD patients report SCC more often than healthy controls. The association between SCC, objective cognitive impairment and affective symptoms remains controversial. We assessed consecutive PD patients between March 2014 and March 2015. Presence of SCC was defined as a score ≥ 1 in the Non-Motor Symptom Assessment Scale for Parkinson's Disease (NMSS) Domain 5. MoCA was used for cognitive impairment assessment. Pill Questionnaire measured the impact in daily activities. PD with Dementia (PDD) and PD with Mild Cognitive Impairment (PDMCI) were defined as the presence of cognitive impairment with or without impact on daily activities. Anxiety and depression were assessed using the Hospital Anxiety and Depression Scales. Significance was set at p < 0.05. From 134 patients, 128 were included. PDD was diagnosed in 21 (16.4%), PDMCI in 31 (24.2%), and 76 (59.4%) had normal cognition (PDCN). SCC were present in 85% of whole cohort and evenly distributed (p = 0.361), PDD (95.2%), PDMCI (83.9%) and PDCN (82.9%). Severity was significantly different between PDD (20.00 ± 10.81), PDMCI (6.54 ± 5.5) and PDCN (6.97 ± 6.98), p < 0.001. A score ≥ 19 had a specificity of 77.3% and a sensitivity of 78.8% for identifying PDD. In PDCN, SCC severity was found to be related to depression (OR 1.23, CI 95% 1.02-1.47, p = 0.026) more than with MoCA scores (OR: 0.86, CI 95% 0.69-1.05, p = 0.141). SCC are common in PD. Their severity can help distinguish PDD from non-demented PD patients. In PDCN, SCC should alert the clinician for an affective disorder.

Frequency and Correlates of Subjective Memory Complaints in Parkinson's Disease with and without Mild Cognitive Impairment: Data from the Parkinson's Disease Cognitive Impairment Study

Subjective memory complaints (SMC) may represent the preclinical phase of mild cognitive impairment (MCI) due to Alzheimer's disease. Dementia/MCI have been described with a high prevalence in Parkinson's disease (PD), but whether SMC may predict the development of cognitive impairment has been barely explored. To evaluate the frequency and clinical correlates of isolated SMC (PD-SMC) or within the construct of MCI in subjects with PD, 147 PD patients from the PArkinson's disease COgnitive impairment Study (PACOS) were consecutively recruited for the study. This is a multicenter study involving two Movement Disorder Centers in south Italy. All subjects underwent comprehensive neuropsychological evaluation and PD-MCI was diagnosed according to Litvan's criteria. The Memory Assessment Clinics Questionnaire was used to assess SMC. Logistic regression analysis, adjusted for demographics and significant covariates, was used to evaluate clinical differences between groups. Forty-two (28.6%) individuals presented with PD without SMC and/or MCI (PDw), 40 (27,2%) with PD-SMC, 48 (32,6%) PD-SMC-MCI, and 17 (11,6%) PD-MCI without SMC (PD-MCI). When compared to PDw, PD-SMC was significantly associated with anxiety (OR = 3.93, 95% CI = 1.18-13.03), while PD-SMC-MCI related to motor progression (OR = 5.29, 95% CI = 1.12-24.86), and instrumental disability (OR = 6.98, 95% CI = 2.08-23.38). About 60% of patients showed SMC, in isolation or within the MCI frame. The role of SMC in PD seems to have a different etiology depending on the presence/absence of MCI. In particular, PD-SMC would represent a subjective reaction to the disease, while PD-SMC-MCI would depict motor progression and disability.

Novel Treatment Opportunities Against Cognitive Impairment in Parkinson's Disease with an Emphasis on Diabetes-Related Pathways

Cognitive impairment is highly prevalent in patients with Parkinson's disease (PD) and causes adverse health outcomes. Novel procognitive therapies are needed to address this unmet need. It is now established that there is an increased risk of dementia in patients with type 2 diabetes mellitus (T2DM) and, moreover, T2DM and PD may have common underlying biological mechanisms. As such, T2DM medications are emerging as potential therapies in the context of PD dementia (PDD). In this review, we provide an update on pathophysiological mechanisms underlying cognitive impairments and PDD, focusing on diabetes-related pathways. Finally, we have conducted a review of ongoing clinical trials in PD patients with dementia, highlighting the multiple pharmacological mechanisms that are targeted to achieve cognitive enhancement.

Predicting early cognitive decline in newly-diagnosed Parkinson's patients: A practical model

OBJECTIVE

To create a multivariable model to predict early cognitive decline among de novo patients with Parkinson's disease, using brief, inexpensive assessments that are easily incorporated into clinical flow.

METHODS

Data for 351 drug-naïve patients diagnosed with idiopathic Parkinson's disease were obtained from the Parkinson's Progression Markers Initiative. Baseline demographic, disease history, motor, and non-motor features were considered as candidate predictors. Best subsets selection was used to determine the multivariable baseline symptom profile that most accurately predicted individual cognitive decline within three years.

RESULTS

Eleven per cent of the sample experienced cognitive decline. The final logistic regression model predicting decline included five baseline variables: verbal memory retention, right-sided bradykinesia, years of education, subjective report of cognitive impairment, and REM behavior disorder. Model discrimination was good (optimism-adjusted concordance index = .749). The associated nomogram provides a tool to determine individual patient risk of meaningful cognitive change in the early stages of the disease.

CONCLUSIONS

Through the consideration of easily-implemented or routinely-gathered assessments, we have identified a multidimensional baseline profile and created a convenient, inexpensive tool to predict cognitive decline in the earliest stages of Parkinson's disease. The use of this tool would generate prediction at the individual level, allowing clinicians to tailor medical management for each patient and identify at-risk patients for clinical trials aimed at disease modifying therapies.

Memory complaints, dementia, and neuropathology in older blacks and whites

OBJECTIVE

To determine relationships of memory complaints to cognitive function and decline, incident dementia, and neurodegenerative and other neuropathologies, as well as the population-attributable risk for dementia in older black and white persons.

METHODS

A total of 4,015 community-based persons (28% black; 74% women; mean baseline age = 78 years) were enrolled in 1 of 4 longitudinal cohort studies, and another 2,937 in a population-based cohort. Memory scores, assessed using 2 questions (5-point Likert scales) were categorized as complaints present or absent. Global cognition and 5 cognitive domains were derived from annual neuropsychological tests. Dementia was assessed from these tests and additional data. Neuropathologic data were available for 1,350 deceased subjects with brain autopsies. Regression and mixed effects models were used to examine relationships of memory complaints to cognition and neuropathology.

RESULTS

Baseline memory complaints (n = 1,310; 33% of 4,015) were associated with lower cognition and faster decline in all domains (global score estimate = -0.032, standard error = 0.004, p < 0.0001), during a mean follow-up of 6 (standard deviation = 2) years. Persons with memory complaints had higher dementia risk (hazard ratio = 1.64, 95% confidence interval [CI] = 1.42-1.89) and odds of pathologic Alzheimer disease (odds ratio [OR] = 1.96, 95% CI = 1.51-2.54), neocortical Lewy bodies (OR = 2.47, 95% CI = 1.54-3.96), and other neurodegenerative pathologies. Results for dementia risk were similar among blacks and whites. Among 2,937 older persons in a population-based cohort with similar data, the population-attributable risk for incident dementia due to memory complaints was 14.0% (95% CI = 2.6-23.0), and did not vary between the black and white groups.

INTERPRETATION

Memory complaints are common in older black and white persons, and relate to cognitive decline, dementia risk, and neurodegenerative pathologies. Ann Neurol 2018;83:718-729.

Nonmotor Subtyping in Parkinson's Disease

Nonmotor symptoms are integral to Parkinson's disease. Several subtypes dominated by specific nonmotor symptoms have emerged. In this chapter, the rationale behind nonmotor subtyping and currently proposed nonmotor subgroups within Parkinson's disease based on data-driven cluster analysis and clinical observations will be summarized. Furthermore, the concept of seven clinical nonmotor subtypes will be discussed in detail including the clinical presentation, potential biomarkers, and the clinical relevance. In future, nonmotor subtypes will possibly play a major role within the aim to achieve personalized medicine.

Cognitive decline in Parkinson disease

Dementia is a frequent problem encountered in advanced stages of Parkinson disease (PD). In recent years, research has focused on the pre-dementia stages of cognitive impairment in PD, including mild cognitive impairment (MCI). Several longitudinal studies have shown that MCI is a harbinger of dementia in PD, although the course is variable, and stabilization of cognition - or even reversal to normal cognition - is not uncommon. In addition to limbic and cortical spread of Lewy pathology, several other mechanisms are likely to contribute to cognitive decline in PD, and a variety of biomarker studies, some using novel structural and functional imaging techniques, have documented in vivo brain changes associated with cognitive impairment. The evidence consistently suggests that low cerebrospinal fluid levels of amyloid-β₄₂, a marker of comorbid Alzheimer disease (AD), predict future cognitive decline and dementia in PD. Emerging genetic evidence indicates that in addition to the APOE*ε4 allele (an established risk factor for AD), GBA mutations and SCNA mutations and triplications are associated with cognitive decline in PD, whereas the findings are mixed for MAPT polymorphisms. Cognitive enhancing medications have some effect in PD dementia, but no convincing evidence that progression from MCI to dementia can be delayed or prevented is available, although cognitive training has shown promising results.

Implementation of subjective cognitive decline criteria in research studies

INTRODUCTION

Subjective cognitive decline (SCD) manifesting before clinical impairment could serve as a target population for early intervention trials in Alzheimer's disease (AD). A working group, the Subjective Cognitive Decline Initiative (SCD-I), published SCD research criteria in the context of preclinical AD. To successfully apply them, a number of issues regarding assessment and implementation of SCD needed to be addressed.

METHODS

Members of the SCD-I met to identify and agree on topics relevant to SCD criteria operationalization in research settings. Initial ideas and recommendations were discussed with other SCD-I working group members and modified accordingly.

RESULTS

Topics included SCD inclusion and exclusion criteria, together with the informant's role in defining SCD presence and the impact of demographic factors.

DISCUSSION

Recommendations for the operationalization of SCD in differing research settings, with the aim of harmonization of SCD measurement across studies are proposed, to enhance comparability and generalizability across studies.