LITERATURE UPDATE
also assessed, albeit in a small number of eligible studies, for AD vs. CU (mean effect size, 95% CI 1.89 [1.86–1.92]) and for MCI vs. CU groups (mean effect size, 95% CI 4.16 [3.61–4.71]).
Recent diagnostic techniques for the detection of Alzheimer’s disease: a short review
Bhujbal SS, Kad MM, Patole VC. Ir J Med Sci. 2023 Oct; 192 (5): 2417–26. doi: 10.1007/s11845-022-03244-y.
Hippocampal neurons showing tau protein aggregating in neurofibrillary tangles (immunohistochemistry [IHC] staining).
diagnosis methods and identification of novel biomarkers are necessary for managing Alzheimer’s disease (AD) and facilitating effective prognosis and treatment. AD has a multifactorial nature and involves complex molecular mechanism, which causes neuronal degeneration.
The primary challenges in early AD detection include patient heterogeneity and lack of precise diagnosis at the preclinical stage. Several cerebrospinal fluid (CSF) and blood biomarkers have been proposed to show excellent diagnosis ability by identifying tau pathology and cerebral amyloid beta (Aβ) for AD. Intense research endeavours are being made to develop ultrasensitive detection techniques and find potent biomarkers for early AD diagnosis. To mitigate AD worldwide, understanding various CSF biomarkers, blood biomarkers, and techniques that can be used for early diagnosis is imperative. This review attempts to
provide information regarding AD pathophysiology, genetic and non- genetic factors associated with AD, several potential blood and CSF biomarkers, such as neurofilament light, neurogranin, Aβ and tau, along with biomarkers under development for AD detection. In addition, numerous techniques, such as neuroimaging, spectroscopic techniques, biosensors and neuroproteomics, which are being explored to aid early AD detection, have been discussed. The insights thus gained would help in finding potential biomarkers and suitable techniques for the accurate diagnosis of early AD before cognitive dysfunction.
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Utility of Blood-Based Tau Biomarkers for Mild Cognitive Impairment and Alzheimer’s Disease: Systematic Review and Meta-Analysis
Zabala-Findlay A, Penny LK, Lofthouse RA et al. Cells. 2023 Apr 18; 12 (8): 1184. doi: 10.3390/cells12081184.
With the development of new technologies capable of detecting low concentrations of Alzheimer’s disease (AD)-relevant biomarkers, the idea of a blood-based diagnosis of AD is nearing reality. This study aims to consider the evidence of total and phosphorylated tau as blood-based biomarkers for mild cognitive impairment (MCI) and AD when compared to healthy controls. Studies published between 1 January 2012 and 1 May 2021 (Embase and MEDLINE databases) measuring plasma/ serum levels of tau in AD, MCI, and control cohorts were screened for eligibility, including quality and bias assessment via a modified QUADAS. The meta-analyses comprised 48 studies assessing total tau (t-tau), tau phosphorylated at threonine 181 (p-tau181), and tau phosphorylated at threonine 217 (p-tau217), comparing the ratio of biomarker concentrations in MCI, AD, and cognitively unimpaired (CU) controls.
Plasma/serum p-tau181 (mean effect size, 95% confidence interval [CI] 2.02 [1.76–2.27]) and t-tau (mean effect size, 95% CI 1.77 [1.49–2.04]) were elevated in AD study participants compared to controls. Plasma/serum p-tau181 (mean effect size, 95% CI 1.34 [1.20–1.49]) and t-tau (mean effect size, 95% CI 1.47 [1.26– 1.67]) were also elevated with moderate effect size in MCI study participants compared to controls. p-tau217 was
Alzheimer’s disease (AD) is a neurological condition that affects millions of individuals around the world and for which there are few effective therapies. Dementia is characterised by the formation of senile plaques and neurofibrillary tangles, which is followed by neurotoxicity that results in memory loss and mortality.
Pathogenesis occurs several years
before the onset of disease. As the disease-modifying drugs are most effective in the early stages of Alzheimer’s disease, biomarkers for early detection of disease and their development are crucial. This review discusses the diagnostic
utility, benefits and limitations of traditional techniques such as neuroimaging, cognitive testing, positron emission tomography, and biomarkers, as well as the novel techniques such as artificial intelligence, machine learning, immunotherapy, and blood test approaches for early detection, understanding and treatment of AD.
A 19-Year-Old Adolescent with Probable Alzheimer’s Disease Jia J, Zhang Y, Shi Y et al. J Alzheimers Dis. 2023; 91 (3): 915–922. doi: 10.3233/ JAD-221065.
Alzheimer’s disease (AD) primarily affects older adults. In this report, the authors present the case of a 19-year-old male with gradual memory decline for two years and World Health Organization-University of California Los Angeles Auditory Verbal Learning Test (WHO-UCLA AVLT) results also showing memory impairment. Positron emission tomography- magnetic resonance imaging with 18F fluorodeoxyglucose revealed atrophy of the bilateral hippocampus and hypometabolism in the bilateral temporal lobe. Examination of the patient’s cerebrospinal fluid showed an increased concentration of p-tau181 and a decreased amyloid-β 42/40 ratio. However, through whole-genome sequencing, no known gene mutations were identified.
Considering the above, the patient was diagnosed with probable AD.
APRIL 2024
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