Link among apolipoprotein E E4, gait, and cognition in neurodegenerative diseases: ONDRI study

INTRODUCTION

Apolipoprotein E E4 allele (APOE E4) and slow gait are independently associated with cognitive impairment and dementia. However, it is unknown whether their coexistence is associated with poorer cognitive performance and its underlying mechanism in neurodegenerative diseases.

METHODS

Gait speed, APOE E4, cognition, and neuroimaging were assessed in 480 older adults with neurodegeneration. Participants were grouped by APOE E4 presence and slow gait. Mediation analyses were conducted to determine if brain structures could explain the link between these factors and cognitive performance.

RESULTS

APOE E4 carriers with slow gait had the lowest global cognitive performance and smaller gray matter volumes compared to non-APOE E4 carriers with normal gait. Coexistence of APOE E4 and slow gait best predicted global and domain-specific poorer cognitive performances, mediated by smaller gray matter volume.

DISCUSSION

Gait slowness in APOE E4 carriers with neurodegenerative diseases may indicate extensive gray matter changes associated with poor cognition.

HIGHLIGHTS

APOE E4 and slow gait are risk factors for cognitive decline in neurodegenerative diseases. Slow gait and smaller gray matter volumes are associated, independently of APOE E4. Worse cognition in APOE E4 carriers with slow gait is explained by smaller GM volume. Gait slowness in APOE E4 carriers indicates poorer cognition-related brain changes.

Enhanced mind-matter interactions following rTMS induced frontal lobe inhibition

A major barrier to acceptance of psi is that effects are small and hard to replicate. To address this issue, we developed a novel neurobiological model to study this controversial phenomenon based upon the concept that the brain may act as a psi-inhibitory filter. Our previous research in individuals with frontal lobe damage suggests that this filter includes the left medial middle frontal region. We report our findings in healthy participants with rTMS induced reversible brain lesions. In support of our a priori hypothesis, we found a significant psi effect following rTMS inhibition of the left medial middle frontal lobe. This significant effect was found using a post hoc weighting procedure aligned with our overarching hypothesis. This suggests that the brain may inhibit psi and that individuals with neurological or reversible rTMS induced frontal lesions may comprise an enriched sample for detection and replication of this controversial phenomenon. Our findings are potentially transformative for the way we view interactions between the brain and seemingly random events.

Association of plasma biomarkers with cognition, cognitive decline, and daily function across and within neurodegenerative diseases: Results from the Ontario Neurodegenerative Disease Research Initiative

INTRODUCTION

We investigated whether novel plasma biomarkers are associated with cognition, cognitive decline, and functional independence in activities of daily living across and within neurodegenerative diseases.

METHODS

Glial fibrillary acidic protein (GFAP), neurofilament light chain (NfL), phosphorylated tau (p-tau)181 and amyloid beta (Aβ)42/40 were measured using ultra-sensitive Simoa immunoassays in 44 healthy controls and 480 participants diagnosed with Alzheimer's disease/mild cognitive impairment (AD/MCI), Parkinson's disease (PD), frontotemporal dementia (FTD) spectrum disorders, or cerebrovascular disease (CVD).

RESULTS

GFAP, NfL, and/or p-tau181 were elevated among all diseases compared to controls, and were broadly associated with worse baseline cognitive performance, greater cognitive decline, and/or lower functional independence. While GFAP, NfL, and p-tau181 were highly predictive across diseases, p-tau181 was more specific to the AD/MCI cohort. Sparse associations were found in the FTD and CVD cohorts and for Aβ42/40 .

DISCUSSION

GFAP, NfL, and p-tau181 are valuable predictors of cognition and function across common neurodegenerative diseases, and may be useful in specialized clinics and clinical trials.

Rare neurovascular genetic and imaging markers across neurodegenerative diseases

INTRODUCTION

Cerebral small vessel disease (SVD) is common in patients with cognitive impairment and neurodegenerative diseases such as Alzheimer's and Parkinson's. This study investigated the burden of magnetic resonance imaging (MRI)-based markers of SVD in patients with neurodegenerative diseases as a function of rare genetic variant carrier status.

METHODS

The Ontario Neurodegenerative Disease Research Initiative study included 520 participants, recruited from 14 tertiary care centers, diagnosed with various neurodegenerative diseases and determined the carrier status of rare non-synonymous variants in five genes (ABCC6, COL4A1/COL4A2, NOTCH3/HTRA1).

RESULTS

NOTCH3/HTRA1 were found to significantly influence SVD neuroimaging outcomes; however, the mechanisms by which these variants contribute to disease progression or worsen clinical correlates are not yet understood.

DISCUSSION

Further studies are needed to develop genetic and imaging neurovascular markers to enhance our understanding of their potential contribution to neurodegenerative diseases.

Cognitive correlates of antisaccade behaviour across multiple neurodegenerative diseases

Oculomotor tasks generate a potential wealth of behavioural biomarkers for neurodegenerative diseases. Overlap between oculomotor and disease-impaired circuitry reveals the location and severity of disease processes via saccade parameters measured from eye movement tasks such as prosaccade and antisaccade. Existing studies typically examine few saccade parameters in single diseases, using multiple separate neuropsychological test scores to relate oculomotor behaviour to cognition; however, this approach produces inconsistent, ungeneralizable results and fails to consider the cognitive heterogeneity of these diseases. Comprehensive cognitive assessment and direct inter-disease comparison are crucial to accurately reveal potential saccade biomarkers.

We remediate these issues by characterizing twelve behavioural parameters, selected to robustly describe saccade behaviour, derived from an interleaved pro- and antisaccade task in a large cross-sectional dataset comprising five disease cohorts (Alzheimer’s disease/mild cognitive impairment, amyotrophic lateral sclerosis, frontotemporal dementia, Parkinson’s disease, cerebrovascular disease; n=391, age 40-87) and healthy controls (n=149, age 42-87). These participants additionally completed an extensive neuropsychological test battery. We further subdivided each cohort by diagnostic subgroup (for Alzheimer’s disease/mild cognitive impairment and frontotemporal dementia) or degree of cognitive impairment based on neuropsychological testing (all other cohorts). We sought to understand links between oculomotor parameters, their relationships to robust cognitive measures, and their alterations in disease. We performed a factor analysis evaluating interrelationships among the twelve oculomotor parameters and examined correlations of the four resultant factors to five neuropsychology-based cognitive domain scores. We then compared behaviour between the abovementioned disease subgroups and controls at the individual parameter level.

We theorized that each underlying factor measured the integrity of a distinct task-relevant brain process. Notably, factor 3 (voluntary saccade generation) and factor 1 (task disengagements) significantly correlated with attention/working memory and executive function scores. Factor 3 also correlated with memory and visuospatial function scores. Factor 2 (preemptive global inhibition) correlated only with attention/working memory scores, and factor 4 (saccade metrics) correlated with no cognitive domain scores. Impairment on several mostly antisaccade-related individual parameters scaled with cognitive impairment across disease cohorts, while few subgroups differed from controls on prosaccade parameters.

The interleaved pro- and antisaccade task detects cognitive impairment, and subsets of parameters likely index disparate underlying processes related to different cognitive domains. This suggests that the task represents a sensitive paradigm that can simultaneously evaluate a variety of clinically relevant cognitive constructs in neurodegenerative and cerebrovascular diseases and could be developed into a screening tool applicable to multiple diagnoses.

Neuropsychiatric Symptom Burden across Neurodegenerative Disorders and its Association with Function

OBJECTIVE

Neuropsychiatric symptoms (NPS) are prevalent in neurodegenerative disorders, however, their frequency and impact on function across different disorders is not well understood. We compared the frequency and severity of NPS across Alzheimer's disease (AD) (either with mild cognitive impairment or dementia), Cerebrovascular disease (CVD), Parkinson's disease (PD), frontotemporal dementia (FTD), and amyotrophic lateral sclerosis (ALS), and explored the association between NPS burden and function.

METHODS

We obtained data from Ontario Neurodegenerative Disease Research Initiative (ONDRI) that included following cohorts: AD (N = 111), CVD (N = 148), PD (N = 136), FTD (N = 50) and ALS (N = 36). We compared the frequency and severity of individual NPS (assessed by the neuropsychiatric inventory questionnaire) across cohorts using generalized estimating equations and analysis of variance. Second, we assessed the relationship of NPS burden with instrumental (iADLs) and basic (ADLs) activities of living across cohorts using multivariate linear regression while adjusting for relevant demographic and clinical covariates.

RESULTS

Frequency of NPS varied across cohorts (χ²₍₄₎ = 34.4, p < .001), with post-hoc tests showing that FTD had the greatest frequency as compared to all other cohorts. The FTD cohort also had the greatest severity of NPS (H₍₄₎ = 34.5, p < .001). Further, there were differences among cohorts in terms of the association between NPS burden and ADLs (F_(4,461) = 3.1, p = 0.02). Post-hoc comparisons suggested that this finding was driven by the FTD group, however, the differences did not remain significant following Bonferroni correction. There were no differences among cohorts in terms of the association between NPS burden and IADLs.

CONCLUSIONS

NPS frequency and severity are markedly greater in FTD as compared to other neurodegenerative diseases. Further, NPS burden appears to be associated differently with function across neurodegenerative disorders, highlighting the need for individualized clinical interventions.

Characteristics of the Ontario Neurodegenerative Disease Research Initiative cohort

INTRODUCTION

Understanding synergies between neurodegenerative and cerebrovascular pathologies that modify dementia presentation represents an important knowledge gap.

METHODS

This multi-site, longitudinal, observational cohort study recruited participants across prevalent neurodegenerative diseases and cerebrovascular disease and assessed participants comprehensively across modalities. We describe univariate and multivariate baseline features of the cohort and summarize recruitment, data collection, and curation processes.

RESULTS

We enrolled 520 participants across five neurodegenerative and cerebrovascular diseases. Median age was 69 years, median Montreal Cognitive Assessment score was 25, median independence in activities of daily living was 100% for basic and 93% for instrumental activities. Spousal study partners predominated; participants were often male, White, and more educated. Milder disease stages predominated, yet cohorts reflect clinical presentation.

DISCUSSION

Data will be shared with the global scientific community. Within-disease and disease-agnostic approaches are expected to identify markers of severity, progression, and therapy targets. Sampling characteristics also provide guidance for future study design.

Soluble Epoxide Hydrolase Derived Linoleic Acid Oxylipins, Small Vessel Disease Markers, and Neurodegeneration in Stroke

Background Cerebral small vessel disease is associated with higher ratios of soluble-epoxide hydrolase derived linoleic acid diols (12,13-dihydroxyoctadecenoic acid [DiHOME] and 9,10-DiHOME) to their parent epoxides (12(13)-epoxyoctadecenoic acid [EpOME] and 9(10)-EpOME); however, the relationship has not yet been examined in stroke. Methods and Results Participants with mild to moderate small vessel stroke or large vessel stroke were selected based on clinical and imaging criteria. Metabolites were quantified by ultra-high-performance liquid chromatography-mass spectrometry. Volumes of stroke, lacunes, white matter hyperintensities, magnetic resonance imaging visible perivascular spaces, and free water diffusion were quantified from structural and diffusion magnetic resonance imaging (3 Tesla). Adjusted linear regression models were used for analysis. Compared with participants with large vessel stroke (n=30), participants with small vessel stroke (n=50) had a higher 12,13-DiHOME/12(13)-EpOME ratio (β=0.251, P=0.023). The 12,13-DiHOME/12(13)-EpOME ratio was associated with more lacunes (β=0.266, P=0.028) but not with large vessel stroke volumes. Ratios of 12,13-DiHOME/12(13)-EpOME and 9,10-DiHOME/9(10)-EpOME were associated with greater volumes of white matter hyperintensities (β=0.364, P<0.001; β=0.362, P<0.001) and white matter MRI-visible perivascular spaces (β=0.302, P=0.011; β=0.314, P=0.006). In small vessel stroke, the 12,13-DiHOME/12(13)-EpOME ratio was associated with higher white matter free water diffusion (β=0.439, P=0.016), which was specific to the temporal lobe in exploratory regional analyses. The 9,10-DiHOME/9(10)-EpOME ratio was associated with temporal lobe atrophy (β=-0.277, P=0.031). Conclusions Linoleic acid markers of cytochrome P450/soluble-epoxide hydrolase activity were associated with small versus large vessel stroke, with small vessel disease markers consistent with blood brain barrier and neurovascular-glial disruption, and temporal lobe atrophy. The findings may indicate a novel modifiable risk factor for small vessel disease and related neurodegeneration.

Retinal nerve fiber layer in frontotemporal lobar degeneration and amyotrophic lateral sclerosis

Purpose

Tauopathy and transactive response DNA binding protein 43 (TDP-43) proteinopathy are associated with neurodegenerative diseases. These proteinopathies are difficult to detect in vivo. This study examined if spectral-domain optical coherence tomography (SD-OCT) can differentiate in vivo the difference in peripapillary retinal nerve fibre layer (pRNFL) thickness and macular retinal thickness between participants with presumed tauopathy (progressive supranuclear palsy) and those with presumed TDP-43 proteinopathy (amyotrophic lateral sclerosis and semantic variant primary progressive aphasia).

Study design

Prospective, multi-centre, observational study.

Materials and methods

pRNFL and macular SD-OCT images were acquired in both eyes of each participant using Heidelberg Spectralis SD-OCT. Global and pRNFL thickness in 6 sectors were analyzed, as well as macular thickness in a central 1 mm diameter zone and 4 surrounding sectors. Linear mixed model methods adjusting for baseline differences between groups were used to compare the two groups with respect to pRNFL and macular thickness.

Results

A significant difference was found in mean pRNFL thickness between groups, with the TDP-43 group (n = 28 eyes) having a significantly thinner pRNFL in the temporal sector than the tauopathy group (n = 9 eyes; mean difference = 15.46 μm, SE = 6.98, p = 0.046), which was not significant after adjusting for multiple comparisons. No other significant differences were found between groups for pRNFL or macular thickness.

Conclusion

The finding that the temporal pRNFL in the TDP-43 group was on average 15.46 μm thinner could potentially have clinical significance. Future work with larger sample sizes, longitudinal studies, and at the level of retinal sublayers will help to determine the utility of SD-OCT to differentiate between these two proteinopathies.

Targeted copy number variant identification across the neurodegenerative disease spectrum

Background

Although genetic factors are known to contribute to neurodegenerative disease susceptibility, there remains a large amount of heritability unaccounted for across the diagnoses. Copy number variants (CNVs) contribute to these phenotypes, but their presence and influence on disease state remains relatively understudied.

Methods

Here, we applied a depth of coverage approach to detect CNVs in 80 genes previously associated with neurodegenerative disease within participants of the Ontario Neurodegenerative Disease Research Initiative (n = 519).

Results

In total, we identified and validated four CNVs in the cohort, including: (1) a heterozygous deletion of exon 5 in OPTN in an Alzheimer's disease participant; (2) a duplication of exons 1–5 in PARK7 in an amyotrophic lateral sclerosis participant; (3) a duplication of >3 Mb, which encompassed ABCC6, in a cerebrovascular disease (CVD) participant; and (4) a duplication of exons 7–11 in SAMHD1 in a mild cognitive impairment participant. We also identified 43 additional CNVs that may be candidates for future replication studies.

Conclusion

The identification of the CNVs suggests a portion of the apparent missing heritability of the phenotypes may be due to these structural variants, and their assessment is imperative for a thorough understanding of the genetic spectrum of neurodegeneration.

Caregiving concerns and clinical characteristics across neurodegenerative and cerebrovascular disorders in the Ontario neurodegenerative disease research initiative

OBJECTIVES

Caregiving burdens are a substantial concern in the clinical care of persons with neurodegenerative disorders. In the Ontario Neurodegenerative Disease Research Initiative, we used the Zarit's Burden Interview (ZBI) to examine: (1) the types of burdens captured by the ZBI in a cross-disorder sample of neurodegenerative conditions (2) whether there are categorical or disorder-specific effects on caregiving burdens, and (3) which demographic, clinical, and cognitive measures are related to burden(s) in neurodegenerative disorders?

METHODS/DESIGN

N = 504 participants and their study partners (e.g., family, friends) across: Alzheimer's disease/mild cognitive impairment (AD/MCI; n = 120), Parkinson's disease (PD; n = 136), amyotrophic lateral sclerosis (ALS; n = 38), frontotemporal dementia (FTD; n = 53), and cerebrovascular disease (CVD; n = 157). Study partners provided information about themselves, and information about the clinical participants (e.g., activities of daily living (ADL)). We used Correspondence Analysis to identify types of caregiving concerns in the ZBI. We then identified relationships between those concerns and demographic and clinical measures, and a cognitive battery.

RESULTS

We found three components in the ZBI. The first was "overall burden" and was (1) strongly related to increased neuropsychiatric symptoms (NPI severity r = 0.586, NPI distress r = 0.587) and decreased independence in ADL (instrumental ADLs r = -0.566, basic ADLs r = -0.43), (2) moderately related to cognition (MoCA r = -0.268), and (3) showed little-to-no differences between disorders. The second and third components together showed four types of caregiving concerns: current care of the person with the neurodegenerative disease, future care of the person with the neurodegenerative disease, personal concerns of study partners, and social concerns of study partners.

CONCLUSIONS

Our results suggest that the experience of caregiving in neurodegenerative and cerebrovascular diseases is individualized and is not defined by diagnostic categories. Our findings highlight the importance of targeting ADL and neuropsychiatric symptoms with caregiver-personalized solutions.

Virtual Behavioral Medicine Program: A Novel Model of Care for Neuropsychiatric Symptoms in Dementia

BACKGROUND

Patients with severe neuropsychiatric symptoms (NPS) due to dementia are often uprooted from their familiar environments in long-term care or the community and transferred to emergency departments, acute care hospitals, or specialized behavioral units which can exacerbate NPS. To address this issue, we developed the Virtual Behavioral Medicine Program (VBM), an innovative model of virtual care designed to support management of patients with NPS in their own environment.

OBJECTIVE

To determine efficacy of VBM in reducing admission to a specialized inpatient neurobehavioral unit for management of NPS.

METHODS

We reviewed outcomes in the first consecutive 95 patients referred to VBM. Referrals were classified into two groups. In one group, patients were referred to VBM with a simultaneous application to an inpatient Behavioral Neurology Unit (BNU). The other group was referred only to VBM. The primary outcome was reduction in proportion of patients requiring admission to the BNU regardless of whether they were referred to the BNU or to VBM alone.

RESULTS

For patients referred to VBM plus the BNU, the proportion needing admission to the BNU was reduced by 60.42%. For patients referred to VBM alone, it was 68.75%.

CONCLUSION

VBM is a novel virtual neurobehavioral unit for treatment of NPS. Although the sample size was relatively small, especially for the VBM group, the data suggest that this program is a game changer that can reduce preventable emergency department visits and acute care hospital admissions. VBM is a scalable model of virtual care that can be adopted worldwide.

Feasibility of a continuous, multi-sensor remote health monitoring approach in persons living with neurodegenerative disease

BACKGROUND

Remote health monitoring with wearable sensor technology may positively impact patient self-management and clinical care. In individuals with complex health conditions, multi-sensor wear may yield meaningful information about health-related behaviors. Despite available technology, feasibility of device-wearing in daily life has received little attention in persons with physical or cognitive limitations. This mixed methods study assessed the feasibility of continuous, multi-sensor wear in persons with cerebrovascular (CVD) or neurodegenerative disease (NDD).

METHODS

Thirty-nine participants with CVD, Alzheimer's disease/amnestic mild cognitive impairment, frontotemporal dementia, Parkinson's disease, or amyotrophic lateral sclerosis (median age 68 (45-83) years, 36% female) wore five devices (bilateral ankles and wrists, chest) continuously for a 7-day period. Adherence to device wearing was quantified by examining volume and pattern of device removal (non-wear). A thematic analysis of semi-structured de-brief interviews with participants and study partners was used to examine user acceptance.

RESULTS

Adherence to multi-sensor wear, defined as a minimum of three devices worn concurrently, was high (median 98.2% of the study period). Non-wear rates were low across all sensor locations (median 17-22 min/day), with significant differences between some locations (p = 0.006). Multi-sensor non-wear was higher for daytime versus nighttime wear (p < 0.001) and there was a small but significant increase in non-wear over the collection period (p = 0.04). Feedback from de-brief interviews suggested that multi-sensor wear was generally well accepted by both participants and study partners.

CONCLUSION

A continuous, multi-sensor remote health monitoring approach is feasible in a cohort of persons with CVD or NDD.

Contribution of rare variant associations to neurodegenerative disease presentation

Genetic factors contribute to neurodegenerative diseases, with high heritability estimates across diagnoses; however, a large portion of the genetic influence remains poorly understood. Many previous studies have attempted to fill the gaps by performing linkage analyses and association studies in individual disease cohorts, but have failed to consider the clinical and pathological overlap observed across neurodegenerative diseases and the potential for genetic overlap between the phenotypes. Here, we leveraged rare variant association analyses (RVAAs) to elucidate the genetic overlap among multiple neurodegenerative diagnoses, including Alzheimer's disease, amyotrophic lateral sclerosis, frontotemporal dementia (FTD), mild cognitive impairment, and Parkinson's disease (PD), as well as cerebrovascular disease, using the data generated with a custom-designed neurodegenerative disease gene panel in the Ontario Neurodegenerative Disease Research Initiative (ONDRI). As expected, only ~3% of ONDRI participants harboured a monogenic variant likely driving their disease presentation. Yet, when genes were binned based on previous disease associations, we observed an enrichment of putative loss of function variants in PD genes across all ONDRI cohorts. Further, individual gene-based RVAA identified significant enrichment of rare, nonsynonymous variants in PARK2 in the FTD cohort, and in NOTCH3 in the PD cohort. The results indicate that there may be greater heterogeneity in the genetic factors contributing to neurodegeneration than previously appreciated. Although the mechanisms by which these genes contribute to disease presentation must be further explored, we hypothesize they may be a result of rare variants of moderate phenotypic effect contributing to overlapping pathology and clinical features observed across neurodegenerative diagnoses.

Accuracy of a Self-Administered Online Cognitive Assessment in Detecting Amnestic Mild Cognitive Impairment

Objectives

Our aim was to validate the online Brain Health Assessment (BHA) for detection of amnestic mild cognitive impairment (aMCI) compared to gold-standard neuropsychological assessment. We compared the diagnostic accuracy of the BHA to the Montreal Cognitive Assessment (MoCA).

Methods

Using a cross-sectional design, community-dwelling older adults completed a neuropsychological assessment, were diagnosed as normal cognition (NC) or aMCI, and completed the BHA and MoCA. Both logistic regression (LR) and penalized logistic regression (PLR) analyses determined BHA and demographic variables predicting aMCI; MoCA variables were similarly modeled. Diagnostic accuracy was compared using area under the receiver operating characteristic curve (ROC AUC) analyses.

Results

Ninety-one participants met inclusion criteria (51 aMCI, 40 NC). PLR modeling for the BHA indicated Face–Name Association, Spatial Working Memory, and age-predicted aMCI (ROC AUC = 0.76; 95% confidence interval [CI]: 0.66–0.86). Optimal cut-points resulted in 21% classified as aMCI (positive), 23% negative, and 56% inconclusive. For the MoCA, digits, abstraction, delayed recall, orientation, and age predicted aMCI (ROC AUC = 0.71; 95% CI: 0.61–0.82). Optimal cut-points resulted in 22% classified positive, 8% negative, and 70% inconclusive (LR results presented within). The BHA model classified fewer participants into the inconclusive category and more as negative for aMCI, compared to the MoCA model (Stuart–Maxwell p = .004).

Discussion

The self-administered BHA provides similar detection of aMCI as a clinician-administered screener (MoCA), with fewer participants classified inconclusively. The BHA has the potential to save practitioners time and decrease unnecessary referrals for a comprehensive assessment to determine the presence of aMCI.

Bilingualism in Parkinson's disease: Relationship to cognition and quality of life

Some studies have found that bilingualism promotes cognitive reserve.

OBJECTIVE

We aimed to determine whether bilingualism, defined as regularly (i.e. daily) using at least two languages at least since early adulthood, is associated with cognitive advantages in Parkinson's disease (PD) or whether the possible benefits of bilingualism are lost in the context of PD, possibly affecting quality of life (QoL) and independence.

METHOD

Participants with idiopathic PD (n = 140, mean age = 67.9 [SD = 6.4], 78% men) completed standard neuropsychological tasks evaluating attention/working memory, language, executive function, memory, and visuospatial ability, as well as measures of wellbeing and functional independence.

RESULTS

Bilinguals with PD (n = 21) performed worse than monolinguals with PD (n = 92) on attention/working memory and language measures. The between-group differences in attention/working memory were restricted to verbally-based measures. When measured along a continuum, a higher degree of bilingualism was correlated with lower scores on measures of attention/working memory and language. There were no group differences in self- or informant-reported cognitive decline, PD health-related QoL, or functional independence.

CONCLUSIONS

Bilingualism in PD was not associated with better cognitive performance. Lower scores on language-based measures may reflect a distributed fund of linguistic information across more than one language, lower language proficiency in English, and/or other cultural artifacts. Furthermore, using normative data specific to the dominant language spoken or conducting neuropsychological testing in participants' self-reported most proficient language may enhance additional studies addressing this topic. Future research may also examine the roles of bilingualism over time and across other neurodegenerative diseases with and without EF impairment to illuminate further the impact of bilingualism on cognition and QoL, and shape culturally and linguistically diverse research and clinical care.

Parkinson's Disease, NOTCH3 Genetic Variants, and White Matter Hyperintensities

BACKGROUND

White matter hyperintensities (WMH) on magnetic resonance imaging may influence clinical presentation in patients with Parkinson's disease (PD), although their significance and pathophysiological origins remain unresolved. Studies examining WMH have identified pathogenic variants in NOTCH3 as an underlying cause of inherited forms of cerebral small vessel disease.

METHODS

We examined NOTCH3 variants, WMH volumes, and clinical correlates in 139 PD patients in the Ontario Neurodegenerative Disease Research Initiative cohort.

RESULTS

We identified 13 PD patients (~9%) with rare (<1% of general population), nonsynonymous NOTCH3 variants. Bayesian linear modeling demonstrated a doubling of WMH between variant negative and positive patients (3.1 vs. 6.9 mL), with large effect sizes for periventricular WMH (d = 0.8) and lacunes (d = 1.2). Negative correlations were observed between WMH and global cognition (r = -0.2).

CONCLUSION

The NOTCH3 rare variants in PD may significantly contribute to increased WMH burden, which in turn may negatively influence cognition. © 2020 International Parkinson and Movement Disorder Society.

The Quality Assurance and Quality Control Protocol for Neuropsychological Data Collection and Curation in the Ontario Neurodegenerative Disease Research Initiative (ONDRI) Study

As large research initiatives designed to generate big data on clinical cohorts become more common, there is an increasing need to establish standard quality assurance (QA; preventing errors) and quality control (QC; identifying and correcting errors) procedures for critical outcome measures. The present article describes the QA and QC approach developed and implemented for the neuropsychology data collected as part of the Ontario Neurodegenerative Disease Research Initiative study. We report on the efficacy of our approach and provide data quality metrics. Our findings demonstrate that even with a comprehensive QA protocol, the proportion of data errors still can be high. Additionally, we show that several widely used neuropsychological measures are particularly susceptible to error. These findings highlight the need for large research programs to put into place active, comprehensive, and separate QA and QC procedures before, during, and after protocol deployment. Detailed recommendations and considerations for future studies are provided.

The utility of multivariate outlier detection techniques for data quality evaluation in large studies: an application within the ONDRI project

BACKGROUND

Large and complex studies are now routine, and quality assurance and quality control (QC) procedures ensure reliable results and conclusions. Standard procedures may comprise manual verification and double entry, but these labour-intensive methods often leave errors undetected. Outlier detection uses a data-driven approach to identify patterns exhibited by the majority of the data and highlights data points that deviate from these patterns. Univariate methods consider each variable independently, so observations that appear odd only when two or more variables are considered simultaneously remain undetected. We propose a data quality evaluation process that emphasizes the use of multivariate outlier detection for identifying errors, and show that univariate approaches alone are insufficient. Further, we establish an iterative process that uses multiple multivariate approaches, communication between teams, and visualization for other large-scale projects to follow.

METHODS

We illustrate this process with preliminary neuropsychology and gait data for the vascular cognitive impairment cohort from the Ontario Neurodegenerative Disease Research Initiative, a multi-cohort observational study that aims to characterize biomarkers within and between five neurodegenerative diseases. Each dataset was evaluated four times: with and without covariate adjustment using two validated multivariate methods - Minimum Covariance Determinant (MCD) and Candès' Robust Principal Component Analysis (RPCA) - and results were assessed in relation to two univariate methods. Outlying participants identified by multiple multivariate analyses were compiled and communicated to the data teams for verification.

RESULTS

Of 161 and 148 participants in the neuropsychology and gait data, 44 and 43 were flagged by one or both multivariate methods and errors were identified for 8 and 5 participants, respectively. MCD identified all participants with errors, while RPCA identified 6/8 and 3/5 for the neuropsychology and gait data, respectively. Both outperformed univariate approaches. Adjusting for covariates had a minor effect on the participants identified as outliers, though did affect error detection.

CONCLUSIONS

Manual QC procedures are insufficient for large studies as many errors remain undetected. In these data, the MCD outperforms the RPCA for identifying errors, and both are more successful than univariate approaches. Therefore, data-driven multivariate outlier techniques are essential tools for QC as data become more complex.

Cognitive Contributors to Multiple Errands Test (MET) Performance

OBJECTIVE

The Multiple Errands Test (MET) was designed to measure the effect of executive dysfunction on everyday life activities, but little is known about the cognitive requirements for successful performance. This study's objective was to investigate cognitive functions associated with successful MET performance, specifically, the Baycrest-MET.

METHOD

Correlation analysis examined relationships between Baycrest-MET performance and neuropsychological functioning in participants with acquired brain injury (ABI; N = 27).

RESULTS

The association of tasks omitted with executive function (EF) accounted for 15.2%-42.3% of the variance; the association of tasks omitted with attention and processing speed, for 16.8%-24.0%; and the association of tasks omitted and total rule breaks with visuospatial memory, for 18.5%-31.4%.

CONCLUSION

Poor performance on the Baycrest-MET in people with ABI is associated with impairments of EF, attention, memory, and processing speed. Different patterns of performance may arise from different constellations of impairments.

Fit for Dialysis: a qualitative exploration of the impact of a research-based film for the promotion of exercise in hemodialysis

BACKGROUND

Exercise improves functional outcomes and quality of life of older patients with end-stage renal disease undergoing hemodialysis. Yet exercise is not promoted as part of routine care. Health care providers and family carers rarely provide encouragement for patients to exercise, and the majority of older patients remain largely inactive. There is thus the need for a shift in the culture of hemodialysis care towards the promotion of exercise for wellness, including expectations of exercise participation by older patients, and encouragement by health care providers and family carers. Film-based educational initiatives hold promise to effect cultures of best practice, but have yet to be utilized in this population.

METHODS

We developed a research-based film, Fit for Dialysis, to promote exercise for wellness in hemodialysis care. Using a qualitative approach, we evaluated the effects that resulted from engagement with this film (e.g. knowledge/attitudes regarding the importance of exercise-based principles of wellness) as well as the generative mechanisms of these effects (e.g. realism, aesthetics). We also explored the factors related to patients, family carers, and health care providers that influenced engagement with the film, and the successful uptake of the key messages of Fit for Dialysis. We conducted qualitative interviews with 10 patients, 10 health care providers, and 10 family carers. Data were analyzed using thematic analysis.

RESULTS

The film was perceived to be effective in increasing patients', family carers' and health care providers' understanding of the importance of exercise and its benefits, motivating patients to exercise, and in increasing encouragement by family carers and health care providers of patient exercise. Realism (e.g. character identification) and aesthetic qualities of the film (e.g. dialogue) were identified as central generative mechanisms.

CONCLUSIONS

Fit for Dialysis is well-positioned to optimize the health and wellbeing of older adults undergoing hemodialysis.

TRIAL REGISTRATION

NCT02754271 ( ClinicalTrials.gov ), retroactively registered on April 21, 2016.

Neural coupling between contralesional motor and frontoparietal networks correlates with motor ability in individuals with chronic stroke

Movement is traditionally viewed as a process that involves motor brain regions. However, movement also implicates non-motor regions such as prefrontal and parietal cortex, regions whose integrity may thus be important for motor recovery after stroke. Importantly, focal brain damage can affect neural functioning within and between distinct brain networks implicated in the damage. The aim of this study is to investigate how resting state connectivity (rs-connectivity) within and between motor and frontoparietal networks are affected post-stroke in correlation with motor outcome. Twenty-seven participants with chronic stroke with unilateral upper limb deficits underwent motor assessments and magnetic resonance imaging. Participants completed the Chedoke-McMaster Stroke Assessment as a measure of arm (CMSA-Arm) and hand (CMSA-Hand) impairment and the Action Research Arm Test (ARAT) as a measure of motor function. We used a seed-based rs-connectivity approach defining the motor (seed=contralesional primary motor cortex (M1)) and frontoparietal (seed=contralesional dorsolateral prefrontal cortex (DLPFC)) networks. We analyzed the rs-connectivity within each network (intra-network connectivity) and between both networks (inter-network connectivity), and performed correlations between: a) intra-network connectivity and motor assessment scores; b) inter-network connectivity and motor assessment scores. We found: a) Participants with high rs-connectivity within the motor network (between M1 and supplementary motor area) have higher CMSA-Hand stage (z=3.62, p=0.003) and higher ARAT score (z=3.41, p=0.02). Rs-connectivity within the motor network was not significantly correlated with CMSA-Arm stage (z=1.83, p>0.05); b) Participants with high rs-connectivity within the frontoparietal network (between DLPFC and mid-ventrolateral prefrontal cortex) have higher CMSA-Hand stage (z=3.64, p=0.01). Rs-connectivity within the frontoparietal network was not significantly correlated with CMSA-Arm stage (z=0.93, p=0.03) or ARAT score (z=2.53, p=0.05); and c) Participants with high rs-connectivity between motor and frontoparietal networks have higher CMSA-Hand stage (r_s=0.54, p=0.01) and higher ARAT score (r_s=0.54, p=0.009). Rs-connectivity between the motor and frontoparietal networks was not significantly correlated with CMSA-Arm stage (r_s=0.34, p=0.13). Taken together, the connectivity within and between the motor and frontoparietal networks correlate with motor outcome post-stroke. The integrity of these regions may be important for an individual's motor outcome. Motor-frontoparietal connectivity may be a potential biomarker of motor recovery post-stroke.

Cognitive and psychosocial function in retired professional hockey players

BACKGROUND AND OBJECTIVE

The relationship between repeated concussions and neurodegenerative disease has received significant attention, particularly research in postmortem samples. Our objective was to characterise retired professional ice hockey players' cognitive and psychosocial functioning in relation to concussion exposure and apolipoprotein ε4 status.

METHODS

Alumni athletes (N=33, aged 34-71 years) and an age-matched sample of comparison participants (N=18) were administered measures of cognitive function and questionnaires concerning psychosocial and psychiatric functioning.

RESULTS

No significant group differences were found on neuropsychological measures of speeded attention, verbal memory or visuospatial functions, nor were significant differences observed on computerised measures of response speed, inhibitory control and visuospatial problem solving. Reliable group differences in cognitive performance were observed on tests of executive and intellectual function; performance on these measures was associated with concussion exposure. Group differences were observed for cognitive, affective and behavioural impairment on psychosocial questionnaires and psychiatric diagnoses. There was no evidence of differential effects associated with age in the alumni athletes. Possession of an apolipoprotein ε4 allele was associated with increased endorsement of psychiatric complaints, but not with objective cognitive performance.

CONCLUSIONS

We found only subtle objective cognitive impairment in alumni athletes in the context of high subjective complaints and psychiatric impairment. Apolipoprotein ε4 status related to psychiatric, but not cognitive status. These findings provide benchmarks for the degree of cognitive and behavioural impairment in retired professional athletes and a point of comparison for future neuroimaging and longitudinal studies.

Impact of chlorhexidine bathing on methicillin-resistant Staphylococcus aureus incidence in an endemic chronic care setting: A randomized controlled trial

We postulated that bathing with 2% chlorhexidine-impregnated antiseptic washcloths could reduce methicillin-resistant Staphylococcus aureus (MRSA) incidence among chronic care patients compared with nonantiseptic bathing. A total of 122 patients on 3 hospital units were enrolled in a 12-month, cluster-randomized, open-label, controlled trial, with 8 patients becoming MRSA positive. The 2% chlorhexidine-impregnated antiseptic washcloths reduced incidence by 71% (0.1 vs 0.44 cases per 1,000 patient days) (P = .14; Fisher exact). The detected difference was not statistically significant because of a low number of observed events.

The effectiveness of unitization in mitigating age-related relational learning impairments depends on existing cognitive status

Binding relations among items in the transverse patterning (TP) task is dependent on the integrity of the hippocampus and its extended network. Older adults have impaired TP learning, corresponding to age-related reductions in hippocampal volumes. Unitization is a training strategy that can mitigate TP impairments in amnesia by reducing reliance on hippocampal-dependent relational binding and increasing reliance on fused representations. Here we examined whether healthy older adults and those showing early signs of cognitive decline would also benefit from unitization. Although both groups of older adults had neuropsychological performance within the healthy range, their TP learning differed both under standard and unitized training conditions. Healthy older adults with impaired TP learning under standard training benefited from unitized training. Older adults who failed the Montreal Cognitive Assessment (MoCA) showed greater impairments under standard conditions, and showed no evidence of improvement with unitization. These individuals' failures to benefit from unitization may be a consequence of early deficits not seen in older adults who pass the MoCA.

Altered resting-state functional connectivity in cognitively preserved pediatric-onset MS patients and relationship to structural damage and cognitive performance

OBJECTIVE

To evaluate resting-state functional connectivity (FC) and relationship to brain volumes and cognition in a sample of cognitively preserved pediatric-onset multiple sclerosis (MS) patients.

METHODS

Sixteen cognitively intact pediatric-onset MS patients and 15 healthy age- and sex-matched controls underwent cognitive testing and 3T anatomical and functional MRI. Resting-state FC patterns were examined using region-of-interest-based timeseries correlations.

RESULTS

Compared to controls, pediatric-onset MS patients demonstrated higher FC of the precuneus, particularly with the anterior cingulate cortex (z=4.21, p<.001), frontal medial cortex (z=3.48, p<.001), and cerebellum (z=3.72, p<.001). Greater T2 lesion volume and lower normalized thalamic volume were associated with reduced FC of the thalamus, especially for FC with the right superior occipital region (t=-2.87, p=.0123 and t=2.27, p=.04 respectively). FC of the left frontal medial cortex was negatively correlated with composite cognitive z-score in the pediatric-onset MS group (p<.05).

CONCLUSIONS

Greater resting-state FC between posterior and anterior brain regions is present in pediatric-onset MS. With greater disease-related structural pathology, there is a disruption of thalamo-cortical FC. In the absence of actual cognitive impairment, heightened FC of the frontal medial cortex was associated with lower cognitive performance, suggesting that greater functional resources are recruited during resting-state in patients with reduced cognitive efficiency.

Anxiety symptoms in amnestic mild cognitive impairment are associated with medial temporal atrophy and predict conversion to Alzheimer disease

OBJECTIVE

To test the hypothesis that anxiety in amnestic mild cognitive impairment (aMCI) increases rates of conversion to Alzheimer disease (AD) and to identify potential neural mechanisms underlying such an association.

METHODS

Participants (N = 376) with aMCI from the Alzheimer's Disease Neuroimaging Initiative (ADNI) were studied over a median period of 36 months. A Cox proportional-hazards model was used to assess the association between anxiety severity ratings on the Neuropsychiatric Inventory Questionnaire and AD risk. Other variables were depression, memory loss, and MRI-derived AD-related regions of interest (ROIs), including hippocampal, amygdalar, entorhinal cortical (EC) volumes, and EC thickness, In addition, a linear regression model was used to determine the effect of anxiety in aMCI on rates of atrophy within ROIs.

RESULTS

Anxiety severity increased rate of aMCI conversion to AD, after controlling for depression and cognitive decline. The association between anxiety and AD remained significant even with inclusion of ROI baseline values or atrophy rates as explanatory variables. Further, anxiety status predicted greater rates of decrease in EC volume. An association between anxiety and EC thickness missed significance.

CONCLUSION

Anxiety symptoms in aMCI predict conversion to AD, over and beyond the effects of depression, memory loss, or atrophy within AD neuroimaging biomarkers. These findings, together with the greater EC atrophy rate predicted by anxiety, are compatible with the hypothesis that anxiety is not a prodromal noncognitive feature of AD but may accelerate decline toward AD through direct or indirect effects on EC.

The benefits associated with volunteering among seniors: a critical review and recommendations for future research

There is an urgent need to identify lifestyle activities that reduce functional decline and dementia associated with population aging. The goals of this article are to review critically the evidence on the benefits associated with formal volunteering among older adults, propose a theoretical model of how volunteering may reduce functional limitations and dementia risk, and offer recommendations for future research. Database searches identified 113 papers on volunteering benefits in older adults, of which 73 were included. Data from descriptive, cross-sectional, and prospective cohort studies, along with 1 randomized controlled trial, most consistently reveal that volunteering is associated with reduced symptoms of depression, better self-reported health, fewer functional limitations, and lower mortality. The extant evidence provides the basis for a model proposing that volunteering increases social, physical, and cognitive activity (to varying degrees depending on characteristics of the volunteer placement) which, through biological and psychological mechanisms, leads to improved functioning; we further propose that these volunteering-related functional improvements should be associated with reduced dementia risk. Recommendations for future research are that studies (a) include more objective measures of psychosocial, physical, and cognitive functioning; (b) integrate qualitative and quantitative methods in prospective study designs; (c) explore further individual differences in the benefits associated with volunteering; (d) include occupational analyses of volunteers' specific jobs in order to identify their social, physical, and cognitive complexity; (e) investigate the independent versus interactive health benefits associated with volunteering relative to engagement in other forms of activity; and (f) examine the relationship between volunteering and dementia risk.

Effects of bilingualism on the age of onset and progression of MCI and AD: evidence from executive function tests

Previous articles have reported that bilingualism is associated with a substantial delay in the onset of both Alzheimer's disease (AD) and Mild Cognitive Impairment (MCI). The present study reports results from 74 MCI patients and 75 AD patients; approximately half of the patients in each group were bilingual. All patients were interviewed to obtain details of their language use, onset of their condition, and lifestyle habits. Patients performed three executive function (EF) tests from the D-KEFS battery (Trails, Color-Word Interference, Verbal Fluency) on 3 occasions over a period of approximately 1 year. Results replicated the finding that bilingual patients are several years older than comparable monolinguals at both age of symptom onset and date of first clinic visit. This result could not be attributed to language group differences in such lifestyle variables as diet, smoking, alcohol consumption, physical activity, or social activity. On the first testing occasion, performance on the EF tasks was generally comparable between the language groups, contesting arguments that bilinguals wait longer before attending the clinic. Finally, EF performance tended to decline over the 3 sessions, but no differences were found between monolinguals and bilinguals in the rate of decline.

Managing executive dysfunction following acquired brain injury and stroke using an ecologically valid rehabilitation approach: a study protocol for a randomized, controlled trial

Background

We have been investigating an ecologically valid strategy-training approach to enable adults with executive dysfunction to attain everyday life goals. Here, we report the protocol of a randomized controlled trial of the effects of this training compared to conventional therapy in a sample of community-dwelling adults with acquired brain injury and/or stroke.

Methods/design

We will recruit 100 community-dwelling survivors at least six months post-acquired brain injury or stroke who report executive dysfunction during a telephone interview, confirmed in pre-training testing. Following pre-training testing, participants will be randomized to the ecologically valid strategy training or conventional therapy and receive two one-hour sessions for eight weeks (maximum of 15 hours of therapy). Post-testing will occur immediately following the training and three months later. The primary outcome is self-reported change in performance on everyday life activities measured using the Canadian Occupational Performance Measure, a standardized, semi-structured interview. Secondary outcomes are objective measurement of performance change from videotapes of treatment session, Performance Quality Rating Scale; executive dysfunction symptoms, Behavioural Rating Inventory of Executive Function – Adult; participation in everyday life, Mayo-Portland Adaptability Inventory Participation Index; and ability to solve novel problems, Instrumental Activities of Daily Living Profile.

Discussion

This study is of a novel approach to promoting improvements in attainment of everyday life goals through managing executive dysfunction using an ecologically valid strategy training approach, the Cognitive Orientation to daily Occupational Performance. This study compares the efficacy of this approach with that of conventional therapy. The approach has the potential to be a valuable treatment for people with chronic acquired brain injury and/or stroke.

Trial registration

clinicaltrials.gov, Trial Identification Number: NCT01414348

Age-related differences in the sequential organization of speech sounds

This study investigated the effects of age on listeners' tendency to group speech tokens into one or two auditory streams. Younger and older adults were presented with sequences of four vowel sounds, which were arranged according to the proximity of first-formant frequencies between adjacent vowels. In Experiment 1, participants were less accurate in identifying the order of the four vowels and more likely to report hearing two streams when the first-formant alternated between low and high frequency and the overall difference between adjacent vowels was large. This effect of first-formant continuity on temporal order judgments and probability of hearing two streams was higher in younger than in older adults. In Experiment 2, participants indicated whether there was rhythm irregularity in an otherwise isochronous sequence of four vowels. Young adults' thresholds were lower when successive first-formants ascended or descended monotonically (condition promoting integration) than when they alternated discontinuously (condition promoting streaming). This effect was not observed in older adults whose thresholds were comparable for both types of vowel sequences. These two experiments provide converging evidence for an age-related deficit in exploiting first-formant information between consecutive vowels, which appear to impede older adults' ability to sequentially group speech sounds over time.

Hippocampal lesions produce both nongraded and temporally graded retrograde amnesia in the same rat

Rats were administered contextual fear conditioning and trained on a water-maze, spatial memory task 28 days or 24 h before undergoing hippocampal lesion or control surgery. When tested postoperatively on both tasks, rats with hippocampal lesions exhibited retrograde amnesia for spatial memory at both delays but temporally graded retrograde amnesia for the contextual fear response. In demonstrating both types of retrograde amnesia in the same animals, the results parallel similar observations in human amnesics with hippocampal damage and provide compelling evidence that the nature of the task and the type of information being accessed are crucial factors in determining the pattern of retrograde memory loss associated with hippocampal damage. The results are interpreted as consistent with our transformation hypothesis (Winocur et al. (2010a) Neuropsychologia 48:2339-2356; Winocur and Moscovitch (2011) J Int Neuropsychol Soc 17:766-780) and at variance with standard consolidation theory and other theoretical models of memory.

Trajectories of behavioral disturbance in dementia

Predicting the progression of dementia is a challenge for clinicians yet this information is highly valued by patients' families. An informally observed 4-stage model of dementia can be helpful in educating caregivers and preparing them for what lies ahead. In the behavioral variant of frontotemporal dementia (bvFTD), this model describes the evolution of behavioral disturbances and is characterized by an inflection point between stage 2 (progressively severe behavioral aberration) and stage 3 (increasing apathy and remission of behavior problems). In this study, we sought evidence for this model using a database of serial Neuropsychiatric Inventory (NPI) scores for 45 patients with FTD and 47 patients with Alzheimer's disease (AD). We transformed the NPI scores into a single variable for each participant that represented the yearly rate of change in total NPI score and used this as the dependent variable in a multivariate linear regression. Age at onset of dementia, NPI score at initial visit, and duration of illness at first NPI all contributed significantly to the regression model in the bvFTD group. Participants with an initial NPI acquired before 6 years of disease duration tended to have a more positive rate of change in NPI total score (representing worsening behavioral disturbances) than those with an initial NPI performed after 6 years. None of the aforementioned variables were significantly associated with yearly change in NPI total score in the AD group. These results support a crescendo-decrescendo trajectory of behavioral symptoms in bvFTD but do not suggest that there is a similar pattern in AD, and further longitudinal data collection is necessary.

Distribution of outbreak reporting in health care institutions by day of the week

BACKGROUND

The notion that outbreaks are more likely to occur on Friday is prevalent among staff in health care institutions. However, there is little evidence to support or discredit this notion. We postulated that outbreaks were no more likely to be reported on any particular day of the week.

METHODS

A total of 901 institutional outbreaks in Toronto health care facilities were tabulated according to type, outbreak setting, and day of the week reported. A χ(2) goodness-of-fit test compared daily values for 7-day per week and 5-day per week periods. Post hoc partitioning was used to pinpoint specific day(s) of the week that differed significantly.

RESULTS

Fewer outbreaks were reported on Saturdays and Sundays. Further analysis examined the distribution of outbreak reporting specifically focusing on the Monday to Friday weekday period. Among the weekdays, higher proportions of outbreaks were reported on Mondays and Fridays.

CONCLUSION

Our null hypothesis was rejected. Overall, Mondays and Fridays had the highest occurrence of outbreak reporting. We suggest that this might be due to "deadline" and "catch-up" reporting related to the "weekend effect," whereby structural differences in weekend staffing affect detection of outbreaks. Such delays warrant reexamination of surveillance processes for timely outbreak detection independent of calendar cycle.

Remote spatial memory in aging: all is not lost

The ability to acquire and retain spatial memories in order to navigate in new environments is known to decline with age, but little is known about the effect of aging on representations of environments learned long ago, in the remote past. To investigate the status of remote spatial memory in old age, we tested healthy young and older adults on a variety of mental navigation tests based on a large-scale city environment that was very familiar to participants but rarely visited by the older adults in recent years. We show that whereas performance on a route learning test of new spatial learning was significantly worse in older than younger adults, performance was comparable or better in the older adults on mental navigation tests based on a well-known environment learned long ago. An exception was in the older adults' ability to vividly re-experience the well-known environment, and recognize and represent the visual details contained within it. The results are seen as analogous to the pattern of better semantic than episodic memory that has been found to accompany healthy aging.

The effects of chemotherapy on cognitive function in a mouse model: a prospective study

PURPOSE

Clinical studies indicate that up to 70% of patients with cancer who receive chemotherapy experience cognitive impairment. The present study used a prospective longitudinal design to assess short- and long-term effects of commonly used anticancer drugs on cognitive performance in a mouse model.

EXPERIMENTAL DESIGN

Normal mice received three weekly injections of a combination of methotrexate + 5-fluorouracil (CHEMO group) or an equal volume of saline (SAL group). Cognitive tests, measuring different aspects of learning and memory, were administered before treatment, immediately after treatment, and three months later. Structural MRI scanning was conducted at each stage of cognitive testing.

RESULTS

The CHEMO group exhibited deficits on cognitive tasks acquired pretreatment [spatial memory, nonmatching-to-sample (NMTS) learning, and delayed NMTS], as well as impaired new learning on two tasks (conditional associative learning, discrimination learning) introduced posttreatment. Consistent with clinical evidence, cognitive deficits were pronounced on tests that are sensitive to hippocampal and frontal lobe dysfunction, but the CHEMO group's poor performance on the discrimination learning problem suggests that impairment is more widespread than previously thought. Cognitive deficits persisted for at least three months after treatment but some recovery was noted, particularly on tests thought to be under frontal lobe control. The MRI tests did not detect brain changes that could be attributed to treatment.

CONCLUSIONS

Chemotherapeutic agents can have adverse effects on information acquired pretreatment as well as new learning and memory and, despite some recovery, impairment is long lasting.

Can changes in eye movement scanning alter the age-related deficit in recognition memory?

Older adults typically exhibit poorer face recognition compared to younger adults. These recognition differences may be due to underlying age-related changes in eye movement scanning. We examined whether older adults' recognition could be improved by yoking their eye movements to those of younger adults. Participants studied younger and older faces, under free viewing conditions (bases), through a gaze-contingent moving window (own), or a moving window which replayed the eye movements of a base participant (yoked). During the recognition test, participants freely viewed the faces with no viewing restrictions. Own-age recognition biases were observed for older adults in all viewing conditions, suggesting that this effect occurs independently of scanning. Participants in the bases condition had the highest recognition accuracy, and participants in the yoked condition were more accurate than participants in the own condition. Among yoked participants, recognition did not depend on age of the base participant. These results suggest that successful encoding for all participants requires the bottom-up contribution of peripheral information, regardless of the locus of control of the viewer. Although altering the pattern of eye movements did not increase recognition, the amount of sampling of the face during encoding predicted subsequent recognition accuracy for all participants. Increased sampling may confer some advantages for subsequent recognition, particularly for people who have declining memory abilities.

Right frontal lobe mediation of recollection- and familiarity-based verbal recognition memory: evidence from patients with tumor resections

Medial-temporal, parietal, and pFC regions have been implicated in recollection and familiarity, but existing evidence from neuroimaging and patient studies is limited and conflicting regarding the role of specific regions within pFC in these memory processes. We report a study of 20 patients who had undergone resection of right frontal lobe tumors and 20 matched healthy control participants. The location and extent of lesions were traced on the patients' scans. A process dissociation procedure was employed to yield estimates of the contributions of recollection and familiarity in verbal recognition performance. Group comparisons revealed deficits in recollection but not familiarity in the patient group relative to their healthy counterparts. We found a positive relationship between estimates of familiarity and lesion sizes in the right inferior pFC (BA 11, 47) which was significant upon bootstrap resampling. These results are discussed in terms of prior work linking this area to an overextended sense of familiarity.

Open-label study of the short-term effects of memantine on FDG-PET in frontotemporal dementia

BACKGROUND

Memantine has shown effects on cortical metabolism in Alzheimer's disease (AD), and the mechanism of action may not be specific to AD alone. We hypothesized that participants with frontotemporal dementia taking memantine would show an increased cortical metabolic activity in frontal regions, temporal regions, or in salience network hubs.

METHODS

Sixteen participants with behavioral or language variant frontotemporal dementia syndromes (FTD) were recruited from tertiary FTD clinics and treated with memantine hydrochloride 10 mg twice daily in this fixed-dose, open-label pilot study. The primary endpoint was enhancement of cortical metabolic activity after 7-8 weeks of treatment. Secondary endpoints were measures of mood and behavior disturbance, frontal executive function, and motor disturbance.

RESULTS

Voxel-wise parametric image analysis of positron emission tomography (PET) data from seven behavioral variant FTD patients, eight semantic dementia patients, and one progressive nonfluent aphasia patient, of mean age 64.3 years, mean duration of illness 4.25 years, and baseline mean sum of boxes Clinical Dementia Rating score 6.59, revealed an increase in [(18)F]-fluorodeoxyglucose (FDG) normalized metabolic activity in bilateral insulae and the left orbitofrontal cortex (P < 0.01). The increase on FDG-PET did not correlate with changes on behavioral inventories. Post hoc analysis indicated that semantic dementia participants drove this finding.

CONCLUSION

This open-label clinical PET study suggests that memantine induces an increase in metabolism in the salience network in FTD. A placebo-controlled follow-up study is warranted.