Depression, intellectual impairment, and Parkinson disease

Neurovascular Mechanisms of Cognitive Aging: Sex-Related Differences in the Average Progression of Arteriosclerosis, White Matter Atrophy, and Cognitive Decline

Arterial stiffness (arteriosclerosis) has been linked to heightened risks for cognitive decline, and ultimately for Alzheimer's disease and other forms of dementia. Importantly, neurovascular outcomes generally vary according to one's biological sex. Here, capitalizing on a large sample of participants with neuroimaging and behavioral data ( N = 203, age range = 18-87 years), we aimed to provide support for a hierarchical model of neurocognitive aging, which links age-related declines in cerebrovascular health to the rate of cognitive decline via a series of intervening variables, such as white matter integrity. By applying a novel piecewise regression approach to our cross-sectional sample to support Granger-like causality inferences, we show that, on average, a precipitous decline in cerebral arterial elasticity (measured with diffuse optical imaging of the cerebral arterial pulse; pulse-DOT) temporally precedes an acceleration in the development of white matter lesions by nearly a decade, with women protected from these deleterious effects until approximately age 50, the average onset of menopause. By employing multiple-mediator path analyses while controlling for sex, we show that age may impair cognition via the sequential indirect effects of arteriosclerosis and white matter atrophy on fluid, but not crystallized, abilities. Importantly, we replicate these results using pulse pressure, an independent index of arterial health, thereby providing converging evidence for the central role of arteriosclerosis as an accelerating factor in normal and pathological aging and identifying robust sex-related differences in the progression of cerebral arteriosclerosis and white matter degradation.

Lab-made disposable screen-printed electrochemical sensors and immunosensors modified with Pd nanoparticles for Parkinson's disease diagnostics

A new conductive ink based on the addition of carbon black to a poly(vinyl alcohol) matrix is developed and investigated for electrochemical sensing and biosensing applications. The produced devices were characterized using morphological and electrochemical techniques and modified with Pd nanoparticles to enhance electrical conductivity and reaction kinetics. With the aid of chemometrics, the parameters for metal deposition were investigated and the sensor was applied to the determination of Parkinson's disease biomarkers, specifically epinephrine and α-synuclein. A linear behavior was obtained in the range 0.75 to 100 μmol L-1 of the neurotransmitter, and the device displayed a limit of detection (LOD) of 0.051 μmol L-1. The three-electrode system was then tested using samples of synthetic cerebrospinal fluid. Afterward, the device was modified with specific antibodies to quantify α-synuclein using electrochemical impedance spectroscopy. In phosphate buffer, a linear range was obtained for α-synuclein concentrations from 1.5 to 15 μg mL-1, with a calculated LOD of 0.13 μg mL-1. The proposed immunosensor was also applied to blood serum samples, and, in this case, the linear range was observed from 6.0 to 100.5 μg mL-1 of α-synuclein, with a LOD = 1.3 µg mL-1. Both linear curves attend the range for the real diagnosis, demonstrating its potential application to complex matrices.

The role of neurotransmitter systems in mediating deep brain stimulation effects in Parkinson’s disease

Deep brain stimulation (DBS) is among the most successful paradigms in both translational and reverse translational neuroscience. DBS has developed into a standard treatment for movement disorders such as Parkinson’s disease (PD) in recent decades, however, specific mechanisms behind DBS’s efficacy and side effects remain unrevealed. Several hypotheses have been proposed, including neuronal firing rate and pattern theories that emphasize the impact of DBS on local circuitry but detail distant electrophysiological readouts to a lesser extent. Furthermore, ample preclinical and clinical evidence indicates that DBS influences neurotransmitter dynamics in PD, particularly the effects of subthalamic nucleus (STN) DBS on striatal dopaminergic and glutamatergic systems; pallidum DBS on striatal dopaminergic and GABAergic systems; pedunculopontine nucleus DBS on cholinergic systems; and STN-DBS on locus coeruleus (LC) noradrenergic system. DBS has additionally been associated with mood-related side effects within brainstem serotoninergic systems in response to STN-DBS. Still, addressing the mechanisms of DBS on neurotransmitters’ dynamics is commonly overlooked due to its practical difficulties in monitoring real-time changes in remote areas. Given that electrical stimulation alters neurotransmitter release in local and remote regions, it eventually exhibits changes in specific neuronal functions. Consequently, such changes lead to further modulation, synthesis, and release of neurotransmitters. This narrative review discusses the main neurotransmitter dynamics in PD and their role in mediating DBS effects from preclinical and clinical data.

Phenomenology of Atypical Anxiety Disorders in Parkinson's Disease: A Systematic Review

OBJECTIVE

Anxiety is a prominent concern in Parkinson's disease (PD) that negatively impacts quality of life, increases functional disability, and complicates clinical management. Atypical presentations of anxiety are under-recognized and inadequately treated in patients with PD, compromising global PD care.

METHODS

This systematic review focuses on the prevalence, symptomology and clinical correlates of atypical presentations of PD-related anxiety following PRISMA guidelines.

RESULTS

Of the 60 studies meeting inclusion criteria, 14 focused on 'Anxiety Not Otherwise Specified (NOS)' or equivalent, 31 reported on fluctuating anxiety symptoms, and 22 reported on 'Fear of Falling (FOF)'. Anxiety NOS accounted for a weighted mean prevalence of 14.9%, fluctuating anxiety for 34.19%, and FOF for 51.5%. These latter two exceeded the average reported overall prevalence rate of 31% for anxiety disorders in PD. We identified a diverse array of anxiety symptoms related to motor and non-motor symptoms of PD, to complications of PD medication (such as "on" and "off" fluctuations, or both), and, to a lesser extent, to cognitive symptoms.

CONCLUSION

Atypical anxiety is common, clinically relevant, and heterogeneous in nature. A better understanding of the phenomenology, clinical course, and pathophysiology of varied forms of atypical anxiety in PD is needed to improve recognition, advance therapeutic development and ultimately optimize quality of life in PD.

Depression in Patients with Parkinson's Disease: Current Understanding of its Neurobiology and Implications for Treatment

Depression is one of the most frequent and burdensome non-motor symptoms in Parkinson’s disease (PD), across all stages. Even when its severity is mild, PD depression has a great impact on quality of life for these patients and their caregivers. Accordingly, accurate diagnosis, supported by validated scales, identification of risk factors, and recognition of motor and non-motor symptoms comorbid to depression are critical to understanding the neurobiology of depression, which in turn determines the effectiveness of dopaminergic drugs, antidepressants and non-pharmacological interventions. Recent advances using in vivo functional and structural imaging demonstrate that PD depression is underpinned by dysfunction of limbic networks and monoaminergic systems, depending on the stage of PD and its associated symptoms, including apathy, anxiety, rapid eye movement sleep behavior disorder (RBD), cognitive impairment and dementia. In particular, the evolution of serotonergic, noradrenergic, and dopaminergic dysfunction and abnormalities of limbic circuits across time, involving the anterior cingulate and orbitofrontal cortices, amygdala, thalamus and ventral striatum, help to delineate the variable expression of depression in patients with prodromal, early and advanced PD. Evidence is accumulating to support the use of dual serotonin and noradrenaline reuptake inhibitors (desipramine, nortriptyline, venlafaxine) in patients with PD and moderate to severe depression, while selective serotonin reuptake inhibitors, repetitive transcranial magnetic stimulation and cognitive behavioral therapy may also be considered. In all patients, recent findings advocate that optimization of dopamine replacement therapy and evaluation of deep brain stimulation of the subthalamic nucleus to improve motor symptoms represents an important first step, in addition to physical activity. Overall, this review indicates that increasing understanding of neurobiological changes help to implement a roadmap of tailored interventions for patients with PD and depression, depending on the stage and comorbid symptoms underlying PD subtypes and their prognosis.

Validation and demonstration of a new comprehensive model of Alzheimer's disease progression

INTRODUCTION

Identifying the course of Alzheimer's disease (AD) for individual patients is important for numerous clinical applications. Ideally, prognostic models should provide information about a range of clinical features across the entire disease process. Previously, we published a new comprehensive longitudinal model of AD progression with inputs/outputs covering 11 interconnected clinical measurement domains.

METHODS

Here, we (1) validate the model on an independent cohort; and (2) demonstrate the model's utility in clinical applications by projecting changes in 6 of the 11 domains.

RESULTS

Survival and prevalence curves for two representative outcomes-mortality and dependency-generated by the model accurately reproduced the observed curves both overall and for patients subdivided according to risk levels using an independent Cox model.

DISCUSSION

The new model, validated here, effectively reproduces the observed course of AD from an initial visit assessment, allowing users to project coordinated developments for individual patients of multiple disease features.

Antidepressant-Like Properties of Intrastriatal Botulinum Neurotoxin-A Injection in a Unilateral 6-OHDA Rat Model of Parkinson's Disease

Parkinson’s patients often suffer from depression and anxiety, for which there are no optimal treatments. Hemiparkinsonian (hemi-PD) rats were used to test whether intrastriatal Botulinum neurotoxin-A (BoNT-A) application could also have antidepressant-like properties in addition to the known improvement of motor performance. To quantify depression- and anxiety-like behavior, the forced swim test, tail suspension test, open field test, and elevated plus maze test were applied to hemi-PD rats injected with BoNT-A or vehicle. Furthermore, we correlated the results in the forced swim test, open field test, and elevated plus maze test with the rotational behavior induced by apomorphine and amphetamine. Hemi-PD rats did not show significant anxiety-like behavior as compared with Sham 6-OHDA- + Sham BoNT-A-injected as well as with non-injected rats. However, hemi-PD rats demonstrated increased depression-like behaviors compared with Sham- or non-injected rats; this was seen by increased struggling frequency and increased immobility frequency. Hemi-PD rats intrastriatally injected with BoNT-A exhibited reduced depression-like behavior compared with the respective vehicle-receiving hemi-PD animals. The significant effects of intrastriatally applied BoNT-A seen in the forced swim test are reminiscent of those found after various antidepressant drug therapies. Our data correspond with the efficacy of BoNT-A treatment of glabellar frown lines in treating patients with major depression and suggest that also intrastriatal injected BoNT-A may have some antidepressant-like effect on hemi-PD.

Attenuated dopamine signaling after aversive learning is restored by ketamine to rescue escape actions

Escaping aversive stimuli is essential for complex organisms, but prolonged exposure to stress leads to maladaptive learning. Stress alters neuronal activity and neuromodulatory signaling in distributed networks, modifying behavior. Here, we describe changes in dopaminergic neuron activity and signaling following aversive learning in a learned helplessness paradigm in mice. A single dose of ketamine suffices to restore escape behavior after aversive learning. Dopaminergic neuron activity in the ventral tegmental area (VTA) systematically varies across learning, correlating with future sensitivity to ketamine treatment. Ketamine’s effects are blocked by chemogenetic inhibition of dopamine signaling. Rather than directly altering the activity of dopaminergic neurons, ketamine appears to rescue dopamine dynamics through actions in the medial prefrontal cortex (mPFC). Chemogenetic activation of Drd1 receptor positive mPFC neurons mimics ketamine’s effects on behavior. Together, our data link neuromodulatory dynamics in mPFC-VTA circuits, aversive learning, and the effects of ketamine.

Over 264 million people around the world suffer from depression, according to the World Health Organization (WHO). Depression can be debilitating, and while anti-depressant drugs are available, they do not always work. A small molecule drug mainly used for anesthesia called ketamine has recently been shown to ameliorate depressive symptoms within hours, much faster than most anti-depressants. However, the molecular mechanisms behind this effect are still largely unknown.

Most anti-depressant drugs work by restoring the normal balance of dopamine and other chemical messengers in the brain. Dopamine is released by a specialized group of cells called dopaminergic neurons, and helps us make decisions by influencing a wide range of other cells in the brain. In a healthy brain, dopamine directs us to rewarding choices, while avoiding actions with negative outcomes. During depression, these dopamine signals are perturbed, resulting in reduced motivation and pleasure. But it remained unclear whether ketamine’s anti-depressant activity also relied on dopamine.

To investigate this, Wu et al. used a behavioral study called “learned helplessness” which simulates depression by putting mice in unavoidable stressful situations. Over time the mice learn that their actions do not change the outcome and eventually stop trying to escape from unpleasant situations, even if they are avoidable. The experiment showed that dopaminergic neurons in an area of the brain that is an important part of the “reward and aversion” system became less sensitive to unpleasant stimuli following learned helplessness. When the mice received ketamine, these neurons recovered after a few hours.

Individual mice also responded differently to ketamine. The most ‘resilient’, stress-resistant mice, which had distinct patterns of dopamine signaling, also responded most strongly to the drug. Genetic and chemical manipulation of dopaminergic neurons confirmed that ketamine needed intact dopamine signals to work, and revealed that it acted indirectly on dopamine dynamics via another brain region called the medial prefrontal cortex.

These results shed new light on how a promising new anti-depressant works. In the future, they may also explain why drugs like ketamine work better for some people than others, ultimately helping clinicians select the most effective treatment for individual patients.

Screen Fast, Screen Faster: A Pilot Study to Screen for Depressive Symptoms Using the Beck Depression Inventory Fast Screen in Parkinson's Disease With Mild Cognitive Impairment

Objective: Depressive symptoms have a high prevalence in patients with Parkinson's disease (PD) and are associated with cognitive dysfunction. Especially in PD with mild cognitive impairment (MCI), a time-efficient and valid instrument for the assessment of depression primarily focusing on psychological symptoms and disregarding confounding somatic symptoms is needed. We performed an examination of the psychometric properties of the Beck Depression Inventory II (BDI-II) and the Beck Depression Inventory Fast Screen (BDI-FS). Methods: The sample consisted of 64 patients [22 females and 42 males, mean age: 67.27 years (SD = 7.32)]. Depressive symptoms were measured in a cohort of PD patients with MCI. For the BDI-II and BDI-FS the psychometric concepts of internal consistency, convergent validity and diagnostic agreement were assessed. Results: Patients gave higher ratings on test items addressing somatic symptoms than those addressing non-somatic ones. The correlation between the absolute total scores of the BDI-II and the BDI-FS was significant (r = 0.91, p < 0.001), which indicated convergent validity. The Cronbach's alpha values indicated adequate internal consistencies for both measures (BDI-II: 0.84; BDI-FS: 0.78). There was a higher than chance level agreement of diagnoses of the two questionnaires, measured by Cohen's kappa (0.58, p < 0.001). The agreements between previous diagnosis of depression and the diagnoses of the BDI-II/BDI-FS were also significantly higher than chance level (BDI-II: 0.34, p = 0.007, BDI-FS: 0.39, p = 0.002). Additional AUC analysis across different cutoffs showed that performance of BDI-FS was better than BDI-II, supporting the observation of an equivalent or better performance of BDI-FS than BDI-II. Importantly, AUC analysis confirmed that a cutoff = 4 for BDI-FS was suitable in the considered sample of patients with PD-MCI. Discussion: In a cohort of PD-MCI, the BDI-FS demonstrates adequate psychometric properties in comparison to the BDI-II and can be used as a screening measure for assessing depression in cognitively impaired PD patients, focusing solely on psychological symptoms. Still, further research is needed to validate this instrument.

Spontaneous Alpha and Theta Oscillations Are Related to Complementary Aspects of Cognitive Control in Younger and Older Adults

The resting-state human electroencephalogram (EEG) power spectrum is dominated by alpha (8-12 Hz) and theta (4-8 Hz) oscillations, and also includes non-oscillatory broadband activity inversely related to frequency (1/f activity). Gratton proposed that alpha and theta oscillations are both related to cognitive control function, though in a complementary manner. Alpha activity is hypothesized to facilitate the maintenance of representations, such as task sets in preparation for expected task conditions. In contrast, theta activity would facilitate changes in representations, such as the updating of task sets in response to unpredicted task demands. Therefore, theta should be related to reactive control (which may prompt changes in task representations), while alpha may be more relevant to proactive control (which implies the maintenance of current task representations). Less is known about the possible relationship between 1/f activity and cognitive control, which was analyzed here in an exploratory fashion. To investigate these hypothesized relationships, we recorded eyes-open and eyes-closed resting-state EEG from younger and older adults and subsequently tested their performance on a cued flanker task, expected to elicit both proactive and reactive control processes. Results showed that alpha power and 1/f offset were smaller in older than younger adults, whereas theta power did not show age-related reductions. Resting alpha power and 1/f offset were associated with proactive control processes, whereas theta power was related to reactive control as measured by the cued flanker task. All associations were present over and above the effect of age, suggesting that these resting-state EEG correlates could be indicative of trait-like individual differences in cognitive control performance, which may be already evident in younger adults, and are still similarly present in healthy older adults.

Understanding the role of configural processing in face emotion recognition in Parkinson's disease

This investigation examined whether impairment in configural processing could explain deficits in face emotion recognition in people with Parkinson's disease (PD). Stimuli from the Radboud Faces Database were used to compare recognition of four negative emotion expressions by older adults with PD (n = 16) and matched controls (n = 17). Participants were tasked with categorizing emotional expressions from upright and inverted whole faces and facial composites; it is difficult to derive configural information from these two types of stimuli so featural processing should play a larger than usual role in accurate recognition of emotional expressions. We found that the PD group were impaired relative to controls in recognizing anger, disgust and fearful expressions in upright faces. Then, consistent with a configural processing deficit, participants with PD showed no composite effect when attempting to identify facial expressions of anger, disgust and fear. A face inversion effect, however, was observed in the performance of all participants in both the whole faces and facial composites tasks. These findings can be explained in terms of a configural processing deficit if it is assumed that the disruption caused by facial composites was specific to configural processing, whereas inversion reduced performance by making it difficult to derive both featural and configural information from faces.

Stimulation-induced side effects after deep brain stimulation - a systematic review

OBJECTIVE

Deep brain stimulation (DBS) was approved by Food and Drug Administration for Parkinson's disease, essential tremor, primary generalised or segmental dystonia and obsessive-compulsive disorder (OCD) treatment. The exact mechanism of DBS remains unclear which causes side effects. The aim of this review was to assess variables causing stimulation-induced chronic psychiatric/personality-changing side effects.

METHODS

The analysis of scientific database (PubMed, Cochrane Library, EMBASE) was conducted. The included articles had to be research study or case report and DBS to be conducted in therapeutic purposes. The researches with mental disorders in patients' medical histories were excluded.

RESULTS

Seventeen articles were used in the review. In the group of movement disorders the characteristic of side effects was strongly related to the placement of the electrode implantation. Tiredness/fatigue was correlated with DBS in thalamus. Implantations in subthalamic nucleus were mostly followed by affective side effects such as depression or suicide. The higher voltage of electrode was connected with more severe depression after implantation. The analysis of affective disorder contained only three articles - two about OCD and one about depression. Forgetfulness and word-finding problems as activities connected with cognition may be an inevitable side effect if obsessive thoughts are to be inhibited.

CONCLUSION

DBS of subthalamic nucleus should be seen as the most hazardous place of implantation. As a result there is a strong need of 'gold standards' based on the connectivity research and closer cooperation of scientists and clinicians.

Age-related differences in functional brain network segregation are consistent with a cascade of cerebrovascular, structural, and cognitive effects

Age-related declines in cognition are associated with widespread structural and functional brain changes, including changes in resting-state functional connectivity and gray and white matter status. Recently we have shown that the elasticity of cerebral arteries also explains some of the variance in cognitive and brain health in aging. Here, we investigated how network segregation, cerebral arterial elasticity (measured with pulse-DOT-the arterial pulse based on diffuse optical tomography) and gray and white matter status jointly account for age-related differences in cognitive performance. We hypothesized that at least some of the variance in brain and cognitive aging is linked to reduced cerebrovascular elasticity, leading to increased cortical atrophy and white matter abnormalities, which, in turn, are linked to reduced network segregation and decreases in cognitive performance. Pairwise comparisons between these variables are consistent with an exploratory hierarchical model linking them, especially when focusing on association network segregation (compared with segregation in sensorimotor networks). These findings suggest that preventing or slowing age-related changes in one or more of these factors may induce a neurophysiological cascade beneficial for preserving cognition in aging.

Optical measures of cerebral arterial stiffness are associated with white matter signal abnormalities and cognitive performance in normal aging

Decline in fluid abilities in normal aging is associated with increased white matter lesions, measured on T1-weighted images as white matter signal abnormalities (WMSAs). WMSAs are particularly evident in hypertensive older adults, suggesting vascular involvement. However, because hypertension is assessed systemically, the specific role of cerebral arterial stiffening in WMSAs has yet to be demonstrated. In 93 cognitively normal adults (aged 18-87 years), we used a novel method to measure cerebral arterial elasticity (pulse relaxation function [PReFx]) with diffuse optical tomography (pulse-DOT) and investigated its association with WMSAs, age, and cognition. PReFx was associated with WMSAs, with older adults with low PReFx showing the greatest WMSA burden. PReFx in brain regions perfused by the middle cerebral artery showed the largest associations with WMSAs and partially mediated the relationship between age and WMSAs. Finally, WMSAs partially mediated the relationship between PReFx and fluid but not crystallized abilities scores. Taken together, these findings suggest that loss of cerebral arterial elasticity is associated with cerebral white matter lesions and age-related cognitive decline.

The Optical Effective Attenuation Coefficient as an Informative Measure of Brain Health in Aging

Aging is accompanied by widespread changes in brain tissue. Here, we hypothesized that head tissue opacity to near-infrared light provides information about the health status of the brain’s cortical mantle. In diffusive media such as the head, opacity is quantified through the Effective Attenuation Coefficient (EAC), which is proportional to the geometric mean of the absorption and reduced scattering coefficients. EAC is estimated by the slope of the relationship between source–detector distance and the logarithm of the amount of light reaching the detector (optical density). We obtained EAC maps across the head in 47 adults (age range 18–75 years), using a high-density dual-wavelength optical system. We correlated regional and global EAC measures with demographic, neuropsychological, structural and functional brain data. Results indicated that EAC values averaged across wavelengths were strongly associated with age-related changes in cortical thickness, as well as functional and neuropsychological measures. This is likely because the EAC largely depends on the thickness of the sub-arachnoid cerebrospinal fluid layer, which increases with cortical atrophy. In addition, differences in EAC values between wavelengths were correlated with tissue oxygenation and cardiorespiratory fitness, indicating that information about cortical health can be derived non-invasively by quantifying the EAC.

Cognitive Functional Abilities in Parkinson's Disease: Agreement Between Patients and Informants

BACKGROUND

The Penn Parkinson's Daily Activities Questionnaire-15 (PDAQ-15) assesses cognition-related instrumental activities of daily living (IADL) in Parkinson's disease (PD).

OBJECTIVES

To assess the degree and predictors of disagreement between patients (PT) and knowledgeable informants (KI) on the PDAQ-15.

METHODS

We recruited 254 PT and KI pairs (PT-KI), determined predictors of agreement, and compared scores to a performance-based functional measure (Direct Assessment of Functional Status [DAFS]; N = 61).

RESULTS

PT and KI total score (intraclass correlation = 0.57) and individual item (Cohen's kappa = 0.46-0.62) agreement were moderate. Patient depression, global cognition, and caregiver burden (all P < 0.05), predicted PT-KI discrepancy. PT-KI discrepancy was highest in patients with a dementia diagnosis, followed by mild cognitive impairment and then normal cognition (all P < 0.01), with PT rating themselves relatively more functionally intact as cognition worsened. DAFS performance was more highly correlated with KI (r = 0.82; P < 0.001) than PT (r = 0.62; P < 0.001) PDAQ-15 score.

CONCLUSIONS

Our results support using KI as proxies when assessing cognitive IADLs in PD PTs, particularly in cases of more advanced cognitive decline.

Depression et Maladie de Parkinson: étude d’une série de 135 parkinsoniens

Objective:

La fréquence de la dépression au cours de la maladie de Parkinson (MP) conduit à s’interroger sur les difficultés du diagnostic et sur les liens entre la dépression et l’histoire naturelle de la maladie.

Méthodes:

Une série consécutive de 135 sujets atteints d’une MPidiopathique a été examinée sur le plan psychiatrique (DSM-III-R, échelle de dépression de Goldberg), neurologique (en distinguant les signes “axiaux” des autres signes parkinsoniens), neuropsychologique ( et en particulier tests frontaux).

Résultats:

Plus de la moitié des sujets ont une dépression qui apparaît plus fréquente dans les formes akinétiques et les formes fluctuantes de la maladie. Les sujets déprimés n’ont pas de déficit cognitif plus marqué mais leurs scores aux tests frontaux sont plus élevés. En outre les signes axiaux de la maladie (instabilité posturale, rigidité axiale) sont plus marqués chez les parkinsoniens déprimés, suggérant un lien entre la dépression et les lésions non dopaminergiques de la maladie. Alors que le ralentissement, les troubles de l’appétit et du sommeil, la fatigue peuvent être observés même chez des parkinsoniens non dépressifs, la séparation de la population parkinsonienne en plusieurs groupes montre que certains symptômes ne sont jamais rencontrés chez les parkinsoniens non dépressifs: il en est ainsi apparu que “l’impression que la vie ne vaut pas la peine d’être vécue”, “la perte d’espoir pour l’avenir”, “l’impression de ne pas être à la hauteur, de ne rien faire de bien”, “la baisse d’énergie”, “la tristesse matinale” caractérisent la dépression parkinsonienne. La dépression parkinsonienne revêt deux grandes formes cliniques. La première est la plus riche en manifestations somatiques: troubles du sommeil, fatigue matinale; elle correspond aux dépressions les plus sévères avec une absence d’espoir pour l’avenir , une perte de confiance en soi. La seconde est pauvre en manifestations somatiques alors que l’apathie y est très fréquente ainsi que le ralentissement.

Conclusions:

Cette étude permet ainsi de préciser les symptômes de la dépression parkinsonienne qui doit être mieux reconnue pour être plus souvent traitée. Les liens entre la dépression et les signes axiaux de la maladie expliquent sans doute pourquoi la L-dopa et les agonistes dopaminergiques améliorent les signes moteurs de la dépression sans agir le plus souvent sur les manifestations dépressives.

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.

Cognitive and Neuropsychiatric Features of Early Parkinson's Disease

The clinical definition of Parkinson's disease (PD) is based on cardinal motor features including bradykinesia as well as an additional symptom of tremor, postural instability, or rigidity. Evidence from neuropathological, imaging, and clinical research suggests a premotor, early phase of PD pathology. Further understanding of the earliest biomarkers of PD is crucial for the development of neuroprotective, disease modifying, cognitive, and psychiatric interventions. Recent research has explored early non-motor markers of PD pathology. This issue is especially timely as the International Parkinson and Movement Disorder Society has recently provided a research definition for prodromal PD which includes combinations of prodromal markers and risk factors aimed at identifying target populations for disease-prevention trials. In this review of early PD, we will outline early non-motor symptoms, early cognitive and neuropsychiatric features, neuropsychological assessment strategies, emerging evidence for early biomarkers, and treatment recommendations.

Individual differences in regional cortical volumes across the life span are associated with regional optical measures of arterial elasticity

Aging is often accompanied by changes in brain anatomy and cerebrovascular health. However, the specific relationship between declines in regional cortical volumes and loss of cerebral arterial elasticity is less clear, as only global or very localized estimates of cerebrovascular health have been available. Here we employed a novel tomographic optical method (pulse-DOT) to derive local estimates of cerebral arterial elasticity and compared regional volumetric estimates (obtained with FreeSurfer) with optical arterial elasticity estimates from the same regions in 47 healthy adults (aged 18-75). Between-subject analyses revealed a global correlation between cortical volume and cortical arterial elasticity, which was a significant mediator of the association between age and cortical volume. Crucially, a novel within-subject analysis highlighted the spatial association between regional variability in cortical volumes and arterial elasticity in the same regions. This association strengthened with age. Gains in the predictability of cortical volumes from arterial elasticity data were obtained by sharpening the resolution up to individual cortical regions. These results indicate that some of the variance of sub-clinical age-related brain atrophy is associated with differences in the status of cerebral arteries, and can help explain the unique patterns of brain atrophy found within each individual.

Support System to Improve Reading Activity in Parkinson's Disease and Essential Tremor Patients

The use of information and communication technologies (ICTs) to improve the quality of life of people with chronic and degenerative diseases is a topic receiving much attention nowadays. We can observe that new technologies have driven numerous scientific projects in e-Health, encompassing Smart and Mobile Health, in order to address all the matters related to data processing and health. Our work focuses on helping to improve the quality of life of people with Parkinson’s Disease (PD) and Essential Tremor (ET) by means of a low-cost platform that enables them to read books in an easy manner. Our system is composed of two robotic arms and a graphical interface developed for Android platforms. After several tests, our proposal has achieved a 96.5% accuracy for A4 80 gr non-glossy paper. Moreover, our system has outperformed the state-of-the-art platforms considering different types of paper and inclined surfaces. The feedback from ET and PD patients was collected at “La Princesa” University Hospital in Madrid and was used to study the user experience. Several features such as ease of use, speed, correct behavior or confidence were measured via patient feedback, and a high level of satisfaction was awarded to most of them. According to the patients, our system is a promising tool for facilitating the activity of reading.

Mapping cerebral pulse pressure and arterial compliance over the adult lifespan with optical imaging

Cerebrovascular health is important for maintaining a high level of cognitive performance, not only in old age, but also throughout the lifespan. Recently, it was first demonstrated that diffuse optical imaging measures of pulse amplitude and arterial compliance can provide estimates of cerebral arterial health throughout the cortex, and were associated with age, estimated cardiorespiratory fitness (eCRF), neuroanatomy and cognitive function in older adults (aged 55-87). The current study replicates and extends the original findings using a broader age range (a new adult sample aged 18-75), longer recording periods (360 s), and a more extensive optical montage (1536 channels). These methodological improvements represent a 5-fold increase in recording time and a 4-fold increase in coverage compared to the initial study. Results show that reliability for both pulse amplitude and compliance measures across recording blocks was very high (r(45) = .99 and .75, respectively). Pulse amplitude and pulse pressure were shown to correlate with age across the broader age range. We also found correlations between arterial health and both cortical and subcortical gray matter volumes. Additionally, we replicated the correlations between arterial compliance and age, eCRF, global brain atrophy, and cognitive flexibility. New regional analyses revealed that higher performance on the operation span (OSPAN) working memory task was associated with greater localized arterial compliance in frontoparietal cortex, but not with global arterial compliance. Further, greater arterial compliance in frontoparietal regions was associated with younger age and higher eCRF. These associations were not present in the visual cortex. The current study not only replicates the initial one in a sample including a much wider age range, but also provides new evidence showing that frontoparietal regions may be especially vulnerable to vascular degeneration during brain aging, with potential functional consequences in cognition.

Bitemporal v. high-dose right unilateral electroconvulsive therapy for depression: a systematic review and meta-analysis of randomized controlled trials

BACKGROUND

Brief-pulse electroconvulsive therapy (ECT) is the most acutely effective treatment for severe depression though concerns persist about cognitive side-effects. While bitemporal electrode placement is the most commonly used form worldwide, right unilateral ECT causes less cognitive side-effects though historically it has been deemed less effective. Several randomized trials have now compared high-dose (>5× seizure threshold) unilateral ECT with moderate-dose (1.0-2.5× seizure threshold) bitemporal ECT to investigate if it is as effective as bitemporal ECT but still has less cognitive side-effects. We aimed to systematically review these trials and meta-analyse clinical and cognitive outcomes where appropriate.

METHOD

We searched PubMed, PsycINFO, Web of Science, Cochrane Library and EMBASE for randomized trials comparing these forms of ECT using the terms 'electroconvulsive' OR 'electroshock' AND 'trial'.

RESULTS

Seven trials (n = 792) met inclusion criteria. Bitemporal ECT did not differ from high-dose unilateral ECT on depression rating change scores [Hedges's g = -0.03, 95% confidence interval (CI) -0.17 to 0.11], remission (RR 1.06, 95% CI 0.93-1.20), or relapse at 12 months (RR 1.42, 95% CI 0.90-2.23). There was an advantage for unilateral ECT on reorientation time after individual ECT sessions (mean difference in minutes = -8.28, 95% CI -12.86 to -3.70) and retrograde autobiographical memory (Hedges's g = -0.46, 95% CI -0.87 to -0.04) after completing an ECT course. There were no differences for general cognition, category fluency and delayed visual and verbal memory.

CONCLUSIONS

High-dose unilateral ECT does not differ from moderate-dose bitemporal ECT in antidepressant efficacy but has some cognitive advantages.

Optical measures of changes in cerebral vascular tone during voluntary breath holding and a Sternberg memory task

The human cerebral vasculature responds to changes in blood pressure and demands for oxygenation via cerebral autoregulation. Changes in cerebrovascular tone (vasoconstriction and vasodilation) also mediate the changes in blood flow measured by the BOLD fMRI signal. This cerebrovascular reactivity is known to vary with age. In two experiments, we demonstrate that cerebral pulse parameters measured using optical imaging can quantify changes in cerebral vascular tone, both globally and locally. In experiment 1, 51 older adults (age range=55-87) performed a voluntary breath-holding task while cerebral pulse amplitude measures were taken. We found significant pulse amplitude variations across breath-holding periods, indicating vasodilation during, and vasoconstriction after breath holding. The breath-holding index (BHI), a measure of cerebrovascular reactivity (CVR) was derived and found to correlate with age. BHI was also correlated with performance in the Modified Mini-Mental Status Examination, even after controlling for age and education. In experiment 2, the same participants performed a Sternberg task, and changes in regional pulse amplitude between high (set-size 6) and low (set-size 2) task loads were compared. Only task-related areas in the fronto-parietal network (FPN) showed significant reduction in pulse amplitude, indicating vasodilation. Non-task-related areas such as the somatosensory and auditory cortices did not show such reductions. Taken together, these experiments suggest that optical pulse parameters can index changes in brain vascular tone both globally and locally, using both physiological and cognitive load manipulations.

Comparing Aging and Fitness Effects on Brain Anatomy

Recent studies suggest that cardiorespiratory fitness (CRF) mitigates the brain’s atrophy typically associated with aging, via a variety of beneficial mechanisms. One could argue that if CRF is generally counteracting the negative effects of aging, the same regions that display the greatest age-related volumetric loss should also show the largest beneficial effects of fitness. To test this hypothesis we examined structural MRI data from 54 healthy older adults (ages 55–87), to determine the overlap, across brain regions, of the profiles of age and fitness effects. Results showed that lower fitness and older age are associated with atrophy in several brain regions, replicating past studies. However, when the profiles of age and fitness effects were compared using a number of statistical approaches, the effects were not entirely overlapping. Interestingly, some of the regions that were most influenced by age were among those not influenced by fitness. Presumably, the age-related atrophy occurring in these regions is due to factors that are more impervious to the beneficial effects of fitness. Possible mechanisms supporting regional heterogeneity may include differential involvement in motor function, the presence of adult neurogenesis, and differential sensitivity to cerebrovascular, neurotrophic and metabolic factors.

Brain Systems Underlying Susceptibility to Helplessness and Depression

There has been a relative lack of research into the neurobiological predispositions that confer vulnerability to depression. This article reviews functional brain mappings from a genetic animal model, the congenitally helpless rat, which is predisposed to develop learned helplessness. Neurometabolic findings from this model are integrated with the neuroscientific literature from other animal models of depression as well as depressed humans. Changes in four major brain systems are suggested to underlie susceptibility to helplessness and possibly depression: (a) an unbalanced prefrontal-cingulate cortical system, (b) a dissociated hypothalamic-pituitary-adrenal axis, (c) a dissociated septal-hippocampal system, and (d) a hypoactive brain reward system, as exemplified by a hypermetabolic habenula-interpeduncular nucleus pathway and a hypometabolic ventral tegmental area-striatum pathway. Functional interconnections and causal relationships among these systems are considered and further experiments are suggested, with theoretical attention to how an abnormality in any one system could affect the others.

Phonological Dyslexia

Following brain damage, skilled readers may encounter more severe problems in reading nonwords than familiar words, a type of deficit referred to as phonological dyslexia. We report on 2 individuals with Alzheimer's disease who show phonological dyslexia. Although highly accurate in reading familiar words aloud (even those with irregular spelling, such as sew), they were quite impaired in nonword reading. Both patients performed well in phonological tasks involving the repetition, identification, and manipulation of phonemes of orally presented words and nonwords. These results challenge the idea, proposed in the context of connectionist and evolutionary theories, that phonological dyslexia originates from a phonological deficit. However, the results are consistent with reading models, such as the dual-route model, that attribute phonological dyslexia to a deficit that selectively affects the reading mechanisms responsible for deriving the sounds of non-words. According to these models, such a deficit is not necessarily accompanied by a more general phonological impairment.

On Teaching Old Dogs New Tricks

Although older adults rarely outperform young adults on learning tasks, in the study reported here they surpassed their younger counterparts not only by answering more semantic-memory general-information questions correctly, but also by better correcting their mistakes. While both young and older adults exhibited a hypercorrection effect, correcting their high-confidence errors more than their low-confidence errors, the effect was larger for young adults. Whereas older adults corrected high-confidence errors to the same extent as did young adults, they outdid the young in also correcting their low-confidence errors. Their event-related potentials point to an attentional explanation: Both groups showed a strong attention-related P3a in conjunction with high-confidence-error feedback, but the older adults also showed strong P3as to low-confidence-error feedback. Indeed, the older adults were able to rally their attentional resources to learn the true answers regardless of their original confidence in the errors and regardless of their familiarity with the answers.

Behavioral impairments and serotonin reductions in rats after chronic L-dopa

RATIONALE

L-dopa, the main therapeutic for Parkinson's disease (PD), has been shown to increase brain dopamine concentrations that are necessary for proper motor control; however, PD patients experience non-motor symptoms that are not improved or could be exacerbated by L-dopa.

OBJECTIVES

The purpose of this study is to determine the effects of L-dopa treatment on cognitive and affective behavioral responses of rats, as well as their corresponding monoamine brain concentrations.

METHODS

Rats were treated with L-dopa (6 mg/kg; twice daily) for 10 consecutive days. Sodium ascorbate (400 mg/kg) was co-administered with L-dopa to investigate the effects of antioxidant co-treatment on behavior and monoamine concentrations. Rats underwent cognitive and affective behavioral testing. Monoamine concentrations of several brain regions were analyzed.

RESULTS

L-dopa treatment resulted in significant impairment in the performance in the Barnes maze and improvement in conditioned fear stress paradigms. Specifically, L-dopa caused an increase in latency to find the goal box during Barnes maze testing and increased freezing behavior in context-induced conditioned fear testing. Furthermore, the rats in the conditioned fear stress experiments showed corresponding depletions in serotonin (5-HT) and its metabolite, 5-HIAA, in the dorsal raphe nucleus (DRN) and the mPFC. The behavioral impairments as well as monoamine depletions were blocked by ascorbate co-treatment.

CONCLUSIONS

Chronic L-dopa may contribute to non-motor symptoms related to spatial memory and fear. These effects may be attributable to a dysregulation of brain 5-HT caused by L-dopa treatment. The results presented here provide further rationale for investigating adjunctive therapeutics to L-dopa for PD, such as antioxidants.

Nanotechnology-mediated nose to brain drug delivery for Parkinson's disease: a mini review

Nose to brain delivery of neurotherapeutics have been tried by several researchers to explore the virtues of this route viz. circumvention of BBB, avoidance of hepatic metabolism, practicality, safety, ease of administration and non-invasiveness. Nanoparticle (NP) therapeutics is an emerging modality for the treatment of Parkinson's disease (PD) as it offers targeted delivery and enhances the therapeutic efficacy and/or bioavailability of neurotherapeutics. This review presents a concise incursion into the nanomedicines suitable for PD therapy delivered via naso-brain transport. Clinical signs of PD, its pathophysiology, specific genetic determinants, diagnosis and therapy involved have been hashed out. Properties of brain-targeting NPs, transport efficacy and various nanocarriers developed so far also been furnished. In our opinion, nanotechnology-enabled naso-brain drug delivery is an excellent means of delivering neurotherapeutics and is a promising avenue for researchers to develop new formulations for the effective management of PD.

Depression in Parkinson's Disease

Objective:

To examine predictive factors associated with onset of depression among individuals diagnosed with Parkinson's disease (PD).

Background:

Depression may precede or follow symptomatic parkinsonism in PD. It is frequently treatable but often overlooked.

Methods:

The clinical series comprised 685 individuals who were diagnosed with PD and followed by one neurologist (RJU) from 1994 to 2007. The primary outcome was time to depression following the onset of PD. Diagnosis of depression was based on clinical assessment of depressive symptoms from patients (and spouse/family/caregiver) and antidepressant usage. A number of demographic, historical and clinical predictive factors were examined, including gender, age at symptomatic onset, disease duration, onset characteristics, clinical ratings, antiparkinsonian medications, cognitive status, depression history, and familial history of PD and other neurodegenerative disorders.

Results:

Seventy-two percent of patients developed depression within ten years of symptomatic PD onset, and the mean time to depression was 7.9 years (median: 5.7 years). Factors associated with depression included longer PD duration, greater impairment in activities of daily living, and positive family history of motor neuron disease (MND).

Conclusions:

A high rate of individuals with PD develop depressive symptoms during the course of the disease. Based on first clinic visit characteristics, most factors examined were not helpful in identifying individuals with an increased risk of depression. However, disease duration, functional limitations and family history of MND should lead clinicians to an increased vigilance for identifying depression.

Social cognition in Alzheimer's disease: a separate construct contributing to dependence

The extent to which social cognitive changes reflect a discrete constellation of symptoms dissociable from general cognitive changes in Alzheimer's disease (AD) is unclear. Moreover, whether social cognitive symptoms contribute to disease severity and progression is unknown. The current multicenter study investigated cross-sectional and longitudinal associations between social cognition measured with six items from the Blessed Dementia Rating Scale, general cognition, and dependence in 517 participants with probable AD. Participants were monitored every 6 months for 5.5 years. Results from multivariate latent growth curve models adjusted for sex, age, education, depression, and recruitment site revealed that social cognition and general cognition were unrelated cross-sectionally and throughout time. However, baseline levels of each were related independently to dependence, and change values of each were related independently to change in dependence. These findings highlight the separability of social and general cognition in AD. Results underscore the relevance of considering social cognition when modeling disease and estimating clinical outcomes related to patient disability.

Taking the pulse of aging: mapping pulse pressure and elasticity in cerebral arteries with optical methods

Cerebrovascular support is crucial for healthy cognitive and brain aging. Arterial stiffening is a cause of reduced brain blood flow, a predictor of cognitive decline, and a risk factor for cerebrovascular accidents and Alzheimer's disease. Arterial health is influenced by lifestyle factors, such as cardiorespiratory fitness (CRF). We investigated new noninvasive optical measures of cerebrovascular health, which provide estimates of arterial pulse parameters (pulse pressure, transit time, and compliance/elasticity) within specific cerebral arteries and cortical regions, and low-resolution maps of large superficial cerebral arteries. We studied naturally occurring variability in these parameters in adults (aged 55-87), and found that these indices of cerebrovascular health are negatively correlated with age and positively with CRF and gray and white matter volumes. Further, regional pulse transit time predicts specific neuropsychological performance.

Spread of activation and deactivation in the brain: does age matter?

Cross-sectional aging functional MRI results are sometimes difficult to interpret, as standard measures of activation and deactivation may confound variations in signal amplitude and spread, which however, may be differentially affected by age-related changes in various anatomical and physiological factors. To disentangle these two types of measures, here we propose a novel method to obtain independent estimates of the peak amplitude and spread of the BOLD signal in areas activated (task-positive) and deactivated (task-negative) by a Sternberg task, in 14 younger and 28 older adults. The peak measures indicated that, compared to younger adults, older adults had increased activation of the task-positive network, but similar levels of deactivation in the task-negative network. Measures of signal spread revealed that older adults had an increased spread of activation in task-positive areas, but a starkly reduced spread of deactivation in task-negative areas. These effects were consistent across regions within each network. Further, there was greater variability in the anatomical localization of peak points in older adults, leading to reduced cross-subject overlap. These results reveal factors that may confound the interpretation of studies of aging. Additionally, spread measures may be linked to local connectivity phenomena and could be particularly useful to analyze age-related deactivation patterns, complementing the results obtained with standard peak and region of interest analyses.

Cardiorespiratory fitness mediates the effects of aging on cerebral blood flow

The brain's vasculature is likely to be subjected to the same age-related physiological and anatomical changes affecting the rest of the cardiovascular system. Since aerobic fitness is known to alleviate both cognitive and volumetric losses in the brain, it is important to investigate some of the possible mechanisms underlying these beneficial changes. Here we investigated the role that estimated cardiorespiratory fitness (eCRF) plays in determining the relationship between aging and cerebral blood flow (CBF) in a group of older adults (ages 55–85). Using arterial spin labeling to quantify CBF, we found that blood flow in the gray matter was positively correlated with eCRF and negatively correlated with age. Subsequent analyses revealed that eCRF fully mediated the effects of age on CBF in the gray matter, but not in the white matter. Additionally, regional measures of CBF were related to regional measures of brain volume. These findings provide evidence that age-related effects on cerebrovascular health and perfusion in older adults are largely influenced by their eCRF levels.

Cholinergic dysfunction in Parkinson's disease

There is increasing interest in the clinical effects of cholinergic basal forebrain and tegmental pedunculopontine complex (PPN) projection degeneration in Parkinson's disease (PD). Recent evidence supports an expanded role beyond cognitive impairment, including effects on olfaction, mood, REM sleep behavior disorder, and motor functions. Cholinergic denervation is variable in PD without dementia and may contribute to clinical symptom heterogeneity. Early in vivo imaging evidence that impaired cholinergic integrity of the PPN associates with frequent falling in PD is now confirmed by human post-mortem evidence. Brainstem cholinergic lesioning studies in primates confirm the role of the PPN in mobility impairment. Degeneration of basal forebrain cholinergic projections correlates with decreased walking speed. Cumulatively, these findings provide evidence for a new paradigm to explain dopamine-resistant features of mobility impairments in PD. Recognition of the increased clinical role of cholinergic system degeneration may motivate new research to expand indications for cholinergic therapy in PD.

Neurovascular coupling in normal aging: a combined optical, ERP and fMRI study

Brain aging is characterized by changes in both hemodynamic and neuronal responses, which may be influenced by the cardiorespiratory fitness of the individual. To investigate the relationship between neuronal and hemodynamic changes, we studied the brain activity elicited by visual stimulation (checkerboard reversals at different frequencies) in younger adults and in older adults varying in physical fitness. Four functional brain measures were used to compare neuronal and hemodynamic responses obtained from BA17: two reflecting neuronal activity (the event-related optical signal, EROS, and the C1 response of the ERP), and two reflecting functional hemodynamic changes (functional magnetic resonance imaging, fMRI, and near-infrared spectroscopy, NIRS). The results indicated that both younger and older adults exhibited a quadratic relationship between neuronal and hemodynamic effects, with reduced increases of the hemodynamic response at high levels of neuronal activity. Although older adults showed reduced activation, similar neurovascular coupling functions were observed in the two age groups when fMRI and deoxy-hemoglobin measures were used. However, the coupling between oxy- and deoxy-hemoglobin changes decreased with age and increased with increasing fitness. These data indicate that departures from linearity in neurovascular coupling may be present when using hemodynamic measures to study neuronal function.

Neural and behavioral substrates of subtypes of Parkinson's disease

Parkinson’s disease (PD) is a neurological disorder, associated with rigidity, bradykinesia, and resting tremor, among other motor symptoms. In addition, patients with PD also show cognitive and psychiatric dysfunction, including dementia, mild cognitive impairment (MCI), depression, hallucinations, among others. Interestingly, the occurrence of these symptoms—motor, cognitive, and psychiatric—vary among individuals, such that a subgroup of PD patients might show some of the symptoms, but another subgroup does not. This has prompted neurologists and scientists to subtype PD patients depending on the severity of symptoms they show. Neural studies have also mapped different motor, cognitive, and psychiatric symptoms in PD to different brain networks. In this review, we discuss the neural and behavioral substrates of most common subtypes of PD patients, that are related to the occurrence of: (a) resting tremor (vs. nontremor-dominant); (b) MCI; (c) dementia; (d) impulse control disorders (ICD); (e) depression; and/or (f) hallucinations. We end by discussing the relationship among subtypes of PD subgroups, and the relationship among motor, cognitive, psychiatric factors in PD.

Building a new life: a chaplain's theory based case study of chronic illness

This article presents the case study of spiritual care for a patient suffering from Parkinson's disease who was referred to the chaplain in an out-patient depression research program. The chaplain's interventions were informed by an application of narrative theory, and the article demonstrates how this theory enabled the chaplain to help a patient develop new coping strategies for dealing with chronic disease. Using narrative theory, the chaplain assisted the patient to develop a new sense of identity as a spiritual, contingent self as the disease eroded his physical self and former life. The article includes a description of a patient's spiritual needs, chaplain interventions, and an outcomes measure of those interventions. The author argues that narrative theory provides chaplains with a language to identify and craft the unique intervention that spiritual care has in the life trajectory of this Parkinson's patient and other patients dealing with chronic illnesses.

Age-related differences in working memory: ERPs reveal age-related delays in selection- and inhibition-related processes

Faulty inhibition is implicated in age-related working memory decline. ERP signs of selection and inhibition of items in working memory (WM) are, respectively, a cue-locked parietal positivity (∼ 350 ms) and a probe-locked frontal negativity (∼ 520 ms). To determine when in the older age range differences in selective and inhibitory processes might occur, ERPs were recorded in a WM task from 20 young (20-28), 20 young-old (60-70), and 20 old-old (71-82) adults. A 4-digit display was followed by a cue indicating which 2 of 4 digits were relevant. Proactive interference (PI), the reaction time difference between a matching and non-matching to-be-ignored digit was larger, relative to the young, in both older groups. Compared to the young, both the cue- and probe-locked activities were prolonged in the older groups. Although there were no topographic differences among the age groups, the prolonged PI and associated ERPs suggest a relative age-related deficit in inhibition.

Temporally specific divided attention tasks in young adults reveal the temporal dynamics of episodic encoding failures in elderly adults

Nessler, Johnson, Bersick, and Friedman (D. Nessler, R. Johnson, Jr., M. Bersick, & D. Friedman, 2006, On why the elderly have normal semantic retrieval but deficient episodic encoding: A study of left inferior frontal ERP activity, NeuroImage, Vol. 30, pp. 299-312) found that, compared with young adults, older adults show decreased event-related brain potential (ERP) activity over posterior left inferior prefrontal cortex (pLIPFC) in a 400- to 1,400-ms interval during episodic encoding. This altered brain activity was associated with significantly decreased recognition performance and reduced recollection-related brain activity at retrieval (D. Nessler, D. Friedman, R. Johnson, Jr., & M. Bersick, 2007, Does repetition engender the same retrieval processes in young and older adults? NeuroReport, Vol. 18, pp. 1837-1840). To test the hypothesis that older adults' well-documented episodic retrieval deficit is related to reduced pLIPFC activity at encoding, we used a novel divided attention task in healthy young adults that was specifically timed to disrupt encoding in either the 1st or 2nd half of a 300- to 1,400-ms interval. The results showed that diverting resources for 550 ms during either half of this interval reproduced the 4 characteristic aspects of the older participants' retrieval performance: normal semantic retrieval during encoding, reduced subsequent episodic recognition and recall, reduced recollection-related ERP activity, and the presence of "compensatory" brain activity. We conclude that part of older adults' episodic memory deficit is attributable to altered pLIPFC activity during encoding due to reduced levels of available processing resources. Moreover, the findings also provide insights into the nature and timing of the putative "compensatory" processes posited to be used by older adults in an attempt to compensate for age-related decline in cognitive function. These results support the scaffolding account of compensation, in which the recruitment of additional cognitive processes is an adaptive response across the life span.

Cognitive impairment in Parkinson's disease: the dual syndrome hypothesis

Research into the heterogeneous nature of cognitive impairment documented in patients with Parkinson's disease (PD) has focused on disentangling deficits that vary between individuals, evolve and respond differentially to pharmacological treatments, and relate differentially to PD dementia (PDD). We summarise studies conducted in our laboratory over the last 2 decades, outlining the incremental development of our hypotheses, the starting point for which is our early work on executive deficits mirroring fronto-striatal dysfunction. We present subsequent findings linking these deficits to a model of dopaminergic function that conforms to an inverted curvilinear function. We review studies that investigated the range of dopamine-independent attentional and visuospatial memory deficits seen in PD, demonstrating that abnormalities in these domains more accurately predict PDD. We conclude with an exposition of the dual syndrome hypothesis, which distinguishes between dopaminergically mediated fronto-striatal executive impairments and a dementia syndrome with distinctive prodromal visuospatial deficits in which cholinergic treatments offer some clinical benefits.