Use of latent variable modeling to delineate psychiatric and cognitive profiles in Parkinson disease

Neurocognitive functioning of patients with early-stage Parkinson's disease

Parkinson's disease (PD) is a neurological disorder commonly associated with motor deficits. However, cognitive impairment is also common in patients with PD. Cognitive concerns in PD may affect multiple domains of neurocognition and vary across different stages of the disease. Extant research has focused mainly on cognitive deficits in middle to late stages of PD, whereas few studies have examined the unique cognitive profiles of patients with early-stage PD. This study addressed this gap in the published literature and examined neurocognitive functioning and functional capacity of patients with de novo PD, focusing on the unique pattern of cognitive deficits specific to the early stage of the disease. Results indicated that the pattern of cognitive deficits in patients with PD (n = 55; mean age = 72.93) was significantly different from healthy controls (n = 59; mean age = 71.88). Specifically, tasks related to executive functioning, attention, and verbal memory demonstrated the most pronounced deficits in patients with early-stage PD. Clinical implications of these findings are discussed.

Annual Prevalence of Use of Potentially Inappropriate Medications for Treatment of Affective Disorders in Parkinson's Disease

OBJECTIVE

To examine the national prevalence of pharmacological treatment of affective disorders in older adults with Parkinson's disease (PD), and determine the prevalence and risk factors for receipt of an American Geriatrics Society Beers Criteria® defined potentially inappropriate medication (PIM) for affective disorder treatment.

DESIGN

Cross-sectional analysis of 2014 Medicare data.

SETTING

Research Identifiable File data from the Centers for Medicare and Medicaid Services.

PARTICIPANTS

Individuals ≥65 years of age with PD whose inpatient, outpatient, and prescription care is administered through the U.S. Medicare Program.

MEASUREMENTS

The 2014 prevalence of affective (i.e., depressive and anxiety) disorders was calculated. We assessed prescription fills for affective disorder treatment and classified prescriptions according to PIM status. Patient and clinician factors associated with PIM prescriptions were determined.

RESULTS

Of 84,323 beneficiaries with PD, 15.1% had prevalent depression only, 7.5% had anxiety only, and 8.5% had comorbid depression and anxiety. Among those with depression only, 80.7% were treated in 2014 (12.8% of treated received at least one PIM). The annual treatment prevalence was 62.9% (75.9% PIM) and 93.1% (63.9% PIM) in the anxiety only and comorbid group, respectively. In most groups, PIM use was less likely among men and those with dementia; geriatricians were less likely to prescribe PIMs.

CONCLUSION

Treatment of affective disorders in persons diagnosed with PD is high. PIM use is also common, particularly in persons with anxiety. Future research will quantify the potential effects of these PIMs on clinical and patient outcomes.

Management of psychiatric disorders in Parkinson's disease : Neurotherapeutics - Movement Disorders Therapeutics

Affective disorders (depression and anxiety), psychosis, impulse control disorders, and apathy are common and sometimes disabling psychiatric conditions in Parkinson disease (PD). Psychiatric aspects of PD are associated with numerous adverse outcomes, yet in spite of this and their high frequency, there remains incomplete understanding of epidemiology, presentation, risk factors, neural substrate, and management strategies. Psychiatric features are typically co- or multimorbid, and there is great intra- and interindividual variability in presentation [1]. The neuropathophysiological changes that occur in PD, as well as the association between PD treatment and particular psychiatric disorders, suggest a neurobiological contribution to many psychiatric symptoms. There is evidence that psychiatric disorders in PD are still under-recognized and undertreated, and although psychotropic medication use is common, randomized controlled trials demonstrating efficacy and tolerability are largely lacking. Future research on neuropsychiatric complications in PD should be oriented toward determining modifiable correlates or risk factors, and most importantly, establishing efficacious and well-tolerated treatment strategies.

The Neuropsychiatry of Parkinson Disease: A Perfect Storm

Affective disorders, cognitive decline, and psychosis have long been recognized as common in Parkinson disease (PD), and other psychiatric disorders include impulse control disorders, anxiety symptoms, disorders of sleep and wakefulness, and apathy. Psychiatric aspects of PD are associated with numerous adverse outcomes, yet in spite of this and their frequent occurrence, there is incomplete understanding of epidemiology, presentation, risk factors, neural substrate, and management strategies. Psychiatric features are typically multimorbid, and there is great intra- and interindividual variability in presentation. The hallmark neuropathophysiological changes that occur in PD, plus the association between exposure to dopaminergic medications and certain psychiatric disorders, suggest a neurobiological basis for many psychiatric symptoms, although psychological factors are involved as well. There is evidence that psychiatric disorders in PD are still under-recognized and undertreated and although psychotropic medication use is common, controlled studies demonstrating efficacy and tolerability are largely lacking. Future research on neuropsychiatric complications in PD should be oriented toward determining modifiable correlates or risk factors and establishing efficacious and well-tolerated treatment strategies.

Education, and the balance between dynamic and stationary functional connectivity jointly support executive functions in relapsing-remitting multiple sclerosis

Graphical network characteristics and nonstationary functional connectivity features, both derived from resting-state functional magnetic resonance imaging (rsfMRI) data, have been associated with cognitive performance in healthy subjects. How these features jointly relate to cognition in diseased states has not been investigated. In this study, 46 relapsing-remitting multiple sclerosis subjects underwent rsfMRI scans and a focused cognitive battery. With a sliding window approach, we examined six dynamic network features that indicated how connectivity changed over time as well as six measures derived from graph theory to reflect static network characteristics. Multiset canonical correlation analysis (MCCA) was then carried out to investigate the relations between dynamic network features, stationary network characteristics, cognitive testing, demographic, disease severity, and mood. Multiple sclerosis (MS) subjects demonstrated weaker connectivity strength, decreased network density, reduced global changes, but increased changes in interhemispheric connectivity compared to controls. The MCCA model determined that executive functions and processing speed ability measured by Wechsler Adult Intelligence Scale IV (WAIS-IV) Working Memory Index, WAIS-IV Processing Speed Index, and the Verbal Fluency Test were positively correlated with education, dynamic connectivity, and static connectivity strength; while poor task switching was correlated with disease severity, psychiatric comorbidities such as depression, anxiety, and fatigue, and static network density. Taken together, our results suggest that better executive functioning in MS requires maintenance of a continued coordination between stationary and dynamic functional connectivity as well as the support of education, and dynamic functional connectivity may provide an additional cognitive biomarker of disease severity in the MS population.

Neuropsychological Subgroups in Non-Demented Parkinson's Disease: A Latent Class Analysis

BACKGROUND

Methods to detect early cognitive decline and account for heterogeneity of deficits in Parkinson's disease (PD) are needed. Quantitative methods such as latent class analysis (LCA) offer an objective approach to delineate discrete phenotypes of impairment.

OBJECTIVE

To identify discrete neurocognitive phenotypes in PD patients without dementia.

METHODS

LCA was applied to a battery of 8 neuropsychological measures to identify cognitive subtypes in a cohort of 199 non-demented PD patients. Two measures were analyzed from each of four domains: executive functioning, memory, visuospatial abilities, and language. Additional analyses compared groups on clinical characteristics and cognitive diagnosis.

RESULTS

LCA identified 3 distinct groups of PD patients: an intact cognition group (54.8%), an amnestic group (32.2%), and a mixed impairment group with dysexecutive, visuospatial and lexical retrieval deficits (13.1%). The two impairment groups had significantly lower instrumental activities of daily living ratings and greater motor symptoms than the intact group. Of those diagnosed as cognitively normal according to MDS criteria, LCA classified 23.2% patients as amnestic and 9.9% as mixed cognitive impairment.

CONCLUSIONS

Non-demented PD patients exhibit distinct neuropsychological profiles. One-third of patients with LCA-determined impairment were diagnosed as cognitively intact by expert consensus, indicating that classification using a statistical algorithm may improve detection of initial and subtle cognitive decline. This study also demonstrates that memory impairment is common in non-demented PD even when cognitive impairment is not clinically apparent. This study has implications for predicting eventual emergence of significant cognitive decline, and treatment trials for cognitive dysfunction in PD.

Pre-clinical cognitive phenotypes for Alzheimer disease: a latent profile approach

BACKGROUND

Cognitive profiles for pre-clinical Alzheimer disease (AD) can be used to identify groups of individuals at risk for disease and better characterize pre-clinical disease. Profiles or patterns of performance as pre-clinical phenotypes may be more useful than individual test scores or measures of global decline.

OBJECTIVE

To evaluate patterns of cognitive performance in cognitively normal individuals to derive latent profiles associated with later onset of disease using a combination of factor analysis and latent profile analysis.

METHODS

The National Alzheimer Coordinating Centers collect data, including a battery of neuropsychological tests, from participants at 29 National Institute on Aging-funded Alzheimer Disease Centers across the United States. Prior factor analyses of this battery demonstrated a four-factor structure comprising memory, attention, language, and executive function. Factor scores from these analyses were used in a latent profile approach to characterize cognition among a group of cognitively normal participants (N = 3,911). Associations between latent profiles and disease outcomes an average of 3 years later were evaluated with multinomial regression models. Similar analyses were used to determine predictors of profile membership.

RESULTS

Four groups were identified; each with distinct characteristics and significantly associated with later disease outcomes. Two groups were significantly associated with development of cognitive impairment. In post hoc analyses, both the Trail Making Test Part B, and a contrast score (Delayed Recall - Trails B), significantly predicted group membership and later cognitive impairment.

CONCLUSIONS

Latent profile analysis is a useful method to evaluate patterns of cognition in large samples for the identification of preclinical AD phenotypes; comparable results, however, can be achieved with very sensitive tests and contrast scores.

Genetically meaningful phenotypic subgroups in autism spectrum disorders

Autism spectrum disorder (ASD) is a complex neurodevelopmental disorder with strong evidence for genetic susceptibility. However, the effect sizes for implicated chromosomal loci are small, hard to replicate and current evidence does not explain the majority of the estimated heritability. Phenotypic heterogeneity could be one phenomenon complicating identification of genetic factors. We used data from the Autism Diagnostic Interview-Revised, Autism Diagnostic Observation Schedule, Vineland Adaptive Behavior Scales, head circumferences, and ages at exams as classifying variables to identify more clinically similar subgroups of individuals with ASD. We identified two distinct subgroups of cases within the Autism Genetic Resource Exchange dataset, primarily defined by the overall severity of evaluated traits. In addition, there was significant familial clustering within subgroups (odds ratio, OR ≈ 1.38-1.42, P < 0.00001), and genotypes were more similar within subgroups compared to the unsubgrouped dataset (Fst = 0.17 ± 0.0.0009). These results suggest that the subgroups recapitulate genetic etiology. Using the same approach in an independent dataset from the Autism Genome Project, we similarly identified two distinct subgroups of cases and confirmed this severity-based dichotomy. We also observed evidence for genetic contributions to subgroups identified in the replication dataset. Our results provide more effective methods of phenotype definition that should increase power to detect genetic factors influencing risk for ASD.

Identifying the Zheng in psoriatic patients based on latent class analysis of traditional Chinese medicine symptoms and signs

Background

There are approximately five Zhengs reported in psoriatic patients. Systematic data collection and proper analysis for the classification of psoriasis have been lacking. This study aims to cluster the Zhengs in psoriatic patients based on the application of a checklist of traditional Chinese medicine (TCM) symptoms and signs followed by latent class analysis (LCA).

Methods

A cross-sectional study of 507 psoriatic patients aged above 10 years was performed in Yunnan Provincial Hospital of TCM and the First Affiliated Hospital of Kunming Medicine University from October 2010 to September 2011 using a TCM symptoms and signs checklist obtained from 16 TCM experts by the Delphi technique. LCA was applied to obtain the best fitted model for clustering of symptoms and signs that can be interpreted as underlying Zhengs of psoriasis.

Results

The LCA identified three Zhengs: dampness-heat Zheng (35.1%); blood heat Zheng (34.7%); and yin deficiency and blood dryness Zheng (30.2%). The first Zheng was associated with winter, the second with male sex, old age, smoking, and drinking alcohol, and the third with outpatient status, which reflected a mild disease course.

Conclusions

In this study, 507 psoriasis patients were clustered into three Zhengs, which had different associated factors.

A latent class analysis of psychological disturbance in Parkinson's disease

OBJECTIVE

Psychological symptoms are common in Parkinson's disease (PD). Psychological symptoms do not respond to psychotropic medications as well in patients with PD as in patients with psychiatric illnesses who do not have PD. Evidence that PD patients can be classified into distinct psychological symptom subgroups is conflicting. This study sought to examine potential psychological heterogeneity in PD with a broader range of instruments than has been used in previous studies.

METHODS

A comprehensive battery of psychological measures assessing dysphoria, apathy, anhedonia, anxiety, and negative affect was administered to 95 PD patients without global cognitive impairment. Latent class analysis was used to identify subgroups of patients based on continuous variables derived from the psychological battery. Multinomial regression was used to examine predictors of classification.

RESULTS

The latent class analysis identified three subgroups with incremental levels of psychopathology across most symptom domains. One exception was a greater level of affective flattening in the "psychologically healthy" group compared with the "moderate symptoms" group. Greater motor dysfunction and less education were associated with greater severity of psychological symptoms.

CONCLUSIONS

These results support high psychological co-morbidity in PD, which complicates the treatment of individual symptoms. In addition, emotional blunting and anhedonia may be less indicative of widespread psychological distress than anxiety, dysphoria, and cognitive aspects of apathy. Clinicians should be aware that PD patients with greater motor dysfunction and less education are at greater risk not only for depression but also for a variety of other psychological symptoms that may not be routinely assessed.

A proposal for a comprehensive grading of Parkinson's disease severity combining motor and non-motor assessments: meeting an unmet need

Background

Non-motor symptoms are present in Parkinson's disease (PD) and a key determinant of quality of life. The Non-motor Symptoms Scale (NMSS) is a validated scale that allows quantifying frequency and severity (burden) of NMS. We report a proposal for using NMSS scores to determine levels of NMS burden (NMSB) and to complete PD patient classification.

Methods

This was an observational, cross-sectional international study of 935 consecutive patients. Using a distribution of NMSS scores by quartiles, a classification based on levels from 0 (no NMSB at all) to 4 (very severe NMSB) was obtained and its relation with Hoehn and Yahr (HY) staging, motor and health-related quality of life scales was analyzed. Concordance between NMSB levels and grouping based on clinician's global impression of severity, using categorical regression, was determined. Disability and HRQoL predictors were identified by multiple regression models.

Results

The distribution of motor and QoL scales scores by HY and NMSB levels was significantly discriminative. The difference in the classification of cases for both methods, HY and NMSB, was significant (gamma = 0.45; ASE = 0.032). Concordance between NMSB and global severity-based levels from categorical regression was 91.8%, (kappa_w = 0.97). NMS score was predictor of disability and QoL.

Conclusions

Current clinical practice does not address a need for inclusion of non-motor scores in routine assessment of PD in spite of the overwhelming influence of NMS on disability and quality of life. Our data overcome the problems of “pure motor assessment” and we propose a combined approach with addition of NMSB levels to standard motor assessments.

Psychosis in Parkinson's disease without dementia: common and comorbid with other non-motor symptoms

Psychosis in Parkinson's disease (PD) is common and associated with a range of negative outcomes. Dementia and psychosis are highly correlated in PD, but the frequency and correlates of psychosis in patients without cognitive impairment are not well understood. One hundred and ninety-one non-demented PD patients at two movement disorders centers participated in a study of neuropsychiatric complications in PD and completed a detailed neurological and neuropsychiatric assessment, including the rater-administered Parkinson Psychosis Rating Scale for hallucinations, delusions, and minor symptoms of psychosis (illusions and misidentification of persons). Psychotic symptoms were present in 21.5% of the sample. Visual hallucinations were most common (13.6%), followed by auditory hallucinations (6.8%), illusions or misidentification of people (7.3%), and paranoid ideation (4.7%). Visual hallucinations and illusions or misidentification of people were the most common comorbid symptoms (3.1%). Depression (P = 0.01) and rapid eye movement behavior disorder symptoms (P = 0.03) were associated with psychosis in a multivariable model. The odds of experiencing psychotic symptoms were approximately five times higher in patients with comorbid disorders of depression and sleep-wakefulness. Even in patients without global cognitive impairment, psychosis in PD is common and most highly correlated with other non-motor symptoms. Screening for psychosis should occur at all stages of PD as part of a broad non-motor assessment. In addition, these findings suggest a common neural substrate for disturbances of perception, mood, sleep-wakefulness, and incipient cognitive decline in PD.

Diagnostic criteria for mild cognitive impairment in Parkinson's disease: Movement Disorder Society Task Force guidelines

Mild cognitive impairment is common in nondemented Parkinson's disease (PD) patients and may be a harbinger of dementia. In view of its importance, the Movement Disorder Society commissioned a task force to delineate diagnostic criteria for mild cognitive impairment in PD. The proposed diagnostic criteria are based on a literature review and expert consensus. This article provides guidelines to characterize the clinical syndrome and methods for its diagnosis. The criteria will require validation, and possibly refinement, as additional research improves our understanding of the epidemiology, presentation, neurobiology, assessment, and long-term course of this clinical syndrome. These diagnostic criteria will support future research efforts to identify at the earliest stage those PD patients at increased risk of progressive cognitive decline and dementia who may benefit from clinical interventions at a predementia stage.

Cognitive impairment in nondemented Parkinson's disease

A substantial percentage of patients with newly diagnosed Parkinson's disease without dementia are reported to be affected by cognitive impairment (CI). In practice, however, CI is underrecognized, as the signs may not be apparent in early-stage disease and many routine assessment tools lack the sensitivity to detect subtle cognitive dysfunction. Patients with PD and mild CI (MCI) may have a higher risk of developing dementia than cognitively intact PD patients; however, it is not currently known which patients with CI are at increased risk of developing dementia. This review summarizes current knowledge about CI in nondemented PD; it discusses the structural and functional changes associated with CI and addresses areas of unmet needs. We focus on questions that should be addressed in future studies to achieve consensus on its characteristics and definition, pathophysiology, epidemiology, diagnosis and assessment, and treatment and management.

MDS Task Force on mild cognitive impairment in Parkinson's disease: critical review of PD-MCI

There is controversy regarding the definition and characteristics of mild cognitive impairment in Parkinson's disease. The Movement Disorder Society commissioned a Task Force to critically evaluate the literature and determine the frequency and characteristics of Parkinson's disease-mild cognitive impairment and its association with dementia. A comprehensive PubMed literature review was conducted using systematic inclusion and exclusion criteria. A mean of 26.7% (range, 18.9%-38.2%) of nondemented patients with Parkinson's disease have mild cognitive impairment. The frequency of Parkinson's disease-mild cognitive impairment increases with age, disease duration, and disease severity. Impairments occur in a range of cognitive domains, but single domain impairment is more common than multiple domain impairment, and within single domain impairment, nonamnestic is more common than amnestic impairment. A high proportion of patients with Parkinson's disease-mild cognitive impairment progress to dementia in a relatively short period of time. The primary conclusions of the Task Force are that: (1) Parkinson's disease-mild cognitive impairment is common, (2) there is significant heterogeneity within Parkinson's disease-mild cognitive impairment in the number and types of cognitive domain impairments, (3) Parkinson's disease-mild cognitive impairment appears to place patients at risk of progressing to dementia, and (4) formal diagnostic criteria for Parkinson's disease-mild cognitive impairment are needed.

Parkinson's disease: the quintessential neuropsychiatric disorder

Although diagnosed by characteristic motor features, Parkinson's disease may be preceded, and is frequently accompanied by, a wide range of cognitive and neuropsychiatric features. In addition to the most commonly studied disorders of dementia, depression, and psychosis, other relatively common and clinically significant psychiatric complications include impulse control disorders, anxiety symptoms, disorders of sleep and wakefulness, and apathy. These problems may be underrecognized and are frequently undertreated. The emergent focus on nonmotor aspects of Parkinson's disease over the past quarter of a century is highlighted by a nonlinear increase in the number of articles published devoted to this topic. Although the development of newer antidepressants, atypical antipsychotics, and cholinesterase inhibitors in recent years has had a positive benefit on the management of these troublesome and distressing symptoms, responses are frequently suboptimal, and this remains an area of major unmet therapeutic need.

Trajectory classes of decline in health-related quality of life in Parkinson's disease: a pilot study

OBJECTIVE

To analyze the change in health-related quality-of-life (HRQoL) in patients with Parkinson's disease (PD) and to identify different classes of HRQoL decline.

METHODS

A longitudinal cohort study was performed to assess clinical parameters (unified PD rating scale, Beck Depression Inventory) and HRQoL data (EuroQol, Parkinson's Disease Questionnaire [PDQ]-39) at baseline, 3, 6, 12, 24, and 36 months. A total of 145 patients with PD were consecutively recruited in the county of Northern Hessia, Germany, between January and June 2000. A latent growth mixture model was applied to analyse the heterogeneity in HRQoL trajectories.

RESULTS

We successfully applied latent mixture growth modeling in order to identify different classes of HRQoL trajectories in PD. Three growth models were developed and each resulted in a four-class model of distinct patterns using the generic EuroQol instruments' outcomes (EuroQol-5 Dimensions and visual analogue scale) and the disease-specific PDQ-39. The four classes were defined by individual trajectory characteristics. Classes one and two represented trajectories with moderate declines over 36 months, but with different initial intercepts. Class three consisted mainly of patients who passed away during the observation period and therefore had a large HRQoL decline. Class four was characterized by a low level of HRQoL at baseline and a significant subsequent decline.

CONCLUSIONS

The findings provide a more elaborate understanding of the variability in HRQoL reduction in PD over time. The classification of different HRQoL subgroups may help to explain the response of PD patients to the natural history of the disease. Future research will enable the identification of HRQoL responder subgroups on different treatment regimens.