Domain-specific cognitive impairment in non-demented Parkinson's disease psychosis

Characterizing the relationship between L-DOPA-induced-dyskinesia and psychosis-like behaviors in a bilateral rat model of Parkinson's disease

Parkinson's disease associated psychosis (PDAP) is a prevalent non-motor symptom (NMS) that significantly erodes patients' and caregivers' quality of life yet remains vastly understudied. One potential source of PDAP in late-stage Parkinson's disease (PD) is the common dopamine (DA) replacement therapy for motor symptoms, Levodopa (L-DOPA). Given the high incidence of L-DOPA-induced dyskinesia (LID) in later phases of PD, this study sought to characterize the relationship between PDAP and LID in a bilateral medial forebrain bundle 6-hydroxydopamine hydrobromide (6-OHDA) lesion rat model. To assess PDAP in this model, prepulse inhibition (PPI), a well-validated assay of sensorimotor gating, was employed. First, we tested whether a bilateral lesion alone or after chronic L-DOPA treatment was sufficient to induce PPI dysfunction. Rats were also monitored for LID development, using the abnormal involuntary movements (AIMs) test, to examine PPI and LID associations. In experiment 2, Vilazodone (VZD), a serotonin transporter (SERT) blocker and 1A receptor (5-HT_1A) partial agonist was administered to test its potential efficacy in reducing LID and PPI dysfunction. Once testing was complete, tissue was collected for high performance liquid chromatography (HPLC) to examine the monoamine levels in motor and non-motor circuits. Results indicate that bilateral DA lesions produced motor deficits and that chronic L-DOPA induced moderate AIMs; importantly, rats that developed more severe AIMs were more likely to display sensorimotor gating dysfunction. In addition, VZD treatment dose-dependently reduced L-DOPA-induced AIMs without impairing L-DOPA efficacy, although VZD's effects on PPI were limited. Altogether, this project established the bilateral 6-OHDA lesion model accurately portrayed LID and PDAP-like behaviors, uncovered their potential relationship, and finally, demonstrated the utility of VZD for reducing LID.

Adherence to High Dietary Diversity and Incident Cognitive Impairment for the Oldest-Old: A Community-Based, Nationwide Cohort Study

BACKGROUND AND AIMS

Dietary diversity change is associated with cognitive function, however, whether the effect still exists among the oldest-old (80+) is unclear. Our aim was to examine the effect of dietary diversity changes on cognitive impairment for the oldest-old in a large prospective cohort.

METHODS

Within the Chinese Longitudinal Healthy Longevity Study, 6237 adults older than 80 years were included. The dietary diversity score (DDS) was assessed by a simplified food frequency questionnaire (FFQ). Cognitive impairment was defined as a Mini-Mental State Examination (MMSE) score lower than 18 points. Cognitive decline was defined as a reduction of total MMSE score ≥3 points, and cognitive decline of different subdomains was defined as a reduction of ≥15% in the corresponding cognitive domain. The multivariate-adjusted Cox proportional hazard model evaluated the effects of DDS change on cognitive decline. The linear mixed-effect model was used to test subsequent changes in MMSE over the years.

RESULTS

During 32,813 person-years of follow-up, 1829 participants developed cognitive impairment. Relative to the high-high DDS change pattern, participants in the low-low and high-low patterns were associated with an increased risk of cognitive impairment with a hazard ratio (95% confidential interval, CI) of 1.43 (1.25, 1.63) and 1.44 (1.24, 1.67), and a faster decline in the MMSE score over the follow-up year. Participants with the low-high pattern had a similar incidence of cognitive impairment with HRs (95% CI) of 1.03 (0.88, 1.20). Compared with the stable DDS status group (-1-1), the risk of cognitive impairment was higher for those with large declines in DDS (≤-5) and the HR was 1.70 (95% CI: 1.44, 2.01).

CONCLUSIONS

Even for people older than 80, dietary diversity change is a simple method to identify those who had a high risk of cognitive decline. Keeping high dietary diversity is beneficial for cognitive function and its subdomain even in the final phase of life, especially for females and the illiterate oldest-old.

Cognitive dysfunction and neuropsychiatric aspects of Parkinson's disease

Movement abnormalities, by definition, and cognitive changes, to varying extents, affect every patient with Parkinson's disease (PD) and are attributed to the underlying neurodegenerative disease. Various psychiatric disorders occur in most patients at some point over the course of PD, including in the prodromal phase. Even though psychiatric disturbances tend to aggravate motor and cognitive deficits, they are under-recognized and under-treated, and the role of the underlying neurological disease is often minimized. To provide an integrated approach to understanding neuropsychiatric aspects of PD, this chapter reviews how cognitive changes in PD relate to the common psychiatric disturbances in PD along with the prevalence, phenomenology, pathophysiology, and treatment of each.

Remote self-administration of digital cognitive tests using the Brief Assessment of Cognition: Feasibility, reliability, and sensitivity to subjective cognitive decline

Cognitive impairment is a common and pervasive feature of etiologically diverse disorders of the central nervous system, and a target indication for a growing number of symptomatic and disease modifying drugs. Remotely acquired digital endpoints have been recognized for their potential in providing frequent, real-time monitoring of cognition, but their ultimate value will be determined by the reliability and sensitivity of measurement in the populations of interest. To this end, we describe initial validation of remote self-administration of cognitive tests within a regulatorily compliant tablet-based platform. Participants were 61 older adults (age 55+), including 20 individuals with subjective cognitive decline (SCD). To allow comparison between remote (in-home) and site-based testing, participants completed 2 testing sessions 1 week apart. Results for three of four cognitive domains assessed demonstrated equivalence between remote and site-based tests, with high cross-modality ICCs (absolute agreement) for Symbol Coding (ICC = 0.75), Visuospatial Working Memory (ICC = 0.70) and Verbal Fluency (ICC > 0.73). Group differences in these domains were significant and reflected sensitivity to objective cognitive impairment in the SCD group for both remote and site-based testing (p < 0.05). In contrast, performance on tests of verbal episodic memory suggested inflated performance during unmonitored testing and indicate reliable use of remote cognitive assessments may depend on the construct, as well as the population being tested.

Frequency and Characteristics of Psychosis in Parkinson's Disease: A Systematic Review and Meta-Analysis

BACKGROUND

Psychotic symptoms are highly frequent in Parkinson's disease (PD) patients and are associated with poor prognosis. They include hallucinations, delusions, and minor psychotic phenomena, including sense of presence, passage hallucinations, and illusions.

OBJECTIVE

To evaluate the frequency of psychosis in PD patients.

METHODS

A systematic review and meta-analysis of clinical trials, prospective and retrospective cohort studies, case-control studies, and cross-sectional studies reporting the frequency of psychosis, hallucinations, and delusions in PD.

RESULTS

Electronic database search wielded 3536 articles, an additional 91 were identified through citation chaining. Of these, 163 were fully inspected, 57 removed, and 106 included as relevant for neuropsychiatric events frequency, with 32 meeting our inclusion criteria (psychosis and/or specific psychotic phenomena). The pooled frequency of psychosis was 20.7% (95% CI 14.5 to 28.6; I2 = 94%, 15 studies; combined n = 2919). None of the pre-defined meta-regressions or subgroup analyses were statistically significant or helped explain the statistical heterogeneity. The pooled frequency of any form of hallucination was 21.6% (95% CI 14.7 to 30.6; I2 = 95%; 18 studies; combined n = 3161). Duration of PD at baseline and mean baseline Hoehn & Yahr stage helped explain the statistical heterogeneity in the meta-analysis of hallucinations.

CONCLUSION

Based on the available evidence, around a fifth of PD patients experience psychosis or hallucinations. The risk of developing hallucinations is likely moderated by the disease duration, Hoehn & Yahr stage, and the cognitive status.

Neuropsychiatric aspects of Parkinson disease psychopharmacology: Insights from circuit dynamics

Parkinson disease (PD) is a neurodegenerative disorder with a complex pathophysiology characterized by the progressive loss of dopaminergic neurons within the substantia nigra. Persons with PD experience several motoric and neuropsychiatric symptoms. Neuropsychiatric features of PD include depression, anxiety, psychosis, impulse control disorders, and apathy. In this chapter, we will utilize the National Institutes of Mental Health Research Domain Criteria (RDoC) to frame and integrate observations from two prevailing disease constructions: neurotransmitter anomalies and circuit physiology. When there is available evidence, we posit how unified translational observations may have clinical relevance and postulate importance outside of PD. Finally, we review the limited evidence available for pharmacologic management of these symptoms.

Pimavanserin for Parkinson's Disease psychosis: Effects stratified by baseline cognition and use of cognitive-enhancing medications

BACKGROUND

PD psychosis is often associated with cognitive impairment, including dementia, and involves dopaminergic, serotonergic, and cholinergic mechanisms.

OBJECTIVE

To evaluate the differential effect of the antipsychotic pimavanserin, a selective serotonin 2A receptor inverse agonist, in PD psychosis patients with versus without cognitive impairment and in those receiving versus not receiving cognitive-enhancing medications.

METHODS

Data from the pivotal randomized clinical trial of pimavanserin for PD psychosis were stratified by (1) screening MMSE score as cognitively impaired (21-24) versus unimpaired (≥25) and (2) concomitant use versus nonuse of cognitive-enhancing medications. The primary outcome measure was change in the PD-adapted Scale for the Assessment of Positive Symptoms.

RESULTS

Mean (pimavanserin vs. placebo) change from baseline was larger in the cognitively impaired (n = 50; -6.62 vs. -0.91; P = 0.002) versus the cognitively unimpaired (n = 135; -5.50 vs. -3.23; p = 0.046) group. The comparable change was -6.04 versus -2.18 (P = 0.012) and -5.66 versus -3.15 (P = 0.041) in patients treated (n = 69) and not treated (n = 116) with concomitant cognitive-enhancing medication. Pimavanserin was similarly tolerated across all cognitive groups with no additional safety concerns identified. Overall adverse event rates were comparable across the concomitant cognitive-enhancing medication groups; however, rates of serious adverse events and discontinuations attributed to adverse events were increased in patients taking cholinesterase inhibitors.

CONCLUSIONS

The antipsychotic effect of pimavanserin is robust in PD patients with cognitive impairment and may be enhanced by concomitant cognitive-enhancing medication use. Future prospective studies are needed to confirm these preliminary findings. © 2018 The Authors. Movement Disorders published by Wiley Periodicals, Inc. on behalf of International Parkinson and Movement Disorder Society.