BACKGROUND: Studies of elderly subjects using biomarkers that are proxies for Alzheimer's disease (AD) pathology have the potential to document meaningful relationships between cognitive performance and biomarker changes along the AD continuum. OBJECTIVE: To document cognitive performance differences across distinct AD stages using a categorization based on the presence of PET-assessed amyloid-β (Aβ) burden and neurodegeneration. METHODS: Patients with mild dementia compatible with AD (n = 38) or amnestic mild cognitive impairment (aMCI; n = 43) and a cognitively unimpaired group (n = 27) underwent PET with Pittsburgh compound-B (PiB) assessing Aβ aggregation (A+) and [18F]FDG-PET assessing neurodegeneration ((N)+). Cognitive performance was assessed with verbal and visual episodic memory tests and the Mini-Mental State Examination. RESULTS: The A+(N)+ subgroup (n = 32) showed decreased (p < 0.001) cognitive test scores compared to both A+(N)-(n = 18) and A-(N)-(n = 49) subjects, who presented highly similar mean cognitive scores. Despite its modest size (n = 9), the A-(N)+ subgroup showed lower (p < 0.043) verbal memory scores relative to A-(N)-subjects, and trend lower (p = 0.096) scores relative to A+(N)-subjects. Continuous Aβ measures (standard uptake value ratios of PiB uptake) were correlated most significantly with visual memory scores both in the overall sample and when analyses were restricted to dementia or (N)+ subjects, but not in non-dementia or (N)-groups. CONCLUSION: These results demonstrate that significant Aβ-cognition relationships are highly salient at disease stages involving neurodegeneration. The fact that findings relating Aβ burden to memory performance were detected only at (N)+ stages, together with the similarity of test scores between A+(N)-and A-(N)-subjects, reinforce the view that Aβ-cognition relationships during early AD stages may remain undetectable unless substantially large samples are evaluated.
BACKGROUND: Studies of elderly subjects using biomarkers that are proxies for Alzheimer's disease (AD) pathology have the potential to document meaningful relationships between cognitive performance and biomarker changes along the AD continuum. OBJECTIVE: To document cognitive performance differences across distinct AD stages using a categorization based on the presence of PET-assessed amyloid-β (Aβ) burden and neurodegeneration. METHODS:Patients with mild dementia compatible with AD (n = 38) or amnestic mild cognitive impairment (aMCI; n = 43) and a cognitively unimpaired group (n = 27) underwent PET with Pittsburgh compound-B (PiB) assessing Aβ aggregation (A+) and [18F]FDG-PET assessing neurodegeneration ((N)+). Cognitive performance was assessed with verbal and visual episodic memory tests and the Mini-Mental State Examination. RESULTS: The A+(N)+ subgroup (n = 32) showed decreased (p < 0.001) cognitive test scores compared to both A+(N)-(n = 18) and A-(N)-(n = 49) subjects, who presented highly similar mean cognitive scores. Despite its modest size (n = 9), the A-(N)+ subgroup showed lower (p < 0.043) verbal memory scores relative to A-(N)-subjects, and trend lower (p = 0.096) scores relative to A+(N)-subjects. Continuous Aβ measures (standard uptake value ratios of PiB uptake) were correlated most significantly with visual memory scores both in the overall sample and when analyses were restricted to dementia or (N)+ subjects, but not in non-dementia or (N)-groups. CONCLUSION: These results demonstrate that significant Aβ-cognition relationships are highly salient at disease stages involving neurodegeneration. The fact that findings relating Aβ burden to memory performance were detected only at (N)+ stages, together with the similarity of test scores between A+(N)-and A-(N)-subjects, reinforce the view that Aβ-cognition relationships during early AD stages may remain undetectable unless substantially large samples are evaluated.
Authors: Kallene Summer Moreira Vidal; Diego Decleva; Mirella Telles Salgueiro Barboni; Balàzs Vince Nagy; Paulo Augusto Hidalgo de Menezes; Avinash Aher; Artur Martins Coutinho; Paula Squarzoni; Daniele de Paula Faria; Fabio Luis de Souza Duran; Carlos Alberto Buchpiguel; Jan Kremers; Geraldo Busatto Filho; Dora Fix Ventura Journal: Invest Ophthalmol Vis Sci Date: 2022-05-02 Impact factor: 4.925
Authors: Eliane Correa Miotto; Sonia Maria Dozzi Brucki; Carlos T Cerqueira; Paulo R Bazán; Geise Aline de Almeida Silva; Maria da Graça M Martin; Paula Squarzoni da Silveira; Daniele de Paula Faria; Artur Martins Coutinho; Carlos Alberto Buchpiguel; Geraldo Busatto Filho; Ricardo Nitrini Journal: J Alzheimers Dis Date: 2022 Impact factor: 4.160