Cognitive Reserve in Early Manifest Huntington Disease Patients: Leisure Time Is Associated with Lower Cognitive and Functional Impairment

The causal relationship between human brain morphometry and knee osteoarthritis: a two-sample Mendelian randomization study

Background

Knee Osteoarthritis (KOA) is a prevalent and debilitating condition affecting millions worldwide, yet its underlying etiology remains poorly understood. Recent advances in neuroimaging and genetic methodologies offer new avenues to explore the potential neuropsychological contributions to KOA. This study aims to investigate the causal relationships between brain-wide morphometric variations and KOA using a genetic epidemiology approach.

Method

Leveraging data from 36,778 UK Biobank participants for human brain morphometry and 487,411 UK Biobank participants for KOA, this research employed a two-sample Mendelian Randomization (TSMR) approach to explore the causal effects of 83 brain-wide volumes on KOA. The primary method of analysis was the Inverse Variance Weighted (IVW) and Wald Ratio (WR) method, complemented by MR Egger and IVW methods for heterogeneity and pleiotropy assessments. A significance threshold of p < 0.05 was set to determine causality. The analysis results were assessed for heterogeneity using the MR Egger and IVW methods. Brain-wide volumes with Q_pval < 0.05 were considered indicative of heterogeneity. The MR Egger method was employed to evaluate the pleiotropy of the analysis results, with brain-wide volumes having a p-value < 0.05 considered suggestive of pleiotropy.

Results

Our findings revealed significant causal associations between KOA and eight brain-wide volumes: Left parahippocampal volume, Right posterior cingulate volume, Left transverse temporal volume, Left caudal anterior cingulate volume, Right paracentral volume, Left paracentral volume, Right lateral orbitofrontal volume, and Left superior temporal volume. These associations remained robust after tests for heterogeneity and pleiotropy, underscoring their potential role in the pathogenesis of KOA.

Conclusion

This study provides novel evidence of the causal relationships between specific brain morphometries and KOA, suggesting that neuroanatomical variations might contribute to the risk and development of KOA. These findings pave the way for further research into the neurobiological mechanisms underlying KOA and may eventually lead to the development of new intervention strategies targeting these neuropsychological pathways.

Modifiable factors associated with Huntington's disease progression in presymptomatic participants

OBJECTIVE

Huntington's disease (HD) is a neurodegenerative disorder characterized by progressive motor, cognitive, and psychiatric symptoms. Our aim here was to identify factors that can be modified to slow disease progression even before the first symptoms appear.

METHODS

We included 2636 presymptomatic individuals (comparison with family controls) drawn from the prospective observational cohort Enroll-HD, with more than 35 CAG repeats and at least two assessments of disease progression measured with the composite Huntington's disease rating Scale (cUHDRS). The association between sociodemographic factors, health behaviors, health history, and cUHDRS trajectory was assessed with a mixed-effects random forest using partial dependence plots and Shapley additive explanation method.

RESULTS

Participants were followed by an average of 3.4 (SD = 1.97) years. We confirmed the negative impact of age and a high number of CAG repeats. We found that a high level of education, a body mass index (BMI) <23 kg/m2 before the age of 40 and >23 kg/m2 thereafter, alcohol consumption of <15 units per week, current coffee consumption and no smoking were linked to slow disease progression, as did no previous exposure to antidepressants or anxiolytic, no psychiatric history or comorbidities, and being female. Other comorbidities or marital status showed no major association with HD evolution.

INTERPRETATION

Reducing modifiable risk factors for HD is one way to support the presymptomatic population. A high level of education, low-to-moderate alcohol consumption, no smoking, and BMI control are likely to slow disease progression in this population.

Mild cognitive impairment in Huntington's disease: challenges and outlooks

Although Huntington's disease (HD) has classically been viewed as an autosomal-dominant inherited neurodegenerative motor disorder, cognitive and/or behavioral changes are predominant and often an early manifestation of disease. About 40% of individuals in the presymptomatic period of HD meet the criteria for mild cognitive impairment, later progressing to dementia. The heterogenous spectrum of cognitive decline is characterized by deficits across multiple domains, particularly executive dysfunctions, but the underlying pathogenic mechanisms are still poorly understood. Investigating the pathophysiology of cognitive changes may give insight into important and early neurodegenerative events. Multimodal imaging revealed circuit-wide gray and white matter degenerative processes in several key brain regions, affecting prefronto-striatal/cortico-basal ganglia circuits and many other functional brain networks. Studies in transgenic animal models indicated early synaptic dysfunction, deficient neurotrophic transport and other molecular changes contributing to neuronal death. Synaptopathy within the cerebral cortex, striatum and hippocampus may be particularly important in mediating cognitive and neuropsychiatric manifestations of HD, although many other neuronal systems are involved. The interaction of mutant huntingtin protein (mHTT) with tau and its implication for cognitive impairment in HD is a matter of discussion. Further neuroimaging and neuropathological studies are warranted to better elucidate early pathophysiological mechanisms and to develop validated biomarkers to detect patients' cognitive status during the early stages of the condition significantly to implement effective preventing or management strategies.

Prodromal Cognitive Changes as a Prognostic Indicator of Forthcoming Huntington's Disease Severity: A Retrospective Longitudinal Study

BACKGROUND

Cognitive changes in Huntington's disease (HD) precede motor manifestations. ENROLL-HD platform includes four cognitive measures of information processing speed (IPS). Our group is eager to seek clinical markers in the life stage that is as close as possible to the age of onset (ie, the so called prodromal HD phase) because this is the best time for therapeutic interventions.

OBJECTIVES

Our study aimed to test whether cognitive scores in prodromal ENROLL-HD mutation carriers show the potential to predict the severity of motor and behavioral changes once HD became fully manifested.

METHODS

From the global ENROLL-HD cohort of 21,343 participants, we first selected a premanifest Cohort#1 (ie, subjects with Total Motor Score (TMS) <10 and Diagnostic Confidence Level (DCL) <4, N = 1.222). From this cohort, we then focused on a prodromal Cohort#2 of subjects who were ascertained to phenoconvert into manifest HD at follow-up visits (ie, subjects from 6 ≤ TMS≤9 and DCL <4 to TMS≥10 and DCL = 4, n = 206).

RESULTS

The main results of our study showed that low IPS before phenoconversion in Cohort#2 predicted the severity of motor and behavioral manifestations. By combining the four IPS cognitive measures (eg, the Categorical Verbal Fluency Test; Stroop Color Naming Test; Stroop Word Reading; Symbol Digit Modalities Test), we generated a Composite Cognition Score (CCS). The lower the CCS score the higher the TMS and the apathy scores in the same longitudinally followed-up patients after phenoconversion.

CONCLUSIONS

CCS might represent a clinical instrument to predict the prognosis of mutation carriers who are close to manifesting HD.

Validation of the Cognitive Reserve Index Questionnaire (CRIq) in Arabic

Cognitive reserve is the adaptability of cognitive processes in the face of brain aging and pathology. This study aimed to validate the Arabic version of the Cognitive Reserve Index Questionnaire (CRIq) in a healthy Lebanese sample. CRIq assesses cognitive reserve through three domains: education, working activity, and leisure time. Statistical measures, including descriptive and regression analysis along with structural equation modeling, were utilized to investigate the convergent and discriminant validity of the CRIq, incorporating fluid intelligence (Gf) and measures of cognitive function, long-term memory encoding and retrieval (Glr), and processing speed (Gs). Results from 174 participants revealed that the activities assessed by the CRIq-Arabic were comparable to the original CRIq study, with slight cultural differences. The internal consistency of the CRIq-Arabic was good (Cronbach's α = 0.88), indicating reliability. Convergent validity was confirmed, with moderate to high loadings on the cognitive reserve latent construct. Discriminant validity was supported as correlations between cognitive reserve variables and non-target constructs (Gf, Glr, and Gs) were less than 1. The findings provide an initial psychometric validation of the CRIq-Arabic. Further research of clinical samples is needed to enhance its utility in neuropsychological practice.

Effects of Physical Activity on Cognitive Functioning: The Role of Cognitive Reserve and Active Aging

BACKGROUND

The increase in average life expectancy necessitates the identification of possible mechanisms capable of promoting "active aging" to ensure adequate levels of global functioning. Numerous studies show that regular physical activity promotes, even in the elderly, a state of functional psychophysical well-being capable of slowing down age-related cognitive decline. This study aimed to clarify whether, and how, the intensity of physical activity can modulate cognitive and executive skills by influencing specific psychological variables.

METHODS

Our sample consisted of 151 senior subjects divided into hikers (HIK), gentle gymnastics (GYM), and sedentary (SED), who practice intense, moderate, and reduced physical activity, respectively. A battery of psychological questionnaires was administrated to evaluate attentional skills, decision-making, the ability to implement targeted behaviors, perceived self-efficacy, and psychophysical well-being. We included: the Mini-Mental State Examination, Cognitive Reserve Index Questionnaire, General Self-Efficacy Scale, Letter Cancellation Test, Everyday Competence Questionnaire, and Geriatric Depression Scale (GDS).

RESULTS

Comparisons between the scores reported by the three groups showed that the HIK group differs from the others with respect to most of the measurements, presenting better mood and cognitive performance, and a specific psychological profile. On the contrary, the GYM group appeared to have a greater affinity with the SED group than with the HIK group, both cognitively and psychologically.

CONCLUSIONS

Types of physical activity, as well as the intensity and frequency with which they are practiced, are factors that promote an active aging process, protecting the psychophysical well-being and overall cognitive functioning of the elderly.

Distinct reserve capacity impacts on default-mode network in response to left angular gyrus-navigated repetitive transcranial magnetic stimulation in the prodromal Alzheimer disease

Default-mode network (DMN) may be the earliest affected network and is associated with cognitive decline in Alzheimer's disease (AD). Repetitive transcranial magnetic stimulation (rTMS) may help to modulate DMN plasticity. Still, stimulation effects substantially vary across studies and individuals. Global left frontal cortex (gLFC) connectivity, a substitute for reserve capacity, may contribute to the heterogeneous physiological effects of neuro-navigated rTMS. This study investigated the effects of left angular gyrus-navigated rTMS on DMN connectivity in different reserve capacity participants. gLFC connectivity, was computed through resting-state fMRI correlations. Thirty-one prodromal AD patients were divided into low connection group (LCG) and high connection group (HCG) by the median of gLFC connectivity. Distinct reserve capacity impacts on DMN in response to rTMS were identified in these two groups. Then, brain-behavior relationships were examined. gLFC connectivity within a certain range is directly proportional to cognitive reserve ability (i.e., LCG), and the effectiveness of functional connectivity beyond this range decreases (i.e, HCG). Moreover, LCG exhibited increased DMN connectivity and significantly positive memory improvements, while HCG showed a contrary connectivity decline and maintained or slightly improved their cognitive function after neuro-navigated rTMS treatment. The prodromal AD patients with the distinct reserve capacity may benefit differently from left angular gyrus-navigated rTMS, which may lead to increasing attention in defining personalized medicine approach of AD.

Prevalence of motoric cognitive risk syndrome among older adults: a systematic review and meta-analysis

OBJECTIVE

Motoric cognitive risk syndrome (MCR) is a newly proposed pre-dementia syndrome. Several studies on the prevalence of MCR have been published; however, the data vary across studies with different epidemiological characteristics. Thus, this study aimed to quantitatively analyse the overall prevalence and associated epidemiological characteristics of MCR among older adults aged ≥ 60 years.

METHODS

The Cochrane Library, PubMed, Web of Science, CINAHL, Embase, Scopus, PsycInfo, China National Knowledge Infrastructure, Weipu Database, China Biology Medicine disc and Wanfang Database were searched from their inception to January 2022. A modified Newcastle-Ottawa Scale evaluated the risk of bias. Statistical heterogeneity among the included studies was analysed using Cochran's Q and I² tests. A random effect model calculated pooled prevalence owing to study heterogeneity. Begg's and Egger's tests were used to assess the publication bias. Additionally, subgroup analysis and meta-regression were performed based on different epidemiological characteristics to determine heterogeneity sources.

RESULTS

Sixty-two studies comprising 187,558 samples were obtained. The pooled MCR prevalence was 9.0% (95% confidence interval: 8.3-9.8). A higher MCR prevalence was observed in females, older adults with a low educational level, depression and cardiovascular risk factors, South American populations, and studies with small sample sizes and cross-section designs. Furthermore, subjective cognitive complaint using scale score and gait speed using instrument gait showed higher MCR prevalence.

CONCLUSION

MCR is common in older adults, and various epidemiological characteristics influence its prevalence. Thus, preventive measures are required for older adults with higher MCR prevalence.

Beyond the CAG triplet number: exploring potential predictors of delayed age of onset in Huntington's disease

OBJECTIVE

Huntington's disease (HD) is a genetic neurodegenerative disease characterized by cognitive, motor, and psychiatric dysfunction. It is caused by an expansion of the trinucleotide repeat sequence cytosine-adenine-guanine (CAG) in the Huntingtin gene on chromosome 4. Onset typically occurs in the fourth or fifth decade, ranging from childhood to late adulthood. The CAG triplet number is generally inversely proportional to the age of onset (AOO), but the repeat number only accounts for ∼70% of the variability in AOO. Several studies demonstrated the impact of genetic modifiers on age of disease onset. In addition to genetics, we also explored the demographic, anamnestic, and socio-environmental factors that can affect AOO, to help us understand the non-genetic variability of age of onset in HD.

METHODS

We analyzed the retrospective data of the ENROLL-HD global registry study, particularly focusing on the continuum of ages, to include sociodemographic, genetic, and anamnestic psychobehavioral variables in a multivariate regression model aimed at identifying the potential predictors of age of motor onset (n = 5053). We ran the same regression model in the sample of subjects who had the same number of triplets (41 CAG, n = 593) and in the sample whose family history was absent/unknown (n = 630).

RESULTS

Patients with delayed onset more frequently have unknown/missing family history, are married or widowed, live in larger urbanized contexts and have a lower educational level. Individuals with earlier onset more frequently develop psychobehavioral symptoms.

CONCLUSIONS

In the past, the HD gene was considered the epitome of genetic determinism. Our results are consistent with recent evidence that other factors might modulate its impact. These findings allow characterizing the determinants of AOO beyond the CAG expansions and provide valuable information for stratifying patients for future clinical trial designs.