Evolution of Glutamate Metabolism via GLUD2 Enhances Lactate-Dependent Synaptic Plasticity and Complex Cognition

Human evolution is characterized by rapid brain enlargement and the emergence of unique cognitive abilities. Besides its distinctive cytoarchitectural organization and extensive inter-neuronal connectivity, the human brain is also defined by high rates of synaptic, mainly glutamatergic, transmission, and energy utilization. While these adaptations' origins remain elusive, evolutionary changes occurred in synaptic glutamate metabolism in the common ancestor of humans and apes via the emergence of GLUD2, a gene encoding the human glutamate dehydrogenase 2 (hGDH2) isoenzyme. Driven by positive selection, hGDH2 became adapted to function upon intense excitatory firing, a process central to the long-term strengthening of synaptic connections. It also gained expression in brain astrocytes and cortical pyramidal neurons, including the CA1-CA3 hippocampal cells, neurons crucial to cognition. In mice transgenic for GLUD2, theta-burst-evoked long-term potentiation (LTP) is markedly enhanced in hippocampal CA3-CA1 synapses, with patch-clamp recordings from CA1 pyramidal neurons revealing increased sNMDA receptor currents. D-lactate blocked LTP enhancement, implying that glutamate metabolism via hGDH2 potentiates L-lactate-dependent glia-neuron interaction, a process essential to memory consolidation. The transgenic (Tg) mice exhibited increased dendritic spine density/synaptogenesis in the hippocampus and improved complex cognitive functions. Hence, enhancement of neuron-glia communication, via GLUD2 evolution, likely contributed to human cognitive advancement by potentiating synaptic plasticity and inter-neuronal connectivity.

Structural Evolution of Primate Glutamate Dehydrogenase 2 as Revealed by In Silico Predictions and Experimentally Determined Structures

Glutamate dehydrogenase (GDH) interconverts glutamate to a-ketoglutarate and ammonia, interconnecting amino acid and carbohydrate metabolism. In humans, two functional GDH genes, GLUD1 and GLUD2, encode for hGDH1 and hGDH2, respectively. GLUD2 evolved from retrotransposition of the GLUD1 gene in the common ancestor of modern apes. These two isoenzymes are involved in the pathophysiology of human metabolic, neoplastic, and neurodegenerative disorders. The 3D structures of hGDH1 and hGDH2 have been experimentally determined; however, no information is available about the path of GDH2 structure changes during primate evolution. Here, we compare the structures predicted by the AlphaFold Colab method for the GDH2 enzyme of modern apes and their extinct primate ancestors. Also, we analyze the individual effect of amino acid substitutions emerging during primate evolution. Our most important finding is that the predicted structure of GDH2 in the common ancestor of apes was the steppingstone for the structural evolution of primate GDH2s. Two changes with a strong functional impact occurring at the first evolutionary step, Arg443Ser and Gly456Ala, had a destabilizing and stabilizing effect, respectively, making this step the most important one. Subsequently, GDH2 underwent additional modifications that fine-tuned its enzymatic properties to adapt to the functional needs of modern-day primate tissues.

Long-term associations between objective sleep quality and quantity and verbal memory performance in normal cognition and mild cognitive impairment

Introduction

Although the link between sleep and memory function is well established, associations between sleep macrostructure and memory function in normal cognition and Mild Cognitive Impairment remain unclear. We aimed to investigate the longitudinal associations of baseline objectively assessed sleep quality and duration, as well as time in bed, with verbal memory capacity over a 7-9 year period. Participants are a well-characterized subsample of 148 persons (mean age at baseline: 72.8 ± 6.7 years) from the Cretan Aging Cohort. Based on comprehensive neuropsychiatric and neuropsychological evaluation at baseline, participants were diagnosed with Mild Cognitive Impairment (MCI; n = 79) or found to be cognitively unimpaired (CNI; n = 69). Sleep quality/quantity was estimated from a 3-day consecutive actigraphy recording, whereas verbal memory capacity was examined using the Rey Auditory Verbal Learning Test (RAVLT) and the Greek Passage Memory Test at baseline and follow-up. Panel models were applied to the data using AMOS including several sociodemographic and clinical covariates.

Results

Sleep efficiency at baseline directly predicted subsequent memory performance in the total group (immediate passage recall: β = 0.266, p = 0.001; immediate word list recall: β = 0.172, p = 0.01; delayed passage retrieval: β = 0.214, p = 0.002) with the effects in Passage Memory reaching significance in both clinical groups. Wake after sleep onset time directly predicted follow-up immediate passage recall in the total sample (β = -0.211, p = 0.001) and in the MCI group (β = -0.235, p = 0.02). In the total sample, longer 24-h sleep duration was associated with reduced memory performance indirectly through increased sleep duration at follow-up (immediate passage recall: β = -0.045, p = 0.01; passage retention index: β = -0.051, p = 0.01; RAVLT-delayed recall: β = -0.048, p = 0.009; RAVLT-retention index:β = -0.066, p = 0.004). Similar indirect effects were found for baseline 24-h time in bed. Indirect effects of sleep duration/time in bed were found predominantly in the MCI group.

Discussion

Findings corroborate and expand previous work suggesting that poor sleep quality and long sleep duration predict worse memory function in elderly. Timely interventions to improve sleep could help prevent or delay age-related memory decline among non-demented elderly.

SPECT/CT SUV-based metrics: A promising diagnostic tool in classifying patients with suspected transthyretin cardiac amyloidosis among the different Perugini grades?

OBJECTIVE

The purpose of this study was to evaluate the contribution of single photon emission computed tomography/computed tomography (SPECT/CT) standardized uptake value (SUV) metrics in classifying patients with suspected transthyretin cardiac amyloidosis (ATTR-CA) among the different Perugini grades.

SUBJECTS AND METHODS

One hundred four patients suspected of ATTR-CA underwent planar scintigraphy with bone seeking tracer (99mTc pyrophosphate-PYP). Patients were classified according to the Perugini scale, the H/CL, H/Bone and H/Bkg ratios. A subset of 48 patients received additional SPECT/CT. Single photon emission computed tomography/CT SUV quantitative parameters, of the heart, myocardium, lungs, liver, soft tissues, bone, and SUV ratios (SUVmaxmyo, SUVmaxlungs, SUVmaxliver, SUVmaxbone and SUVmaxsoft tissue ratios), were evaluated in order to investigate potential metrics that could more clearly differentiate Perugini grades.

RESULTS

A total of 33.7% of patients were considered grade 0, 34.6% grade 1 and 31.7% grade 2/3. A combination of H/CL >1.33 and H/Bone >0.85 showed the highest sensitivity 100%. Standardized uptake value-based metrics clearly differentiated grade 0 or 1 vs grades 2 or 3, whereas no significant difference was found between grades 0 and 1, or between grades 1 and 2. The combined cut-off values H/CL 1.33 and SUVmaxmyo 2.88 yielded 100% sensitivity and 84.6% specificity in differentiating ATTR-CA positives vs negatives. The metric SUVmaxmyo/SUVmaxliver was the best metric to classify patients with grade 1 as negative (grade 0) or positive (grade 2 or 3).

CONCLUSION

Single photon emission computed tomography/CT SUV metrics could be complementary to planar scintigraphy in classifying patients among the different Perugini grades. The ratio SUVmaxmyo/SUVmaxliver was the only parameter with high affinity to differentiate patients with grade 1, as grade 0 or grade 2/3 for ATTR-CA.

IL-6 Enhances the Negative Impact of Cortisol on Cognition among Community-Dwelling Older People without Dementia

There is growing evidence that high basal cortisol levels and systemic inflammation independently contribute to cognitive decline among older people without dementia. The present cross-sectional study examined (a) the potential synergistic effect of cortisol levels and systemic inflammation on executive function and (b) whether this effect is more prominent among older people with mild cognitive impairment (MCI). A sub-sample of 99 patients with MCI and 84 older people without cognitive impairment (CNI) (aged 73.8 ± 7.0 years) were recruited from a large population-based cohort in Crete, Greece, and underwent comprehensive neuropsychiatric and neuropsychological evaluation and a single morning measurement of cortisol and IL-6 plasma levels. Using moderated regression models, we found that the relation between cortisol and executive function in the total sample was moderated by IL-6 levels (b = −0.994, p = 0.044) and diagnostic group separately (b = −0.632, p < 0.001). Moreover, the interaction between cortisol and IL-6 levels was significant only among persons with MCI (b = −0.562, p < 0.001). The synergistic effect of stress hormones and systemic inflammation on cognitive status appears to be stronger among older people who already display signs of cognitive decline. Targeting hypercortisolemia and inflammation may be a promising strategy toward improving the course of cognitive decline.

Study of Alzheimer's disease- and frontotemporal dementia-associated genes in the Cretan Aging Cohort

Using exome sequencing, we analyzed 196 participants of the Cretan Aging Cohort (CAC; 95 with Alzheimer's disease [AD], 20 with mild cognitive impairment [MCI], and 81 cognitively normal controls). The APOE ε4 allele was more common in AD patients (23.2%) than in controls (7.4%; p < 0.01) and the PSEN2 p.Arg29His and p.Cys391Arg variants were found in 3 AD and 1 MCI patient, respectively. Also, we found the frontotemporal dementia (FTD)-associated TARDBP gene p.Ile383Val variant in 2 elderly patients diagnosed with AD and in 2 patients, non CAC members, with the amyotrophic lateral sclerosis/FTD phenotype. Furthermore, the p.Ser498Ala variant in the positively selected GLUD2 gene was less frequent in AD patients (2.11%) than in controls (16%; p < 0.01), suggesting a possible protective effect. While the same trend was found in another local replication cohort (n = 406) and in section of the ADNI cohort (n = 808), this finding did not reach statistical significance and therefore it should be considered preliminary. Our results attest to the value of genetic testing to study aged adults with AD phenotype.

Personalized screening and risk profiles for Mild Cognitive Impairment via a Machine Learning Framework: Implications for general practice

OBJECTIVES

Diagnosis of Mild Cognitive Impairment (MCI) requires lengthy diagnostic procedures, typically available at tertiary Health Care Centers (HCC). This prospective study evaluated a flexible Machine Learning (ML) framework toward identifying persons with MCI or dementia based on information that can be readily available in a primary HC setting.

METHODS

Demographic and clinical data, informant ratings of recent behavioral changes, self-reported anxiety and depression symptoms, subjective cognitive complaints, and Mini Mental State Examination (MMSE) scores were pooled from two aging cohorts from the island of Crete, Greece (N = 763 aged 60-93 years) comprising persons diagnosed with MCI (n = 277) or dementia (n = 153), and cognitively non-impaired persons (CNI, n = 333). A Balanced Random Forest Classifier was used for classification and variable importance-based feature selection in nested cross-validation schemes (CNI vs MCI, CNI vs Dementia, MCI vs Dementia). Global-level model-agnostic analyses identified predictors displaying nonlinear behavior. Local level agnostic analyses pinpointed key predictor variables for a given classification result after statistically controlling for all other predictors in the model.

RESULTS

Classification of MCI vs CNI was achieved with improved sensitivity (74 %) and comparable specificity (73 %) compared to MMSE alone (37.2 % and 94.3 %, respectively). Additional high-ranking features included age, education, behavioral changes, multicomorbidity and polypharmacy. Higher classification accuracy was achieved for MCI vs Dementia (sensitivity/specificity = 87 %) and CNI vs Dementia (sensitivity/specificity = 94 %) using the same set of variables. Model agnostic analyses revealed notable individual variability in the contribution of specific variables toward a given classification result.

CONCLUSIONS

Improved capacity to identify elderly with MCI can be achieved by combining demographic and medical information readily available at the PHC setting with MMSE scores, and informant ratings of behavioral changes. Explainability at the patient level may help clinicians identify specific predictor variables and patient scores to a given prediction outcome toward personalized risk assessment.

Alzheimer's disease research progress in the Mediterranean region: The Alzheimer's Association International Conference Satellite Symposium

As research and services in the Mediterranean region continue to increase, so do opportunities for global collaboration. To support such collaborations, the Alzheimer's Association was due to hold its seventh Alzheimer's Association International Conference Satellite Symposium in Athens, Greece in 2021. Due to the COVID-19 pandemic, the meeting was held virtually, which enabled attendees from around the world to hear about research efforts in Greece and the surrounding Mediterranean countries. Research updates spanned understanding the biology of, treatments for, and care of people with Alzheimer's disease (AD_ and other dementias. Researchers in the Mediterranean region have outlined the local epidemiology of AD and dementia, and have identified regional populations that may expedite genetic studies. Development of biomarkers is expected to aid early and accurate diagnosis. Numerous efforts have been made to develop culturally specific interventions to both reduce risk of dementia, and to improve quality of life for people living with dementia.

High Hereditary Transthyretin-Related Amyloidosis Prevalence in Crete

Background and Objectives

Our goal was to study hereditary transthyretin-related amyloidosis (hATTR) in Crete, Greece.

Methods

We aimed at ascertaining all hATTR cases in Crete, an island of 0.62 million people. For this, we evaluated patients with polyneuropathy, autonomic involvement, cardiomyopathy, and/or ophthalmopathy suggestive of hATTR, who presented to the physicians of this study or were referred to them by other physicians. Genetic analyses were performed on all patients suspected of suffering from hATTR. We included in our observational longitudinal cohort study all individuals, residents of Crete, who, during the study period (1993–2019), were found to carry a pathogenic TTR variant.

Results

Over the past 27 years, 30 individuals (15 female patients, 15 male patients), from 12 apparently unrelated families, were diagnosed with hATTR, whereas evaluation of their offspring identified 5 asymptomatic TTR pathogenic variant carriers. The most prevalent TTR variant detected was p.Val50Met, affecting 19 patients (11 female patients, 8 male patients) and causing a rather consistent phenotype characterized by predominant polyneuropathy of early adult onset (median age of symptom onset: 30 years; range: 18–37 years). Specifically, patients affected by the p.Val50Met TTR variant experienced progressive sensorimotor disturbances, involving mainly the lower extremities, associated with autonomic and/or gastrointestinal dysfunction. The second most frequent TTR variant was p.Val114Ala, found in 10 patients (4 female patients, 6 male patients) who were affected at an older age (median age of symptom onset: 70 years; range: 54–78 years). This variant caused a predominantly cardiomyopathic phenotype, manifested by congestive heart failure and associated with peripheral neuropathy, carpal tunnel syndrome, and/or autonomic involvement. In these patients, cardiac amyloid deposition was detected on 99m-technetium pyrophosphate scintigraphy and/or heart biopsy. The third TTR variant (p.Arg54Gly) was found in a 50-year-old male patient with ophthalmopathy due to vitreous opacities and positive family history for visual loss. As 22 patients were alive at the end of the study, we calculated the hATTR prevalence in Crete to be 35 cases per 1 million inhabitants.

Discussion

Our study revealed that the prevalence of hATTR in Crete is one of the world's highest. Three different pathogenic TTR variants causing distinct clinical phenotypes were identified in this relatively small population pool.

Dent-2 disease with a Bartter-like phenotype caused by the Asp631Glu mutation in the OCRL gene

BACKGROUND

Dent disease is an X-linked disorder characterized by low molecular weight proteinuria (LMWP), hypercalciuria, nephrolithiasis and chronic kidney disease (CKD). It is caused by mutations in the chloride voltage-gated channel 5 (CLCN5) gene (Dent disease-1), or in the OCRL gene (Dent disease-2). It is associated with chronic metabolic acidosis; however metabolic alkalosis has rarely been reported.

CASE PRESENTATION

We present a family with Dent-2 disease and a Bartter-like phenotype. The main clinical problems observed in the proband included a) primary phosphaturia leading to osteomalacia and stunted growth; b) elevated serum calcitriol levels, leading to hypercalcemia, hypercalciuria, nephrolithiasis and nephrocalcinosis; c) severe salt wasting causing hypotension, hyperaldosteronism, hypokalemia and metabolic alkalosis; d) partial nephrogenic diabetes insipidus attributed to hypercalcemia, hypokalemia and nephrocalcinosis; e) albuminuria, LMWP. Phosphorous repletion resulted in abrupt cessation of hypercalciuria and significant improvement of hypophosphatemia, physical stamina and bone histology. Years later, he presented progressive CKD with nephrotic range proteinuria attributed to focal segmental glomerulosclerosis (FSGS). Targeted genetic analysis for several phosphaturic diseases was unsuccessful. Whole Exome Sequencing (WES) revealed a c.1893C > A variant (Asp631Glu) in the OCRL gene which was co-segregated with the disease in male family members.

CONCLUSIONS

We present the clinical characteristics of the Asp631Glu mutation in the OCRL gene, presenting as Dent-2 disease with Bartter-like features. Phosphorous repletion resulted in significant improvement of all clinical features except for progressive CKD. Angiotensin blockade improved proteinuria and stabilized kidney function for several years.

Consensus statement on enzyme replacement therapy for mucopolysaccharidosis IVA in Central and South-Eastern European countries

BACKGROUND

Mucopolysaccharidosis IVA (MPS IVA), or Morquio A syndrome, is a rare inherited metabolic disorder caused by deficiency of the lysosomal enzyme N-acetylgalactosamine-6-sulfatase. A progressive systemic skeletal chondrodysplasia, leading to significant morbidity and reduced life expectancy is the main clinical feature of this multisystemic disease. Although enzyme replacement therapy with elosulfase alfa is established in Europe, the rarity of disease and other factors still set hurdles in having patients treated in some countries. Aim of this statement is to provide evidence-based guidance for the enzyme replacement treatment of Morquio A patients, harmonizing recommendations from published guidelines with the real-life clinical practice in the Central and South-Eastern European region.

PARTICIPANTS

The Consensus Group, convened by 8 Steering Committee (SC) members from 7 Central and South-Eastern European countries, consisted of a multidisciplinary group of 17 experts in the management of MPS in Central and South-Eastern Europe.

CONSENSUS PROCESS

The SC met in a first virtual meeting with an external scientific coordinator, to discuss on clinical issues to be analyzed in guidance statements. Statements were developed by the scientific coordinator, evaluated by the SC members in a first modified-Delphi voting and adapted accordingly, to be submitted to the widest audience in the Consensus Conference. Following discussion and further modifications, all participants contributed to a second round of modified-Delphi voting.

RESULTS

Nine of ten statements, concerning general guidelines for management of MPS IVA patients and specific recommendations for treatment, received final consensus.

CONCLUSIONS

European guidelines and evidence-based recommendations for Morquio A patients should be considered in the real life of Central and South-Eastern European countries and adapted to unique clinical practice approaches and criteria for patients' access to treatment and reimbursement in the region.

The landscape of Mucopolysaccharidosis in Southern and Eastern European countries: a survey from 19 specialistic centers

Background

Mucopolysaccharidoses (MPS) are a group of lysosomal storage disorders caused by defects in genes coding for different lysosomal enzymes which degrade glycosaminoglycans. Impaired lysosomal degradation causes cell dysfunction leading to progressive multiorgan involvement, disabling consequences and poor life expectancy. Enzyme replacement therapy (ERT) is now available for most MPS types, offering beneficial effects on disease progression and improving quality of life of patients. The landscape of MPS in Europe is not completely described and studies on availability of treatment show that ERT is not adequately implemented, particularly in Southern and Eastern Europe. In this study we performed a survey analysis in main specialist centers in Southern and Eastern European countries, to outline the picture of disease management in the region and understand ERT implementation. Since the considerable number of MPS IVA patients in the region, particularly adults, the study mainly focused on MPS IVA management and treatment.

Results

19 experts from 14 Southern and Eastern European countries in total responded to the survey. Results outlined a picture of MPS management in the region, with a high number of MPS patients managed in the centers and a high level of care. MPS II was the most prevalent followed by MPS IVA, with a particular high number of adult patients. The study particularly focused on management and treatment of MPS IVA patients. Adherence to current European Guidelines for follow-up of MPS IVA patients is generally adequate, although some important assessments are reported as difficult due to the lack of MPS skilled specialists. Availability of ERT in Southern and Eastern European countries is generally in line with other European regions, even though regulatory, organizational and reimbursement constrains are demanding.

Conclusions

The landscape of MPS in Southern and Eastern European countries is generally comparable to that of other European regions, regarding epidemiology, treatment accessibility and follow up difficulties. However, issues limiting ERT availability and reimbursement should be simplified, to start treatment as early as possible and make it available for more patients. Besides, educational programs dedicated to specialists should be implemented, particularly for pediatricians, clinical geneticists, surgeons, anesthesiologists and neurologists.

Interactions of Mediterranean Diet, Obesity, Polypharmacy, Depression and Systemic Inflammation with Frailty Status

Objective:Comprehensive characterization of potential frailty determinants, including sociodemographic, clinical, dietary, psychological, cognitive and systemic inflammation parameters. Methods:A rural cohort of 186 subjects aged 60-89 years recruited from a community-based study in Crete, Greece (the Cretan Aging Cohort). Frailty was assessed with the Simple "Frail" Questionnaire Screening Tool. Results:Univariate analyses revealed significant (a) positive associations (p<0.01) between frailty and age, widowhood, Geriatric Depression Scale (GDS) score, waist circumference, polypharmacy, IL-6 and (b) negative associations between frailty and frequency of contact with friends, Mini Mental State Examination (MMSE), and adherence to the Mediterranean diet. Multivariate analyses revealed a significant independent contribution of the following variables to frailty: age (B=0.035, p<0.001), GDS score (B=0.041, p=0.034), polypharmacy (B=0.568, p<0.001), waist circumference (B=0.015, p=0,006), plasma IL-6 levels (B=0.189, p=0.004), and adherence to the Mediterranean diet (B=-0.036, p=0.015). Conclusion:Older age, depression symptoms, polypharmacy, waist circumference, poor adherence to Mediterranean diet and IL-6 plasma levels are associated with increased frailty.

Specific characteristics and current diagnostic and treatment modalities performance of super refractory status epilepticus in children: A comparative study

OBJECTIVE

Super-refractory status epilepticus (SRSE) is associated with significant morbidity and mortality in children. We explored the clinical spectrum, specific characteristics, and outcome in SRSE patients admitted in a pediatric intensive care unit (PICU) and investigated how well current diagnostic or treatment modalities perform compared to Status Epilepticus (SE) and Refractory SE (RSE) patients.

METHODS

Retrospective analysis of PICU patients admitted with convulsive SE during 2009-2019. Eighty-six patients were classified as SE, RSE, and SRSE. New-onset RSE (NORSE) and febrile infection-related epilepsy syndrome (FIRES) were also identified. Functional outcome was evaluated by the modified Rankin scale.

RESULTS

Patients with SRSE (n = 20) had longer weaning off anesthetics (p = 0.014), length of stay, mechanical ventilation duration, higher illness severity scores, and poorer outcome compared to SE (n = 13) or RSE (n = 53) patients (all p < 0.001). Diagnosis, mainly expressed by high prevalence of NORSE (n = 13) and FIRES (n = 9), was independently associated with SRSE (p = 0.024). Abnormal MRI findings (p = 0.005), and epilepsy-related pathogenic variants identified by whole-exome sequencing (WES) were mostly found in SRSE patients. Compared to intravenous immunoglobulins and steroid pulses, plasmapheresis and ketogenic diet, more often used in SRSE (p < 0.01), contributed better to seizure control. Only SRSE (AUROC > 0.80, 95% CI = 0.68-0.94, p < 0.001) and diagnosis (AUROC > 0.70, 95% CI = 0.55-0.83, p = 0.02) could predict a poor outcome.

CONCLUSION

The majority of SRSE patients are characterized by considerable functional decline and morbidity. WES analysis may reveal epilepsy-related pathogenic variants while early aggressive immunotherapy and/or ketogenic diet might prove beneficial. Multicenter studies for prediction models of outcome are needed.

The association of basal cortisol levels with episodic memory in older adults is mediated by executive function

Elevated basal cortisol levels in elderly may indicate dysregulation of the internal stress-related system, as well as dysfunction and structural alterations in brain structures necessary for cognition, such as hippocampus and prefrontal cortex. Because of the close relation of executive functions and episodic memory processing, in this study we explored whether the association of elevated cortisol levels on episodic memory could be partly attributed to cortisol effects on executive functions. In this cross-sectional study we analyzed data from a sample of 236 community-dwelling older adults from the Cretan Aging Cohort aged 75.56 ± 7.21 years [53 with dementia due to probable Alzheimer's disease, 99 with Mild Cognitive Impairment (MCI) and 84 cognitively non-impaired participants (NI)]. Morning serum cortisol levels were higher in the probable AD as compared to the NI group (p = .031). Mediated regression models in the total sample supported the hypothesis that the negative association of basal cortisol levels with delayed memory was fully mediated by the relation of basal cortisol levels with executive functions and immediate memory (adjusted for age and self-reported depression symptoms). Moderated mediation regression models revealed that the direct effect of cortisol on executive function and the effect of executive function on delayed memory performance were statistically significant among participants diagnosed with MCI, while the immediate memory effect on delayed memory was more pronounced in AD patients, as compared to the NI group. The current findings corroborate neuroimaging research highlighting cortisol effects on executive functions and immediate memory and further suggest that dysregulation of systems involved in these functions may account for the purported detrimental long-term effects of high cortisol levels on delayed memory.

Poor Diet, Long Sleep, and Lack of Physical Activity Are Associated with Inflammation among Non-Demented Community-Dwelling Elderly

Inflammation in elderly is associated with physical and cognitive morbidity and mortality. We aimed to explore the association of modifiable lifestyle parameters with inflammation among non-demented, community-dwelling elderly. A sub-sample of 117 patients with mild cognitive impairment (MCI, n = 63) and cognitively non-impaired controls (CNI, n = 54) were recruited from a large, population-based cohort in Crete, Greece, of 3140 elders (>60 years old). All participants underwent assessment of medical history/physical examination, extensive neuropsychiatric/neuropsychological evaluation, diet, three-day 24-h actigraphy, subjective sleep, physical activity, and measurement of IL-6 and TNFα plasma levels. Associations between inflammatory markers and diet, objective sleep duration, subjective sleep quality, and lack of physical activity were assessed using multivariate models. Regression analyses in the total group revealed significant associations between TNF-α and low vegetable consumption (p = 0.003), and marginally with objective long nighttime sleep duration (p = 0.04). In addition, IL-6 was associated with low vegetable consumption (p = 0.001) and lack of physical activity (p = 0.001). Poor diet and lack of physical activity appear to be modifiable risk factors of inflammation, whereas long sleep appears to be a marker of increased inflammatory response in elderly. Our findings may have clinical implications given the association of inflammatory response with morbidity, including cognitive decline, and mortality in elderly.

Basal Cortisol Levels Are Increased in Patients with Mild Cognitive Impairment: Role of Insomnia and Short Sleep Duration

BACKGROUND

Mild cognitive impairment (MCI) is frequent in elderly and a risk factor for dementia. Both insomnia and increased cortisol levels are risk factors for MCI.

OBJECTIVE

We examined cross-sectionally whether increased cortisol levels are associated with short sleep duration (SSD) and/or the insomnia short sleep duration (ISS) phenotype, in elderly with MCI.

METHODS

One hundred twenty-four participants with MCI and 84 cognitively non-impaired controls (CNI)≥60 years underwent medical history, physical examination, neuropsychiatric evaluation, neuropsychological testing, 3-day actigraphy, assessment of subjective insomnia symptoms, and a single morning plasma cortisol level. The short sleep phenotypes were defined by sleep efficiency below the median of the entire sample (i.e.,≤81%) with at least one insomnia symptom (ISS) or without (SSD). ANOVA models were used to compare the various sleep phenotypes to those who did not present either short sleep or insomnia symptoms [non-insomnia (NI)].

RESULTS

MCI participants had higher cortisol levels compared to the CNI group (p = 0.009). MCI participants with insomnia (n = 44) or SSD (n = 38) had higher cortisol levels compared to the NI group (n = 42; p = 0.014 and p = 0.045, respectively). Furthermore, MCI participants with ISS phenotype but not those with insomnia with normal sleep duration had higher cortisol levels compared to NI (p = 0.011 and p = 0.4, respectively). Both linear trend analyses showed that cortisol reached the highest levels in the ISS phenotype.

CONCLUSION

The ISS and SSD phenotypes are associated with increased cortisol levels in elderly with MCI. Improving sleep quality and duration and decreasing cortisol levels may delay further cognitive decline.

Variant transthyretin amyloidosis (ATTRv) polyneuropathy in Greece: a broad overview with a focus on non-endemic unexplored regions of the country

Comprehensive data on variant transthyretin amyloidosis polyneuropathy (ATTRv-PN) in Greece are lacking. We presently provide an overview of ATTRv-PN in Greece, focusing on unexplored non-endemic regions of the country. In total, we identified 57 cases of ATTRv-PN diagnosed over the past 25 years, including 30 from the island of Crete, an apparent endemic region. Patients carried 10 different TTR mutations (C10R; P24S; V30M; R34G; R34T; I68L; A81T; E89Q; E89K and V94A). Carriers of the common V30M mutation constituted 54.3 % of the cohort. A known founder effect for the V30M mutation was present on the island of Crete. Non-endemic cases identified outside the island of Crete are presently reported in more detail. The age of onset ranged from 25 to 77 years, with a mean of 51.1 years. A mean diagnostic delay of 3.2 years was observed. V30M patients had earlier onset and less cardiac involvement than patients carrying other mutations. Genotype-phenotype correlations were largely consistent with published data. We conclude that, with the exception of the Cretan cluster, ATTRv-PN is not endemic in the Greek population. This makes timely diagnosis more challenging, yet absolutely essential given the availability of therapies that can alter the long-term course of the disease.

Genotyping and Plasma/Cerebrospinal Fluid Profiling of a Cohort of Frontotemporal Dementia-Amyotrophic Lateral Sclerosis Patients

Frontotemporal dementia (FTD) and amyotrophic lateral sclerosis (ALS) are part of the same pathophysiological spectrum and have common genetic and cerebrospinal fluid (CSF) biomarkers. Our aim here was to identify causative gene variants in a cohort of Greek patients with FTD, ALS and FTD-ALS, to measure levels of CSF biomarkers and to investigate genotype-phenotype/CSF biomarker associations. In this cohort of 130 patients (56 FTD, 58 ALS and 16 FTD-ALS), we performed C9orf72 hexanucleotide repeat expansion analysis, whole exome sequencing and measurement of “classical” (Aβ₄₂, total tau and phospho-tau) and novel (TDP-43) CSF biomarkers and plasma progranulin. Through these analyses, we identified 14 patients with C9orf72 repeat expansion and 11 patients with causative variants in other genes (three in TARDBP, three in GRN, three in VCP, one in FUS, one in SOD1). In ALS patients, we found that levels of phospho-tau were lower in C9orf72 repeat expansion and MAPT c.855C>T (p.Asp285Asp) carriers compared to non-carriers. Additionally, carriers of rare C9orf72 and APP variants had lower levels of total tau and Aβ₄₂, respectively. Plasma progranulin levels were decreased in patients carrying GRN pathogenic variants. This study expands the genotypic and phenotypic spectrum of FTD/ALS and offers insights in possible genotypic/CSF biomarker associations.

A novel variant in DYNC1H1 could contribute to human amyotrophic lateral sclerosis-frontotemporal dementia spectrum

Amyotrophic lateral sclerosis (ALS) belongs to the ALS-frontotemporal dementia (FTD) spectrum and is hallmarked by upper and lower motor neuron degeneration. Here, we present a patient with a cytoplasmic dynein 1 heavy chain 1 (DYNC1H1) pathogenic variant who fulfilled the ALS El Escorial criteria, and we review relevant literature. Using whole-exome sequencing, we identified a deleterious point variant in DYNC1H1 (c.4106A > G (p. Q1369R)) as a likely contributor to the ALS phenotype. In silico structural analysis, molecular dynamics simulation, and protein stability analysis predicted that this variant may increase DYNC1H1 protein stability. Moreover, this variant may disrupt binding of the transcription factor TFAP4, thus potentially acting as duon. Because (a) DYNC1H1 forms part of a ubiquitous eukaryotic motor protein complex, and (b) disruption of dynein function by perturbation of the dynein–dynactin protein complex is implicated in other motor neuron degenerative conditions, this variant could disrupt processes like retrograde axonal transport, neuronal migration, and protein recycling. Our findings expand the heterogenous spectrum of the DYNC1H1 pathogenic variant−associated phenotype and prompt further investigations of the role of this gene in ALS.

Genetic cause of epilepsy in a Greek cohort of children and young adults with heterogeneous epilepsy syndromes

We describe a cohort of 10 unrelated Greek patients (4 females, 6 males; median age 6.5 years, range 2-18 years) with heterogeneous epilepsy syndromes with a genetic basis. In these patients, causative genetic variants, including two novel ones, were identified in 9 known epilepsy-related genes through whole exome sequencing. A patient with glycine encephalopathy was a compound heterozygote for the p.Arg222Cys and the p.Ser77Leu AMT variant. A patient affected with Lafora disease carried the homozygous p.Arg171His EPM2A variant. A de novo heterozygous variant in the GABRG2 gene (p.Pro282Thr) was found in one patient and a pathogenic variant in the GRIN2B gene (p.Gly820Val) in another patient. Infantile-onset lactic acidosis with seizures was associated with the p.Arg446Ter PDHX gene variant in one patient. In two additional epilepsy patients, the p.Ala1662Val and the novel non-sense p.Phe1330Ter SCN1A gene variants were found. Finally, in 3 patients we observed a novel heterozygous missense variant in SCN2A (p.Ala1874Thr), a heterozygous splice site variant in SLC2A1 (c.517-2A>G), as a cause of Glut1 deficiency syndrome, and a pathogenic variant in STXBP1 (p.Arg292Leu), respectively. In half of our cases (patients with variants in the GRIN2B, SCN1A, SCN2A and SLC2A1 genes), a genetic cause with potential management implications was identified.

369 Insomnia with objective short sleep duration is associated with increased cortisol in patients with Mild Cognitive Impairment

Introduction

Mild cognitive impairment (MCI) is frequent in the elderly and is in a continuum with dementia in a significant amount of people. Both insomnia and increased cortisol levels have been suggested as risk factors for MCI. The goal of this study was to examine whether activation of the hypothalamic-pituitary-adrenal (HPA) axis, as measured by plasma cortisol levels, is associated with the insomnia with short sleep duration (ISS) phenotype, as measured by actigraphy, in elderly with MCI.

Methods

A sub-sample of 109 subjects with MCI and 92 cognitively non-impaired controls 60 years or older (75.37±6.54y) was recruited from a population-based cohort residing on Crete, Greece. Subjects underwent medical history, physical examination, neuropsychiatric evaluation, neuropsychological testing, 3-day 24-h actigraphy, assessment of subjective insomnia symptoms (i.e., difficulties initiating and/or maintaining sleep), and a morning blood draw to assay for plasma cortisol levels. The ISS phenotype was defined by the presence of at least one insomnia symptom and an actigraphy-measured sleep efficiency below the median of the entire sample (i.e., ≤81%). Group differences in plasma cortisol levels between MCI subjects with and without the ISS phenotype were tested using ANCOVA adjusting for age, gender, BMI and depression.

Results

Subjects with MCI had higher cortisol levels compared to controls (105.34±9.34 vs. 70.3±10.02 nmol/L, p&lt;0.05). Subjects with MCI and the ISS phenotype (138.38±16.57 nmol/L) had significantly higher cortisol levels compared to those without insomnia (97.74±19.68 nmol/L) or those with insomnia and normal sleep duration (INS; 79.97±16.02 nmol/L, p=0.044). The association between the ISS phenotype and cortisol levels was modified by amnestic symptoms (p-interaction=0.079); commensurate, the ISS phenotype was associated with higher cortisol levels among the amnestic MCI subgroup (INS: 79.12±21.93 vs. ISS: 155.55±20.40 nmol/L, p=0.040), but not among the non-amnestic MCI subgroup (INS: 64.06±23.62 vs. ISS: 89.33±29.00 nmol/L, p=0.559).

Conclusion

The ISS phenotype is associated with increased cortisol levels in elderly with MCI, particularly those with amnestic type. Improving sleep quality, decreasing cortisol levels and lengthening sleep duration may slow down the progression of these individuals into dementia.

Support (if any)

National Strategic Reference Framework(NSRF), Program: THALES entitled “UOC-Multidisciplinary network for the study of Alzheimer’s Disease” Grant Cod:MIS 377299

Objective Daytime Napping is Associated with Disease Severity and Inflammation in Patients with Mild to Moderate Dementia1

BACKGROUND

Patients with dementia report excessive daytime sleep/sleepiness, which is associated with worse cognitive performance. Inflammatory markers may be elevated in patients with dementia and have been proposed as mediators of sleep/sleepiness.

OBJECTIVE

To examine the association of objective daytime napping with cognitive performance and peripheral markers of inflammation in patients with dementia as compared to not cognitively impaired (NCI) controls.

METHODS

A sub-sample of 46 patients with mild-to-moderate dementia and 85 NCI controls, were recruited from a large, population-based cohort of 3,140 elders (≥60 years) in Crete, Greece. All participants underwent medical history/physical examination, extensive neuropsychiatric and neuropsychological evaluation, 3-day 24 h actigraphy and a single morning measure of IL-6 and TNFα plasma levels. Comparisons of sleep parameters and inflammation markers between diagnostic groups, and between nappers and non-nappers within each diagnostic group, were conducted using ANCOVA controlling for demographics/related clinical factors. Associations between inflammatory markers, sleep variables, and neuropsychological performance were assessed within each group using partial correlation analysis controlling for confounders.

RESULTS

Patients with dementia slept 15 minutes longer during the day than NCI. Within dementia patients, nappers had significantly worse performance on autobiographic memory (p = 0.002), working memory (p = 0.007), episodic memory (p = 0.010), and assessment of daily function (p = 0.012) than non-nappers. Finally, IL-6 levels were significantly associated with nap duration within dementia patients who napped (r = 0.500, p = 0.01).

CONCLUSIONS

Daytime napping in patients with dementia is associated with worse cognitive performance and increased IL-6 levels. In dementia, objective daytime napping, may be a marker of the severity of the disease.

Evidence of Age-Related Hemodynamic and Functional Connectivity Impairment: A Resting State fMRI Study

Purpose: To assess age-related changes in intrinsic functional brain connectivity and hemodynamics during adulthood in the context of the retrogenesis hypothesis, which states that the rate of age-related changes is higher in late-myelinating (prefrontal, lateral-posterior temporal) cerebrocortical areas as compared to early myelinating (parietal, occipital) regions. In addition, to examine the dependence of age-related changes upon concurrent subclinical depression symptoms which are common even in healthy aging. Methods: Sixty-four healthy adults (28 men) aged 23-79 years (mean 45.0, SD = 18.8 years) were examined. Resting-state functional MRI (rs-fMRI) time series were used to compute voxel-wise intrinsic connectivity contrast (ICC) maps reflecting the strength of functional connectivity between each voxel and the rest of the brain. We further used Time Shift Analysis (TSA) to estimate voxel-wise hemodynamic lead or lag for each of 22 ROIs from the automated anatomical atlas (AAL). Results: Adjusted for depression symptoms, gender and education level, reduced ICC with age was found primarily in frontal, temporal regions, and putamen, whereas the opposite trend was noted in inferior occipital cortices (p < 0.002). With the same covariates, increased hemodynamic lead with advancing age was found in superior frontal cortex and thalamus, with the opposite trend in inferior occipital cortex (p < 0.002). There was also evidence of reduced coupling between voxel-wise intrinsic connectivity and hemodynamics in the inferior parietal cortex. Conclusion: Age-related intrinsic connectivity reductions and hemodynamic changes were demonstrated in several regions-most of them part of DMN and salience networks-while impaired neurovascular coupling was, also, found in parietal regions. Age-related reductions in intrinsic connectivity were greater in anterior as compared to posterior cortices, in line with implications derived from the retrogenesis hypothesis. These effects were affected by self-reported depression symptoms, which also increased with age.

Crystal structure of glutamate dehydrogenase 2, a positively selected novel human enzyme involved in brain biology and cancer pathophysiology

INTRODUCTION

Mammalian glutamate dehydrogenase (hGDH1 in human cells) interconverts glutamate to α-ketoglutarate and ammonia while reducing NAD(P) to NAD(P)H. During primate evolution, humans and great apes have acquired hGDH2, an isoenzyme that underwent rapid evolutionary adaptation concomitantly with brain expansion, thereby acquiring unique catalytic and regulatory properties that permitted its function under conditions inhibitory to its ancestor hGDH1. Although the 3D-structures of GDHs, including hGDH1, have been determined, attempts to determine the hGDH2 structure were until recently unsuccessful. Comparison of the hGDH1/hGDH2 structures would enable a detailed understanding of their evolutionary differences. This work aimed at the determination of the hGDH2 crystal structure and the analysis of its functional implications. Recombinant hGDH2 was produced in the Spodoptera frugiperda ovarian cell line Sf21, using the Baculovirus expression system. Purification was achieved via a two-step chromatography procedure. hGDH2 was crystallized, X-ray diffraction data were collected using synchrotron radiation and the structure was determined by molecular replacement. The hGDH2 structure is reported at a resolution of 2.9 Å. The enzyme adopts a novel semi-closed conformation, which is an intermediate between known open and closed GDH1 conformations, differing from both. The structure enabled us to dissect previously reported biochemical findings and to structurally interpret the effects of evolutionary amino acid substitutions, including Arg470His, on ADP affinity. In conclusion, our data provide insights into the structural basis of hGDH2 properties, the functional evolution of hGDH isoenzymes, and open new prospects for drug design, especially for cancer therapeutics.

Apolipoprotein E ɛ4 (APOE ɛ4) Allele is Associated with Long Sleep Duration Among Elderly with Cognitive Impairment

Background: Apolipoprotein E gene (APOE) ɛ4 allele increases the risk for Alzheimer’s disease (AD). Furthermore, among patients with cognitive impairment, longer sleep duration is associated with worse cognitive performance. To date, literature examining the associations between APOE ɛ4 allele and objective sleep duration is limited. Objective: Our aim was to assess the association between APOE ɛ4 and objective sleep duration, among patients with mild cognitive impairment (MCI) and AD. A sub-sample of 89 patients with AD (n = 49) and MCI (n = 40) were recruited from a large, population-based cohort of 3,140 elders (>60 years) residing on Crete, Greece. Methods: All participants underwent medical history/physical examination, extensive neuropsychiatric and neuropsychological evaluation, 3-day 24 h actigraphy and APOE ɛ4 allele genotyping. Comparisons of sleep duration variables between APOE ɛ4 allele carriers and non-carriers were assessed using ANCOVA, controlling for confounders. Results: The sample included 18 APOE ɛ4 carriers and 71 non-carriers, aged 78.6±6.6 and 78.2±6.5 years, respectively. Comparisons between the APOE ɛ4 carriers and non-carriers revealed no significant differences in terms of demographic and clinical variables. In terms of objective sleep duration across the two groups, APOE ɛ4 carriers compared to non-carriers had significantly longer nighttime Total Sleep Time (nTST) (7.7±1.4 versus 7.2±1.3  h, respectively, p = 0.011), as well as 24 h TST (8.5±1.6 versus 7.8±1.5  h, respectively, p = 0.012). Conclusion: Among patients with MCI and AD, APOE ɛ4 carriers have longer objective nighttime and 24 h sleep duration compared to non-carriers. These findings further support that objective long sleep duration is a genetically-driven pre-clinical marker associated with worse prognosis in elderly with cognitive impairment.

Genetic cause of heterogeneous inherited myopathies in a cohort of Greek patients

Inherited muscle disorders are caused by pathogenic changes in numerous genes. Herein, we aimed to investigate the etiology of muscle disease in 24 consecutive Greek patients with myopathy suspected to be genetic in origin, based on clinical presentation and laboratory and electrophysiological findings and absence of known acquired causes of myopathy. Of these, 16 patients (8 females, median 24 years-old, range 7 to 67 years-old) were diagnosed by Whole Exome Sequencing as suffering from a specific type of inherited muscle disorder. Specifically, we have identified causative variants in 6 limb-girdle muscular dystrophy genes (6 patients; ANO5, CAPN3, DYSF, ISPD, LAMA2, SGCA), 3 metabolic myopathy genes (4 patients; CPT2, ETFDH, GAA), 1 congenital myotonia gene (1 patient; CLCN1), 1 mitochondrial myopathy gene (1 patient; MT-TE) and 3 other myopathy-associated genes (4 patients; CAV3, LMNA, MYOT). In 6 additional family members affected by myopathy, we reached genetic diagnosis following identification of a causative variant in an index patient. In our patients, genetic diagnosis ended a lengthy diagnostic process and, in the case of Multiple acyl-CoA dehydrogenase deficiency and Pompe's disease, it enabled specific treatment to be initiated. These results further expand the genotypic and phenotypic spectrum of inherited myopathies.

Cognitive Impairment and Dementia in Primary Care: Current Knowledge and Future Directions Based on Findings From a Large Cross-Sectional Study in Crete, Greece

Introduction: Dementia severely affects the quality of life of patients and their caregivers; however, it is often not adequately addressed in the context of a primary care consultation, especially in patients with multi-morbidity. Study Population and Methods: A cross-sectional study was conducted between March-2013 and December-2014 among 3,140 consecutive patients aged >60 years visiting 14 primary health care practices in Crete, Greece. The Mini-Mental-State-Examination [MMSE] was used to measure cognitive status using the conventional 24-point cut-off. Participants who scored low on MMSE were matched with a group of elders scoring >24 points, according to age and education; both groups underwent comprehensive neuropsychiatric and neuropsychological assessment. For the diagnosis of dementia and Mild-Cognitive-Impairment (MCI), the Diagnostic and Statistical Manual-of-Mental-Disorders (DSM-IV) criteria and the International-Working-Group (IWG) criteria were used. Chronic conditions were categorized according to ICD-10 categories. Logistic regression was used to provide associations between chronic illnesses and cognitive impairment according to MMSE scores. Generalized Linear Model Lasso Regularization was used for feature selection in MMSE items. A two-layer artificial neural network model was used to classify participants as impaired (dementia/MCI) vs. non-impaired. Results: In the total sample of 3,140 participants (42.1% men; mean age 73.7 SD = 7.8 years), low MMSE scores were identified in 645 (20.5%) participants. Among participants with low MMSE scores 344 (54.1%) underwent comprehensive neuropsychiatric evaluation and 185 (53.8%) were diagnosed with Mild-Cognitive-Impairment (MCI) and 118 (34.3%) with dementia. Mental and behavioral disorders (F00-F99) and diseases of the nervous system (G00-G99) increased the odds of low MMSE scores in both genders. Generalized linear model lasso regularization indicated that 7/30 MMSE questions contributed the most to the classification of patients as impaired (dementia/MCI) vs. non-impaired with a combined accuracy of 82.0%. These MMSE items were questions 5, 13, 19, 20, 22, 23, and 26 of the Greek version of MMSE assessing orientation in time, repetition, calculation, registration, and visuo-constructive ability. Conclusions: Our study identified certain chronic illness-complexes that were associated with low MMSE scores within the context of primary care consultation. Also, our analysis indicated that seven MMSE items provide strong evidence for the presence of dementia or MCI.

Cognitive impairment in a primary healthcare population: a cross-sectional study on the island of Crete, Greece

OBJECTIVES

Cognitive impairment is known to have a significant impact on the quality of life of individuals and their caregivers, yet it is often underdiagnosed. The objective of this study is to assess the extent of cognitive impairment among elders visiting primary healthcare (PHC) practice settings, to explore associated risk factors and discuss current care challenges for PHC providers.

DESIGN

A cross-sectional study was conducted between March 2013 and May 2014.

SETTING

Fourteen PHC units located in rural and urban areas of the Heraklion district in Crete, Greece.

PARTICIPANTS

Consecutive visitors aged at least 60 years attending selected PHC practices.

PRIMARY AND SECONDARY OUTCOME MEASURES

The Mini-Mental State Examination (MMSE) was used to indicate cognitive status. Associations of low MMSE scores (≤23/24, adjusted for education level) with 12 socio-demographic factors, comorbidities and lifestyle factors were assessed.

RESULTS

A total of 3140 PHC patients met inclusion criteria (43.2% male; mean age 73.7±7.8 years). The average MMSE score was 26.0±3.8; 26.7±3.5 in male and 25.4±3.9 in female participants (p<0.0001). Low MMSE scores were detected in 20.2% of participants; 25.9% for females vs 12.8% for males; p<0.0001. Female gender (adjusted OR (AOR)=2.72; 95% CI 2.31 to 3.47), age (AOR=1.11; 95% CI 1.10 to 1.13), having received only primary or no formal education (AOR=2.87; 95% CI 2.26 to 3.65), alcohol intake (AOR=1.19; 95% CI 1.03 to 1.37), reporting one or more sleep complaints (AOR 1.63; 95% CI 1.14 to 2.32), dyslipidaemia (AOR=0.80; 95% CI 0.65 to 0.98) and history of depression (AOR=1.90; 95% CI 1.43 to 2.52) were associated with low MMSE scores.

CONCLUSIONS

This study identified a relatively high prevalence of low MMSE scores among persons attending PHC practices in a southern European community setting and associations with several known risk factors.

1120 Inverse U-Curve Association Between Sleep Duration and Cognitive Performance Among Patients with Dementia: Findings From the Cretan Aging Cohort

Introduction

Previous research reports an inverse U-curve association between subjective sleep duration and cognition in elderly, while findings on objective sleep duration are inconsistent. Only one study found weak association between objective short sleep duration and cognition, mainly driven by demented elders. Our aim was to examine the non-linear associations between objective sleep duration and cognitive performance among community-dwelling patients with dementia.

Methods

A sub-sample of 46 patients with mild-to-moderate dementia(AD) [mean age: 80.3 (SD=5.6) years, 40% males] and 85 cognitively intact controls(NI) [mean age: 73.0 (SD=7.4) years, 37% males], were recruited from a large, population-based cohort [Cretan Aging Cohort] in the island of Crete, Greece of 3,140 older adults (≥60yrs). All participants underwent medical history/physical examination, extensive neuropsychiatric and neuropsychological evaluation, and 3-day 24-h actigraphy. Comparisons between AD and NI participants on sleep parameters and neuropsychological performance were made using ANOVA controlling for demographics. Associations between 24-TST, and age- and education-adjusted cognitive scores and Independent Activity of Daily Living Scale (IADL) scores were assessed using hierarchical, non-linear, regression models, controlling for confounders.

Results

Dementia patients had significantly longer 24-h total sleep time (24h-TST) (491.2±107.1 min vs. 444.6±88.5 min, respectively, p=0.027), as well as lower cognitive/IADL sores as compared to the NI group. Significant associations between objective sleep and various cognitive /IADL scores were found only among patients with dementia. Specifically, we found a negative curvilinear association between 24-h TST and IADL, episodic memory indices (AVLT Retention, autobiographic memory) and visuomotor coordination speed (Trail Making Test, Part A).

Conclusion

Our study showed an inverse U-curve association between objective sleep duration and daily function, memory, and executive function in patients with dementia. Possibly, sleep loss may lead to cognitive impairment, whereas, prolonged sleep may be an indicator of worse cognitive performance among patients with dementia.

Support

National Strategic Reference Framework (ESPA) 2007-2013, Program: THALES, University of Crete, title: “A multi-disciplinary network for the study of Alzheimer’s Disease” (Grant: MIS 377299).

1130 Insomnia Short Sleep Phenotype is Associated With Frailty in Patients With Mild Cognitive Impairment (MCI)

Introduction

Insomnia short sleep phenotype is associated with cardiometabolic morbidity and mortality and neuropsychological impairment. In elderly untreated insomnia is associated with worse cognitive performance. The goal of the study was to examine the association between insomnia, objective sleep duration and physical and mental health in elderly patients with Mild Cognitive Impairment (MCI).

Methods

A sub-sample of 105 patients with MCI (mean age: 75.9 years, males 36%) were recruited from a large population-based cohort (Cretan Aging Cohort) in the island of Crete, Greece of 3,140 elders (≥ 60yrs). All participants underwent a complete medical history/ physical examination, extensive neuropsychiatric and neuropsychological evaluation and 3-day 24hr actigraphy. Insomnia was defined based on a question “do you have insomnia for more than a year”. Frailty was assessed with the Simple “Frail” Questionnaire Screening Tool. Comparisons between patients with insomnia and without insomnia were made using ANOVA controlling for age, gender and BMI.

Results

MCI patients with insomnia (n=23) compared to those without insomnia (n=82), had significantly shorter objective total sleep time (TST: 377 vs. 410 min, p=0.05) and significantly higher scores on the Geriatric Depression Scale and the Hospital Anxiety Scale (both p &lt;0.001). Furthermore, total frailty score, as well as scores in individual items, were significantly lower in MCI patients with insomnia (p&lt;0.01). This association remained significant after controlling for demographics, depression and anxiety. Finally, there was a statistical trend of association between insomnia and hypertension (p= 0.1).

Conclusion

In MCI patients, insomnia is associated with objective short sleep duration, and frailty. Improving insomnia and lengthening sleep duration may decrease frailty, a major problem associated with morbidity, disability and mortality in elders with cognitive decline.

Support

National Strategic Reference Framework (ESPA) 2007-2013, Program: THALES, University of Crete, title: “A multi-disciplinary network for the study of Alzheimer’s Disease” (Grant: MIS 377299).

Whole exome sequencing establishes diagnosis of Charcot-Marie-Tooth 4J, 1C, and X1 subtypes

BACKGROUND

Charcot-Marie-Tooth (CMT) hereditary polyneuropathies pose a diagnostic challenge. Our aim here is to describe CMT patients diagnosed by whole exome sequencing (WES) following years of fruitless testing.

METHODS/RESULTS

Three patients with polyneuropathy suspected to be genetic in origin, but not harboring PMP22 gene deletion/duplication, were offered WES. The first patient, a 66-year-old man, had been suffering from progressive weakness and atrophies in the lower and upper extremities for 20 years. Due to ambiguous electrophysiological findings, immune therapies were administered to no avail. Twelve years after PMP22 deletion/duplication testing, WES revealed two pathogenic variants in the FIG4 gene (p.Ile41Thr and p.Phe598fs, respectively), as a cause of CMT 4J. The second patient, a 19-year-old man, had been suffering from hearing and gait impairment since at least his infancy, and recently presented with weakness and dystonia of the lower extremities. In this patient, WES identified the p.Leu122Val LITAF gene variant in heterozygous state, suggesting the diagnosis of CMT 1C, several years after initial genetic analyses. The third patient, a 44-year-old man, presented with progressive weakness and atrophies of the lower and upper extremities since the age of 17 years old. In this patient, WES identified the hemizygous p.Arg164Gln pathogenic variant in the GJB1 gene, establishing the diagnosis of CMT X1, 8 years after testing for PMP22 deletion/duplication.

CONCLUSION

Novel diagnostic techniques, such as WES, offer the possibility to decipher the cause of CMT subtypes, ending the diagnostic Odyssey of the patients and sparing them from unnecessary and potentially harmful treatments.

Associations between sleep duration and cognitive impairment in mild cognitive impairment

The prevalence of mild cognitive impairment (MCI) increases among elderly people and is associated with a high risk of dementia. Identifying factors that may contribute to the progress of MCI to dementia is critical. The objective of this study was to examine the association of objective sleep with cognitive performance in MCI patients. A subsample of 271 participants with a diagnosis of probable Alzheimer's disease (AD; N = 50) or mild cognitive impairment (MCI; N = 121) and 100 persons who were not cognitively impaired (NI) were recruited from a large population-based cohort in the island of Crete, Greece (3140 older adults aged >60 years). All participants underwent extensive neuropsychiatric/neuropsychological evaluation and a 3-day 24-hr actigraphy. Objective sleep variables and their association with neuropsychological performance were examined across the three groups, controlling for demographics, body mass index, depression, sleep apnea symptoms and psychotropic medications. Patients with AD had significantly longer 24-hr total sleep time (TST) compared to the MCI and NI groups. Long 24-hr TST was associated with reduced performance on tasks that placed significant demands on attention and processing speed in the MCI group and the AD group. Elderly patients with MCI have similar objective sleep duration to normal controls, whereas AD patients sleep longer. Long sleep duration in patients with multidomain subtypes of MCI is associated with critical non-memory cognitive domains. It appears that within the MCI group those that sleep longer have more severe cognitive impairment.

Liver Transplantation for Familial Amyloid Polyneuropathy (Val30Met): Long-Term Follow-up Prospective Study in a Nontransplant Center

BACKGROUND

Familial amyloidosis polyneuropathy (FAP) is a rare, progressive, and life-threatening disease inherited in the autosomal dominant pattern. Liver transplantation is the only proven disease-modifying treatment to date.

AIM

To study the long-term outcomes of patients transplanted for FAP under a multidisciplinary team care.

METHODS

We included adult patients who were transplanted for FAP indication and were followed up in a relevant clinic or admitted in our department.

RESULTS

Twelve patients (6 male) with a mean age of 43 years and mean follow-up post-transplant of 100 months were included. Three patients died in this period, 1 due to a disease-related cause. All patients had peripheral neuropathy (25% severe). Eighty-three percent had autonomic nervous system dysfunction; all men, except one, erectile dysfunction; and half of the patients several genitourinary manifestations. Gastrointestinal involvement was present in 75% of the patients. The severity of several complications related to FAP was found to be associated with waiting on the transplant list for more than 12 months.

CONCLUSIONS

Patients transplanted for FAP have a long survival. Prolonged stay on the transplant waiting list is associated with frequency and severity of disease complications. These patients are best managed in the context of multidisciplinary team care.

Cerebrospinal Fluid TAR DNA-Binding Protein 43 Combined with Tau Proteins as a Candidate Biomarker for Amyotrophic Lateral Sclerosis and Frontotemporal Dementia Spectrum Disorders

BACKGROUND

Amyotrophic lateral sclerosis (ALS) and frontotemporal dementia (FTD) are nowadays recognized as spectrum disorders with a molecular link, the TAR DNA-binding protein 43 (TDP-43), rendering it a surrogate biomarker for these disorders.

METHODS

We measured cerebrospinal fluid (CSF) levels of TDP-43, beta-amyloid peptide with 42 amino acids (Aβ42), total tau protein (τT), and tau protein phosphorylated at threonine 181 (τP-181) in 32 patients with ALS, 51 patients with FTD, and 17 healthy controls. Double-sandwich commercial enzyme-linked immunosorbent assays were used for measurements.

RESULTS

Both ALS and FTD patients presented with higher TDP-43 and τT levels compared to the control group. The combination of biomarkers in the form of the TDP-43 × τT / τP-181 formula achieved the best discrimination between ALS or FTD and controls, with sensitivities and specificities >0.8.

CONCLUSION

Combined analysis of TDP-43, τT, and τP-181 in CSF may be useful for the antemortem diagnosis of ALS and FTD.

Association between insomnia symptoms and cognitive impairment in the Cretan Aging Cohort

PURPOSE

Population aging, characteristic of modern Western societies, is associated with various forms of cognitive decline. Insomnia/insomnia-type symptoms have been reported as modifiable risk factors for cognitive decline. The objective of this study was to examine, in a comprehensive way (a) the prevalence and the risk factors associated with insomnia-type symptoms and (b) the association of insomnia-type symptoms with cognitive impairment in a large, homogeneous, community-dwelling population in the island of Crete, Greece.

METHODS

Our sample consisted of 3066 community-dwelling elders aged 60-100 years participating in the Cretan Aging Cohort. All participants were interviewed with a structured questionnaire assessing demographics, physical and mental health, sleep, lifestyle habits and cognitive function using the Mini Mental State Examination (MMSE). Furthermore, insomnia-type symptom prevalence was estimated in the presence of one or more sleep complaints. Linear and logistic regression analyses examined (a) the association between insomnia-type symptoms and demographics, physical/mental health and lifestyle and (b) the association between cognition and insomnia-type symptoms.

RESULTS

Prevalence of one or more insomnia-type symptoms was 64.6%. Multivariate analyses showed that female gender, widowhood, benzodiazepine use and physical ailments were significantly associated with insomnia-type symptoms. Multivariate models also showed that insomnia-type symptoms were associated with increased odds of cognitive impairment (p < 0.0001).

CONCLUSIONS

In a large population of older people in Crete, Greece, insomnia-type symptoms are very prevalent and associated with increased risk for cognitive impairment. Future studies should assess whether treatment of sleep problems improves or delays the deterioration of cognitive function in older adults.

Localization of Human Glutamate Dehydrogenases Provides Insights into Their Metabolic Role and Their Involvement in Disease Processes

Glutamate dehydrogenase (GDH) catalyzes the reversible deamination of L-glutamate to α-ketoglutarate and ammonia. In mammals, GDH contributes to important processes such as amino acid and carbohydrate metabolism, energy production, ammonia management, neurotransmitter recycling and insulin secretion. In humans, two isoforms of GDH are found, namely hGDH1 and hGDH2, with the former being ubiquitously expressed and the latter found mainly in brain, testis and kidney. These two iso-enzymes display highly divergent allosteric properties, especially concerning their basal activity, ADP activation and GTP inhibition. On the other hand, both enzymes are thought to predominantly localize in the mitochondrial matrix, even though alternative localizations have been proposed. To further study the subcellular localization of the two human iso-enzymes, we created HEK293 cell lines stably over-expressing hGDH1 and hGDH2. In these cell lines, immunofluorescence and enzymatic analyses verified the overexpression of both hGDH1 and hGDH2 iso-enzymes, whereas subcellular fractionation followed by immunoblotting showed their predominantly mitochondrial localization. Given that previous studies have only indirectly compared the subcellular localization of the two iso-enzymes, we co-expressed them tagged with different fluorescent dyes (green and red fluorescent protein for hGDH1 and hGDH2, respectively) and found them to co-localize. Despite the wealth of information related to the functional properties of hGDH1 and hGDH2 and the availability of the hGDH1 structure, there is still an ongoing debate concerning their metabolic role and their involvement in disease processes. Data on the localization of hGDHs, as the ones presented here, could contribute to better understanding of the function of these important human enzymes.

Cognitive screening tools for primary care settings: examining the 'Test Your Memory' and 'General Practitioner assessment of Cognition' tools in a rural aging population in Greece

BACKGROUND

Under conditions of high demand for primary care services in a setting of low financial resources, there is need for brief, easily administered cognitive screening tools for use in the primary care setting, especially in rural areas. However, interpretation of these cognitive tests' results requires knowledge on their susceptibility to cultural, educational and demographic patient characteristics.

OBJECTIVES

To assess the clinical validity of the 'Test Your Memory' (TYM) and 'General Practitioner assessment of Cognition' (GPCog) which was specifically designed for primary care practice, in a rural primary care setting in Greece, utilizing the 'Mini Mental State Examination' (MMSE) as a reference standard.

METHODS

The MMSE, TYM, and GPCog were administered to a random sample of 319 community dwelling Greek adults aged 60 to 89 years in 11 rural Primary Healthcare Centres of the Prefecture of Heraklion on the island of Crete, Greece. Analyses examined (a) The association of each instrument with demographic factors and MMSE and (b) optimal cut-off scores, sensitivity and specificity against MMSE-based cognitive impairment risk using ROC analyses with the MMSE 23/24 point cut-off as a reference standard.

RESULTS

We found a sensitivity of 80% and a specificity of 77% for TYM (35/36 or 38/39 cut-off, depending on education). Corresponding values were 89% and 61% for GPCog (7/8 cut-off), respectively.

CONCLUSION

The TYM and GPCog instruments appear to be suitable for routine use in the primary care setting as tools for cognitive impairment risk detection in elderly rural populations.

Self-reported fatigue as a risk index for dementia diagnosis

INTRODUCTION

Cognitive impairment and frailty are major problems of older age. This study aims to explore the association between frailty and cognitive impairment in a rural cohort of older subjects in southern Europe (Cretan Aging Cohort).

METHODS

Community-based, primary care, cross-sectional, study in the Heraklion Prefecture, Crete, Greece. Four hundred and two persons aged 60-100 years from the Cretan Aging Cohort [100 with dementia, 175 with mild cognitive impairment (MCI) and 127 cognitively non-impaired] were enrolled, mostly rural dwellers (86.2%). Frailty was assessed with the Simple "Frail" Questionnaire Screening Tool. Demographic data, BMI, Mini-Mental State Examination scores (MMSE), severity of dementia according to the Clinical Dementia Rating Scale, and depressive symptoms according to the Geriatric Depression Scale (GDS) were recorded.

RESULTS

Frailty was present in 17% of persons with dementia (73.8% of mild severity), in 6.3% of persons with MCI and in 8.7% of cognitively non-impaired persons (P < 0.05). Among the various frailty variables, fatigue and difficulty walking were significantly more frequently reported by persons with dementia. Each frailty variable and the frailty score correlated negatively with MMSE score and positively with GDS score and polypharmacy. Multivariate analysis revealed that reported fatigue improved the identification of dementia in addition to MMSE, significantly and independently of symptoms of depression (P = 0.04).

CONCLUSION

Frailty rates are significantly higher in persons with dementia. In this predominantly rural cohort of older subjects, reported fatigue could serve as a marker of physical decline and a complementary index for referral for further neuropsychological and neuropsychiatric evaluation.

Myelin content changes in probable Alzheimer's disease and mild cognitive impairment: Associations with age and severity of neuropsychiatric impairment

BACKGROUND

Existing indices of white matter integrity such as fractional anisotropy and magnetization transfer ratio may not provide optimal specificity to myelin content. In contrast, myelin water fraction (MWF) derived from the multiecho T₂ relaxation time technique may serve as a more direct measure of myelin content.

PURPOSE/HYPOTHESIS

The goal of the present study was to identify markers of regional demyelination in patients with probable Alzheimer's disease (AD) and mild cognitive impairment (MCI) in relation to age and severity of neuropsychiatric impairment.

POPULATION

The sample included patients diagnosed with probable AD (n = 25) or MCI (n = 43), and cognitively intact elderly controls (n = 33).

FIELD STRENGTH/SEQUENCE ASSESSMENT

Long T₂ , short T₂ , and MWF values were measured with a 1.5T scanner in periventricular and deep normal-appearing white matter (NAWM), serving as indices of intra/extracellular water content and myelin content. A comprehensive neuropsychological and neuropsychiatric assessment was administered to all participants.

STATISTICAL TESTS, RESULTS

AD patients displayed higher age-adjusted long and short T₂ values and reduced MWF values in left temporal/parietal and bilateral periventricular NAWM than controls and MCI patients (P < 0.004; one-way analysis of covariance [ANCOVA] tests). Short T₂ /MWF values in temporal, frontal, and periventricular NAWM of controls and/or MCI patients were significantly associated with episodic and semantic memory performance and depressive symptomatology (P < 0.004; partial correlation indices). The impact of age on memory performance was significantly (P < 0.01; mediated linear regression analyses) mediated by age-related changes in short T₂ and MWF values in these regions.

DATA CONCLUSION

Age-related demyelination is associated with memory impairment (especially in prodromal dementia states) and symptoms of depression in an anatomically specific manner.

LEVEL OF EVIDENCE

1 Technical Efficacy: Stage 3 J. Magn. Reson. Imaging 2018;47:1359-1372.

Expression of the human isoform of glutamate dehydrogenase, hGDH2, augments TCA cycle capacity and oxidative metabolism of glutamate during glucose deprivation in astrocytes

A key enzyme in brain glutamate homeostasis is glutamate dehydrogenase (GDH) which links carbohydrate and amino acid metabolism mediating glutamate degradation to CO₂ and expanding tricarboxylic acid (TCA) cycle capacity with intermediates, i.e. anaplerosis. Humans express two GDH isoforms, GDH1 and 2, whereas most other mammals express only GDH1. hGDH1 is widely expressed in human brain while hGDH2 is confined to astrocytes. The two isoforms display different enzymatic properties and the nature of these supports that hGDH2 expression in astrocytes potentially increases glutamate oxidation and supports the TCA cycle during energy-demanding processes such as high intensity glutamatergic signaling. However, little is known about how expression of hGDH2 affects the handling of glutamate and TCA cycle metabolism in astrocytes. Therefore, we cultured astrocytes from cerebral cortical tissue of hGDH2-expressing transgenic mice. We measured glutamate uptake and metabolism using [³ H]glutamate, while the effect on metabolic pathways of glutamate and glucose was evaluated by use of ¹³ C and ¹⁴ C substrates and analysis by mass spectrometry and determination of radioactively labeled metabolites including CO₂ , respectively. We conclude that hGDH2 expression increases capacity for uptake and oxidative metabolism of glutamate, particularly during increased workload and aglycemia. Additionally, hGDH2 expression increased utilization of branched-chain amino acids (BCAA) during aglycemia and caused a general decrease in oxidative glucose metabolism. We speculate, that expression of hGDH2 allows astrocytes to spare glucose and utilize BCAAs during substrate shortages. These findings support the proposed role of hGDH2 in astrocytes as an important fail-safe during situations of intense glutamatergic activity. GLIA 2017;65:474-488.

The impact of mild cognitive impairment on the self-regulation process: A comparison study of persons with mild cognitive impairment and cognitively healthy older adults

This study examined whether mild cognitive impairment affects the associations between personal expectations (i.e. optimism and self-efficacy), illness-related coping, and quality of life. In total, two groups of older adults participated: 127 persons diagnosed with mild cognitive impairment and 225 cognitively healthy older persons (cognitively non-impaired group). Several significant relationships observed in the cognitively non-impaired group did not reach significance among mild cognitive impairment patients, with the opposite trend noted for others (e.g. between palliative coping and physical health). These findings indicate that mild cognitive impairment may lead to problems in the self-regulation process and highlight the significance of the interplay between neurocognitive and psychosocial aspects of self-regulation.