Accuracy of the brief cognitive screening battery for diagnosing Alzheimer's disease defined by cerebrospinal fluid biomarkers and AT(N) classification: a case-control study / Acurácia da bateria breve de rastreio cognitivo no diagnóstico da doença de Alzheimer definida por biomarcadores no líquido cefalorraquidiano e classificação pelo sistema AT(N): estudo caso-controle

ABSTRACT Background: Validation of cognitive instruments for detection of Alzheimer's disease (AD) based on correlation with diagnostic biomarkers allows more reliable identification of the disease. Objectives: To investigate the accuracy of the Brief Cognitive Screening Battery (BCSB) in the differential diagnosis between AD, non-AD cognitive impairment (both defined by cerebrospinal fluid [CSF] biomarkers) and healthy cognition, and to correlate CSF biomarker results with cognitive performance. Methods: Overall, 117 individuals were evaluated: 45 patients with mild cognitive impairment (MCI) or mild dementia within the AD continuum defined by the AT(N) classification [A+T+/-(N)+/]; 27 non-AD patients with MCI or mild dementia [A-T+/-(N)+/-]; and 45 cognitively healthy individuals without CSF biomarker results. All participants underwent evaluation using the BCSB. Results: The total BCSB and delayed recall (DR) scores of the BCSB memory test showed high diagnostic accuracy, as indicated by areas under the ROC curve (AUC): 0.89 and 0.87, respectively, for discrimination between AD and non-AD versus cognitively healthy controls. Similarly, total BCSB and DR displayed high accuracy (AUC-ROC curves of 0.89 and 0.91, respectively) for differentiation between AD and controls. BCSB tests displayed low accuracy for differentiation between AD and non-AD. The CSF levels of biomarkers correlated significantly, though weakly, with DR. Conclusions: Total BCSB and DR scores presented good accuracy for differentiation between patients with a biological AD diagnosis and cognitively healthy individuals, but low accuracy for differentiating AD from non-AD patients.

RESUMO Antecedentes: A validação de testes cognitivos para identificação da doença de Alzheimer (DA) definida por biomarcadores aumenta a confiabilidade diagnóstica. Objetivos: Investigar a acurácia da Bateria Breve de Rastreio Cognitivo (BBRC) no diagnóstico diferencial entre DA, comprometimento cognitivo não-DA (ambos diagnósticos definidos por biomarcadores no líquido cefalorraquidiano-LCR) e indivíduos cognitivamente saudáveis, e investigar correlações entre desempenho nos testes e concentrações dos biomarcadores no LCR. Métodos: No total, 117 indivíduos foram avaliados. Quarenta e cinco pacientes com comprometimento cognitivo leve (CCL) ou demência leve com diagnóstico do continuum de DA definido pela classificação AT(N) [A+T+/-(N)+/-], 27 pacientes com CCL ou demência leve não-DA [A-T+/-(N)+/-], e 45 controles cognitivamente saudáveis sem estudo de biomarcadores no LCR. Os participantes foram submetidos à BBRC. Resultados: O escore total da BBRC e a evocação tardia (ET) no teste de memória da BBRC apresentaram elevada acurácia diagnóstica na diferenciação entre DA e não-DA versus controles, indicada pelas áreas sob a curva ROC (AUC) de 0,89 e 0,87, respectivamente. De modo semelhante, o escore total da BBRC e a ET mostraram elevadas acurácias (AUC-ROC de 0,89 e 0,91, respectivamente) para o diagnóstico diferencial entre DA e controles. A acurácia da BBRC foi baixa na diferenciação entre DA e não-DA. Os níveis dos biomarcadores no LCR se correlacionaram de forma significativa, embora fraca, com ET. Conclusões: Os escores totais da BCSB e a ET apresentaram boa acurácia na diferenciação entre pacientes com diagnóstico biológico de DA e controles cognitivamente saudáveis, mas baixa acurácia para diferenciar DA de não-DA.

Genetic Prion Disease: Insight from the Features and Experience of China National Surveillance for Creutzfeldt-Jakob Disease / 神经科学通报·英文版

Human genetic prion diseases (gPrDs) are directly associated with mutations and insertions in the PRNP (Prion Protein) gene. We collected and analyzed the data of 218 Chinese gPrD patients identified between Jan 2006 and June 2020. Nineteen different subtypes were identified and gPrDs accounted for 10.9% of all diagnosed PrDs within the same period. Some subtypes of gPrDs showed a degree of geographic association. The age at onset of Chinese gPrDs peaked in the 50-59 year group. Gerstmann-Sträussler-Scheinker syndrome (GSS) and fatal familial insomnia (FFI) cases usually displayed clinical symptoms earlier than genetic Creutzfeldt-Jakob disease (gCJD) patients with point mutations. A family history was more frequently recalled in P105L GSS and D178N FFI patients than T188K and E200K patients. None of the E196A gCJD patients reported a family history. The gCJD cases with point mutations always developed clinical manifestations typical of sporadic CJD (sCJD). EEG examination was not sensitive for gPrDs. sCJD-associated abnormalities on MRI were found in high proportions of GSS and gCJD patients. CSF 14-3-3 positivity was frequently detected in gCJD patients. Increased CSF tau was found in more than half of FFI and T188K gCJD cases, and an even higher proportion of E196A and E200K gCJD patients. 63.6% of P105L GSS cases showed a positive reaction in cerebrospinal fluid RT-QuIC. GSS and FFI cases had longer durations than most subtypes of gCJD. This is one of the largest studies of gPrDs in East Asians, and the illness profile of Chinese gPrDs is clearly distinct. Extremely high proportions of T188K and E196A occur among Chinese gPrDs; these mutations are rarely reported in Caucasians and Japanese.

Correlation between CSF biomarkers of Alzheimer's disease and global cognition in a psychogeriatric clinic cohort

Objective: The relationship between biomarkers of amyloid-beta aggregation (Aβ1-42) and/or neurodegeneration (Tau protein) in cerebrospinal fluid (CSF) and cognitive decline is still unclear. We aimed to ascertain whether CSF biomarkers correlate with cognitive performance in healthy and cognitively impaired subjects, starting from clinical diagnoses. Methods: We tested for correlation between CSF biomarkers and Mini-Mental State Examination (MMSE) scores in 208 subjects: 54 healthy controls, 82 with mild cognitive impairment (MCI), 46 with Alzheimer's disease (AD), and 26 with other dementias (OD). Results: MMSE correlated weakly with all CSF biomarkers in the overall sample (r = 0.242, p < 0.0006). Aβ1-42 and MMSE correlated weakly in MCI (r = 0.247, p = 0.030), and moderately in OD (r = 0.440, p = 0.027). t-Tau showed a weak inverse correlation with MMSE in controls (r = -0.284, p = 0.043) and MCI (r = -0.241, p = 0.036), and a moderate/strong correlation in OD (r = 0.665), p = 0.0003). p-Tau correlated weakly with MMSE in AD (r = -0.343, p = 0.026) and moderately in OD (r = -0.540, p = 0.0005). The Aβ1-42/p-Tau ratio had a moderate/strong correlation with MMSE in OD (r = 0.597, p = 0.001). Conclusion: CSF biomarkers correlated best with cognitive performance in OD. t-Tau correlated weakly with cognition in controls and patients with MCI. In AD, only p-Tau levels correlated with cognitive performance. This pattern, which has been reported previously, seems to indicate that CSF biomarkers might not be reliable as indicators of disease severity.

Biological markers of Alzheimers disease / Biomarcadores da doenca de Alzheimer

The challenges for establishing an early diagnosis of Alzheimer’s disease (AD) have created a need for biomarkers that reflect the core pathology of the disease. The cerebrospinal fluid (CSF) levels of total Tau (T-tau), phosphorylated Tau (P-Tau) and beta-amyloid peptide (Aβ42) reflect, respectively, neurofibrillary tangle and amyloid pathologies and are considered as surrogate markers of AD pathophysiology. The combination of low Aβ42 and high levels of T-tau and P-Tau can accurately identify patients with AD at early stages, even before the development of dementia. The combined analysis of the CSF biomarkers is also helpful for the differential diagnosis between AD and other degenerative dementias. The development of these CSF biomarkers has evolved to a novel diagnostic definition of the disease. The identification of a specific clinical phenotype combined with the in vivo evidence of pathophysiological markers offers the possibility to make a diagnosis of AD before the dementia stage with high specificity.

O desafio de se estabelecer o diagnóstico precoce de doença de Alzheimer (DA) levou ao desenvolvimento de biomarcadores que reflitam os aspectos patológicos centrais da doença. As dosagens no líquor da proteína Tau total (T-Tau), Tau fosforilada (P-Tau) e peptídeo beta-amiloide (Aβ42) no líquido cefalorraquidiano (LCR) refletem, respectivamente, as patologias Tau e amiloide, sendo consideradas como marcadores da fisiopatologia da DA. Os biomarcadores do LCR podem identificar acuradamente pacientes com DA em estágios precoces da doença, mesmo antes do desenvolvimento da demência. A análise combinada dos biomarcadores permite também fazer o diagnóstico diferencial entre DA e outras demências degenerativas. O desenvolvimento dos biomarcadores de DA conduziu a uma nova definição diagnóstica da doença. A identificação de um fenótipo clínico específico associado a uma evidência fisiopatológica in vivo provida por um biomarcador possibilita estabelecer, com alta especificidade, o diagnóstico de DA antes do estágio demencial.

Chemokines in CSF of Alzheimer's disease patients / Quimiocinas no LCR de pacientes portadores da doença de Alzheimer

Some studies have linked the presence of chemokines to the early stages of Alzheimer's disease (AD). Then, the identification of these mediators may contribute to diagnosis. Our objective was to evaluate the levels of beta-amyloid (BA), tau, phospho-tau (p-tau) and chemokines (CCL2, CXCL8 and CXCL10) in the cerebrospinal fluid (CSF) of patients with AD and healthy controls. The correlation of these markers with clinical parameters was also evaluated. The levels of p-tau were higher in AD compared to controls, while the tau/p-tau ratio was decreased. The expression of CCL2 was increased in AD. A positive correlation was observed between BA levels and all chemokines studied, and between CCL2 and p-tau levels. Our results suggest that levels of CCL2 in CSF are involved in the pathogenesis of AD and it may be an additional useful biomarker for monitoring disease progression.

Alguns estudos têm relacionado a presença de quimiocinas com estágios iniciais da doença de Alzheimer (ALZ). A identificação desses mediadores pode contribuir para um diagnóstico precoce. O objetivo deste estudo foi avaliar os níveis de beta-amiloide (BA), tau, fosfo-tau (p-tau) e quimiocinas (CCL2, CXCL8 e CXCL10) no líquido cefalorraquidiano dos pacientes com ALZ e controles saudáveis e a correlação destes marcadores com parâmetros clínicos. Os níveis de p-tau foram maiores nos pacientes com ALZ em relação aos controles, enquanto a razão tau/p-tau foi menor. Houve um aumento significativo de CCL2. Uma correlação positiva foi encontrada entre os níveis de BA e todas as quimiocinas estudadas e também entre os níveis de CCL2 e p-tau. Nossos resultados sugerem que a presença de CCL2 está envolvida na patogênese da ALZ e que esta quimiocina pode ser um marcador adicional para monitorar a progressão da doença.

Clinical and biological predictors of Alzheimer's disease in patients with amnestic mild cognitive impairment / Preditores clínicos e biológicos da evolução para doença de Alzheimer em pacientes com comprometimento cognitivo leve amnéstico

OBJECTIVE: To identify predictors of the progression from pre-dementia stages of cognitive impairment in Alzheimer's disease is relevant to clinical management and to substantiate the decision of prescribing antidementia drugs. METHOD: Longitudinal study of a cohort of elderly adults with amnestic mild cognitive impairment and healthy controls, carried out to estimate the risk and characterize predictors of the progression to Alzheimer's disease. RESULTS: Patients with amnestic mild cognitive impairment had a higher risk to develop Alzheimer's disease during follow-up (odds ratio = 4.5, CI95 percent [1.3-13.6], p = 0.010). At baseline, older age, lower scores on memory tests and presence of the APOE*4 allele predicted the progression from amnestic mild cognitive impairment to Alzheimer's disease. In a sub sample of amnestic mild cognitive impairment patients, those who progressed to Alzheimer's disease had lower cerebrospinal fluid concentrations of amyloid-beta peptide (Aβ42, p = 0.020) and higher concentrations of total TAU (p = 0.030) and phosphorylated TAU (p = 0.010), as compared to non-converters. DISCUSSION: This is the first Brazilian study to report cerebrospinal fluid biomarkers in the prediction of the conversion from MCI to Alzheimer's disease. Our data are in accordance with those reported in other settings. The measurement of cerebrospinal fluid total-TAU, phospho-TAU and Aβ42 may help identify patients with mild cognitive impairment at higher risk for developing Alzheimer's disease.

OBJETIVO: A identificação de preditores da conversão para a doença de Alzheimer em pacientes com comprometimento cognitivo leve é relevante para o manejo clínico e para decidir sobre a prescrição de drogas antidemência. MÉTODO: Estudo longitudinal em coorte de indivíduos idosos com comprometimento cognitivo leve amnéstico e controles saudáveis; estimativa do risco da progressão para doença de Alzheimer nos dois grupos; determinação das variáveis preditivas desse desfecho. RESULTADOS: Pacientes com comprometimento cognitivo leve amnéstico apresentaram maior risco de desenvolver doença de Alzheimer ao longo do seguimento (odds ratio = 4,5, CI95 por cento [1,3-13,6], p = 0,012). Na avaliação inicial, idade mais avançada, escores mais baixos nos testes cognitivos e do alelo APOE*4 foram preditores da conversão do comprometimento cognitivo leve amnéstico para doença de Alzheimer. Em uma subamostra de pacientes com comprometimento cognitivo leve amnéstico, aqueles que progrediram para doença de Alzheimer tinham concentrações liquóricas mais baixas do peptídeo beta-amilóide (Aβ42, p = 0,020) e mais altas da proteína TAU total (p = 0,030) e TAU fosforilada (p = 0,010) do que os pacientes que não progrediram para doença de Alzheimer. DISCUSSÃO: Este é o primeiro estudo brasileiro com biomarcadores liquóricos a relatar preditores da conversão comprometimento cognitivo leve-doença de Alzheimer. Nossos dados biológicos (aumento de TAU total e fosfo-TAU; redução de Aβ42), e podem auxiliar na identificação dos pacientes com comprometimento cognitivo leve com maior risco de evolução para demência.

Microtubule proteins and their post-translational forms in the cerebrospinal fluid of patients with paraparesis associated with HTLV-I infection and in SH-SY5Y cells: An in vitro model of HTLV-I-induced disease

HTLV-I-associated myelopathy/tropical spastic paraparesis (HAM/TSP) is characterized by axonal degeneration of the corticospinal tracts. The specific requirements for transport of proteins and organelles to the distal part of the long axon are crucial in the corticospinal tracts. Microtubule dysfunction could beinvolved in this disease, configuring an axonal transport disease. We measured tubulin and its posttranslational modified forms (acetylated and tyrosinated) in CSF of patients and controls, as well as tau and its phosphorylated forms. There were no significant differences in the contents of tubulin and acetyl-tubulinbetween patients and controls; tyrosyl-tubulin was not detected. In HAM/TSP, tau levels were significantly reduced, while the ratio of pT181/total tau was higher in patients than in controls, this being completely different from what is reported in other neurodegenerative diseases. Phosphorylation at T181 was also confirmed by Mass Spectrometry analysis. Western Blotting with monospecific polyclonal antibodies against pS199, pT205, pT231, pS262, pS356, pS396, pS404 and pS422 did not show differences in phosphorylation in these residues between patients and controls. Treating human SH-SY5Y neuroblastoma cells, a well-known in vitro neurite retraction model, with culture supernatant of MT-2 cells (HTLV-I infected cell line that secretes theviral Tax protein) we observed neurite retraction and an increase in tau phosphorylation at T181. A disruptionof normal phosphorylation of tau protein in T181 could result in its dysfunction, contributing to axonal damage.

Cien años de la enfermedad de Alzheimer: La inmunoterapia ¿una esperanza? / One hundred years of Alzheimer's disease: Immunotherapy a hope?

In 1906 Alois Alzheimer, described the cerebral lesions characteristic of the disorder that received his name: senile plaques and neurofibrillary tangles. Alzheimer's disease (AD) is now, 100 years after, the most prevalent form of dementia in the world. The longer life expectancy and aging of the population renders it as a serious public health problem of the future. Urgent methods of diagnosis and treatment are required, since the definitive diagnosis of AD continues to be neuropathologic. In the last 30 years several drugs have been approved to retard the progression of the disease; however, there are still no curative or preventive treatments. Although still in experimentation, the visualization of amyloid deposition by positron emission tomography or magnetic resonance imaging will allow in vivo diagnosis of AD. In addition, experiments with the amyloid vaccine are still ongoing, and very recent data suggest that intravenous gammaglobulins may be beneficial and safe for the treatment of AD.

Hyperphosphorylated tau protein in the cerebrospinal fluid of patients with Alzheimer's disease and other dementias: preliminary findings

A doença de Alzheimer (DA) se caracteriza pelo achado anátomo-patológico de acúmulo de placas senis e emaranhados neurofibrilares associados à proteína tau no tecido cerebral. A pesquisa por marcadores biológicos antemortem está focada nas concentrações das proteínas b-amilóide e tau no líquido cefalorraqueano (LCR) objetivando um diagnóstico mais precoce e acurado da doença. Os níveis de proteína tau hiperfosforilada no sítio 181 foram determinados no LCR de 34 pacientes com DA (19 com DA senil - DAS e oito com DA pré-senil -DAPS) e sete pacientes com outras demências (OD). Os níveis de fosfotau foram significativamente mais elevados em pacientes com DA quando comparados com OD (AUC 0,812), sem relação com gravidade da demência, idade de início, duração da doença e escores do Mini-Exame do Estado Mental. Não foram observadas diferenças entre os níveis de fosfotau em pacientes com DAS e DAPS. Estes achados corroboram os dados encontrados em estudos prévios e indicam que o nível de fosfotau no LCR dos pacientes pode colaborar na diferenciação da DA com outras demências.