Genetic influence on microstructure integrity and motor progression in Parkinson's disease.

BACKGROUND: Up to 10 % of Parkinson's disease (PD) populations carry a genetic risk variant, which may not only increase one's chance of developing PD but also affect disease presentation and progression. We hypothesize motor impairment in genetic carriers of PD correlate to different patterns of microstructural changes over time. DESIGN/METHODS: Data were accessed from the Parkinson's Progression Markers Initiative (PPMI) project. Connectometry analyses were performed for GBA1+ PD, LRRK2+ PD, and sporadic PD correlating white matter structural changes, as measured by quantitative anisotropy (QA), with motor impairment, as measured by MDS-UPDRS III. RESULTS: There was a negative correlation between QA and MDS-UPDRS III in all 3 cohorts at 48 months. In GBA1+ PD (n = 12), the white matter tracts identified were cortical and subcortical, while in the LRRK2+ PD (n = 18) and sporadic PD (n = 45) cohorts white tracts identified were primarily subcortical and within the brainstem. CONCLUSIONS: Our findings highlight the association between motor symptom progrerssion and structural connectivity in individuals with GBA1+ PD, LRRK2+ PD, and sporadic PD. Due to the small sample size, larger studies are needed in the future to confirm the findings.

Pharmacological treatment of apathy in Lewy body disorders: A systematic review.

INTRODUCTION: There are no approved treatments for apathy, a frequent and incapacitating symptom in Parkinson's disease (PD) and dementia with Lewy bodies (DLB). We reviewed the literature on the pharmacological treatment of apathy in PD and DLB to inform practice and future research. METHOD: We searched PubMed and PsycINFO using the terms "apathy", "treatment", and "Parkinson" or "Lewy body (bodies)." The results were filtered for "clinical trials" and "case reports." We included articles if apathy was measured as an outcome measure, before and after treatment. References of included articles were also reviewed. RESULTS: The PD search identified 19 articles: 13 randomized control trials (RCTs), 4 open-label studies, 1 case series, and 1 case report. Apathy was the primary outcome in 11 out of 19 studies. A decrease in apathy ratings was seen in 14 of the 19 studies. Of these 14 studies, 9 investigated medications with some dopaminergic effect. Three investigated acetylcholinesterase inhibitors (AChEIs) and found benefit in improving apathy. The DLB search identified 4 articles: 1 RCT, 2 open-label studies, and 1 case series. All 4 studies demonstrated decreased apathy and investigated AChEIs. CONCLUSIONS: We identified 23 studies that assessed the pharmacological treatment of apathy. In PD, agents with dopaminergic activity were the most studied and appeared to have the most benefit. AChEIs also appeared to have benefit in both PD and DLB but were less studied. Future studies of apathy treatment would benefit from larger samples and standardized assessments of apathy to define study populations and endpoints.

Common variant rs356182 near SNCA defines a Parkinson's disease endophenotype.

OBJECTIVE: Parkinson's disease (PD) presents clinically with several motor subtypes that exhibit variable treatment response and prognosis. Here, we investigated genetic variants for their potential association with PD motor phenotype and progression. METHODS: We screened 10 SNPs, previously associated with PD risk, for association with tremor-dominant (TD) versus postural-instability gait disorder (PIGD) motor subtypes. SNPs that correlated with the TD/PIGD ratio in a discovery cohort of 251 PD patients were then evaluated in a multi-site replication cohort of 559 PD patients. SNPs associated with motor phenotype in both cross-sectional cohorts were next evaluated for association with (1) rates of motor progression in a longitudinal subgroup of 230 PD patients and (2) brain alpha-synuclein (SNCA) expression in the GTEx (Genotype-Tissue Expression project) consortium database. RESULTS: Genotype at rs356182, near SNCA, correlated with the TD/PIGD ratio in both the discovery (Bonferroni-corrected P = 0.04) and replication cohorts (P = 0.02). The rs356182 GG genotype was associated with a more tremor-predominant phenotype and predicted a slower rate of motor progression (1-point difference in annual rate of UPDRS-III motor score change, P = 0.01). The rs356182 genotype was associated with SNCA expression in the cerebellum (P = 0.005). INTERPRETATION: Our study demonstrates that the GG genotype at rs356182 provides molecular definition for a clinically important endophenotype associated with (1) more tremor-predominant motor phenomenology, (2) slower rates of motor progression, and (3) decreased brain expression of SNCA. Such molecularly defined endophenotyping in PD may benefit both clinical trial design and tailoring of clinical care as we enter the era of precision medicine.

Biomarkers in Prodromal Parkinson Disease: a Qualitative Review.

BACKGROUND: Over the past several years, the concept of prodromal Parkinson disease (PD) has been increasingly recognized. This term refers to individuals who do not fulfill motor diagnostic criteria for PD, but who have clinical, genetic, or biomarker characteristics suggesting risk of developing PD in the future. Clinical diagnosis of prodromal PD has low specificity, prompting the need for objective biomarkers with higher specificity. In this qualitative review, we discuss objectively defined putative biomarkers for PD and prodromal PD. METHODS: We searched Pubmed and Embase for articles pertaining to objective biomarkers for PD and their application in prodromal cohorts. Articles were selected based on relevance and methodology. KEY FINDINGS: Objective biomarkers of demonstrated utility in prodromal PD include ligand-based imaging and transcranial sonography. Development of serum, cerebrospinal fluid, and tissue-based biomarkers is underway, but their application in prodromal PD has yet to meaningfully occur. Combining objective biomarkers with clinical or genetic prodromal features increases the sensitivity and specificity for identifying prodromal PD. CONCLUSIONS: Several objective biomarkers for prodromal PD show promise but require further study, including their application to and validation in prodromal cohorts followed longitudinally. Accurate identification of prodromal PD will likely require a multimodal approach. (JINS, 2016, 22, 956-967).

Prevalence of hypersexual behavior in Parkinson's disease patients: Not restricted to males and dopamine agonist use.

This study investigates the prevalence and demographic characteristics of hypersexuality in Parkinson's disease (PD). Impulse control disorders in PD patients have been associated with dopamine agonist therapy. Moreover, hypersexuality and pathological gambling have been associated with males, while females may be inherently thought to be more likely to participate in compulsive shopping and binge-eating behaviors. In this study, a screening mail-in survey was sent to all PD patients at a single Movement Disorders Center. One hundred forty one of 400 (35.3%) research packets were returned completed. Fifteen of 141 patients met initial screening criteria for hypersexual behavior. After detailed interview, only 6/141 (4.3%) of PD patients met criteria for pathologic hypersexual behavior. These behaviors included: compulsive masturbation, prostitution, and paraphilias. Patients with a younger age of PD onset were more likely to exhibit hypersexual behavior. Unlike previous report, no significant association was found between hypersexuality and gender or dopamine agonist use. Rather, this study suggests that physicians should be vigilant for hypersexual behavior in all PD patients, regardless of gender and PD medication regimen. Ultimately, given the innate sensitivity of the topic and survey limitations, it is very likely that hypersexual behavior in our cohort, as it is in the general PD population, has been under-reported.