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Individual electromagnetic profiles for the prediction of episodic memory change in early stages of dementia
Author(s) -
Colomo Alejandra García,
Sanz David López,
Nebreda Alberto,
de Frutos Jaisalmer,
Fernández Ricardo Bruña,
Losada María Luisa Delgado,
Higes Ramón López,
Maestú Fernando
Publication year - 2020
Publication title -
alzheimer's and dementia
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 6.713
H-Index - 118
eISSN - 1552-5279
pISSN - 1552-5260
DOI - 10.1002/alz.047457
Subject(s) - fractional anisotropy , dementia , neuropsychology , cognitive decline , diffusion mri , cognition , psychology , memory clinic , magnetoencephalography , disease , magnetic resonance imaging , audiology , alzheimer's disease , medicine , neuroscience , radiology , electroencephalography
Background Recent literature defines Alzheimer’s disease (AD) as a continuum consisting of three differentiated stages, preclinical, prodromal and dementia, in which the progressive neurological deterioration gives rise to a growing cognitive decline. According to this idea, presenting subjective cognitive decline (SCD), on its own or in association with a diagnosable mild cognitive impairment (MCI), increases the risk of developing AD‐related dementia in the following years. AD is usually described as a disconnection syndrome. Studies performed with magnetoencephalography (MEG) and diffusion weighted imaging (DWI) have shown alterations in patterns of functional connectivity, power spectrum, fractional anisotropy, and mean diffusivity even in the initial stages of the disease. These patterns could constitute an early biomarker, and thus allow for an early diagnosis and, hopefully, treatment. The main purpose of this study is to determine which, if any, MEG and DWI variables allow for an early differentiation of subjects with SCD or MCI who will show a worse cognitive evolution. Method We studied 64 Spanish individuals (age 71,44 ± 4,74), fourteen of which were diagnosed with MCI. The remaining 50 participants did not exhibit any objective neuropsychological impairment, but presented subjective cognitive complaints and were thus categorised as SCD. Participants were followed longitudinally and evaluated at two points in time approximately 3 years apart. All participants underwent a neuropsychological evaluation, a MEG scan, and a magnetic resonance imaging scan. From these scans, we calculated: functional connectivity, power spectrums, fractional anisotropy, and mean diffusivity values. The resulting values were used as predictors of the cognitive change experienced in episodic memory by means of a stepwise general linear model. Result We found an optimal predictive model (R2 = 0,500; p < 0,01) consisting of variables such as the alpha power in the left inferior parietal lobe (β = 15,387) and the mean diffusivity of the left cingulate part of the cingulum bundle (β = 149,720). Conclusion This region and tract have been previously reported to play a role in episodic memory, supporting the evidence that their functional or structural affectation could be an early marker of neuronal deterioration and disease progression.