Does Prefrontal Glutamate Index Cognitive Changes in Parkinson's Disease?

Introduction: Cognitive impairment is a highly prevalent non-motor feature of Parkinson's disease (PD). A better understanding of the underlying pathophysiology may help in identifying therapeutic targets to prevent or treat dementia. This study sought to identify metabolic alterations in the prefrontal cortex (PFC), a key region for cognitive functioning that has been implicated in cognitive dysfunction in PD. Methods: Proton Magnetic Resonance Spectroscopy was used to investigate metabolic changes in the PFC of a cohort of cognitively normal individuals without PD (CTL), as well as PD participants with either normal cognition (PD-NC), mild cognitive impairment (PD-MCI), or dementia (PDD). Ratios to Creatine (Cre) resonance were obtained for glutamate (Glu), glutamine and glutamate combined (Glx), N-acetylaspartate (NAA), myoinositol (mI), and total choline (Cho), and correlated with cognitive scores across multiple domains (executive function, learning and memory, language, attention, visuospatial function, and global cognition) administered to the PD participants only. Results: When individuals retain cognitive capabilities, the presence of Parkinson's disease does not create metabolic disturbances in the PFC. However, when cognitive symptoms are present, PFC Glu/Cre ratios decrease with significant differences between the PD-NC and PPD groups. In addition, Glu/Cre ratios and memory scores were marginally associated, but not after Bonferroni correction. Conclusion: These preliminary findings indicate that fluctuations in prefrontal glutamate may constitute a biomarker for the progression of cognitive impairments in PD. We caution for larger MRS investigations of carefully defined PD groups.

Are Established Embedded Performance Validity Test Cut-Offs Generalizable to Patients With Multiple Sclerosis?

OBJECTIVE: Data for the use of embedded performance validity tests (ePVTs) with multiple sclerosis (MS) patients are limited. The purpose of the current study was to determine whether ePVTs previously validated in other neurological samples perform similarly in an MS sample. METHODS: In this retrospective study, the prevalence of below-criterion responding at different cut-off scores was calculated for each ePVT of interest among patients with MS who passed a stand-alone PVT. RESULTS: Previously established PVT cut-offs generally demonstrated acceptable specificity when applied to our sample. However, the overall cognitive burden of the sample was limited relative to that observed in prior large-scale MS studies. CONCLUSION: The current study provides initial data regarding the performance of select ePVTs among an MS sample. Results indicate most previously validated cut-offs avoid excessive false positive errors in a predominantly relapsing remitting MS sample. Further validation among MS patients with more advanced disease is warranted.

Performance Validity Testing in Neuropsychology: Methods for Measurement Development and Maximizing Diagnostic Accuracy.

In the first column in this 2-part series, Performance Validity Testing in Neuropsychology: Scientific Basis and Clinical Application-A Brief Review, the authors introduced performance validity tests (PVTs) and their function, provided a justification for why they are necessary, traced their ongoing endorsement by neuropsychological organizations, and described how they are used and interpreted by ever increasing numbers of clinical neuropsychologists. To enhance readers' understanding of these measures, this second column briefly describes common detection strategies used in PVTs as well as the typical methods used to validate new PVTs and determine cut scores for valid/invalid determinations. We provide a discussion of the latest research demonstrating how neuropsychologists can combine multiple PVTs in a single battery to improve sensitivity/specificity to invalid responding. Finally, we discuss future directions for the research and application of PVTs.

Performance Validity Testing in Neuropsychology: Scientific Basis and Clinical Application-A Brief Review.

Performance validity testing refers to neuropsychologists' methodology for determining whether neuropsychological test performances completed in the course of an evaluation are valid (ie, the results of true neurocognitive function) or invalid (ie, overly impacted by the patient's effort/engagement in testing). This determination relies upon the use of either standalone tests designed for this sole purpose, or specific scores/indicators embedded within traditional neuropsychological measures that have demonstrated this utility. In response to a greater appreciation for the critical role that performance validity issues play in neuropsychological testing and the need to measure this variable to the best of our ability, the scientific base for performance validity testing has expanded greatly over the last 20 to 30 years. As such, the majority of current day neuropsychologists in the United States use a variety of measures for the purpose of performance validity testing as part of everyday forensic and clinical practice and address this issue directly in their evaluations. The following is the first article of a 2-part series that will address the evolution of performance validity testing in the field of neuropsychology, both in terms of the science as well as the clinical application of this measurement technique. The second article of this series will review performance validity tests in terms of methods for development of these measures, and maximizing of diagnostic accuracy.

Retirement and Activity Restrictions Following Concussion.

Sport-related concussion is prevalent at all levels of play. Increased attention from sports media and scientific and medical communities has prompted players and physicians to explore the long-term effects of concussion and ask the questions of when and how players should begin to mitigate their concussion risk. The authors evaluate their risks from the perspective of epidemiology, symptomatology, neuropsychological performance, and biomechanics. The authors propose that there is not a set number of concussions that necessitates retirement in athletes and, aside from a few absolute contraindications to return to collision sport, return to play should be an individualized process.

[Formula: see text]Official Position of the American Academy of Clinical Neuropsychology (AACN): Guidelines for Practicum Training in Clinical Neuropsychology.

Practical experience is central to the education and training of neuropsychologists, beginning in graduate school and extending through postdoctoral fellowship. However, historically, little attention has been given to the structure and requirements of practicum training in clinical neuropsychology. A working group of senior-level neuropsychologists, as well as a current postdoctoral fellow, all from a diverse range of settings (The AACN Practicum Guidelines Workgroup), was formed to propose guidelines for practicum training in clinical neuropsychology. The Workgroup reviewed relevant literature and sought input from professional organizations involved in education and training in neuropsychology. The proposed guidelines provide a definition of practicum training in clinical neuropsychology, detail entry and exit criteria across competencies relevant to practicum training in clinical neuropsychology, and discuss the relationship between doctoral training programs and practicum training sites. The proposed guidelines also provide a methodology for competency-based evaluation of clinical neuropsychology practicum trainees and outline characteristics and features that are integral to an effective training environment. Although the guidelines discussed below may not be implemented in their entirety across all clinical neuropsychology practicum training sites, they are consistent with the latest developments in competency-based education.

Mild traumatic brain injury in the occupational setting.

The evaluation and management of mild traumatic brain injury (mTBI) in the occupational setting may pose significant challenges for even the most-seasoned practitioner. Providers must simultaneously address the clinical management of mTBI and be familiar with the systematic and administrative requirements related to the management of injured workers with mTBI who are covered by workers' compensation insurance, including causation, return to work, and the potential of permanent impairment. Given the primarily subjective nature of many mTBI symptoms, an injured worker with a delayed recovery may raise the question, if not suspicion, of symptom magnification and secondary gain. This review discusses the evaluation and treatment of the injured worker with mTBI, and focuses on the medicolegal issues that are present in the workers' compensation system, especially the role of neuropsychological evaluations. Although significant differences exist regarding classification schema, for the purposes of this discussion, mTBI is used to encompass the terms concussion, postconcussive syndrome, and persistent postconcussive syndrome.