Early Detection of Learning Difficulties when Confronted with Novel Information in Preclinical Alzheimer’s Disease Stage 1

A1 Journal article (refereed)


Internal Authors/Editors


Publication Details

List of Authors: Adrià Tort-Merino, Natalia Valech, Claudia Peñaloza, Petra Grönholm-Nyman, María León, Jaume Olives, Ainara Estanga, Mirian Ecay-Torres, Juan Fortea, Pablo Martínez-Lage, José L. Molinuevo, Matti Laine, Antoni Rodríguez-Fornells, Lorena Rami
Publisher: IOS Press
Publication year: 2017
Journal: Journal of Alzheimer's Disease
Volume number: 58
Issue number: 3
Start page: 855
End page: 870


Abstract

We employed a highly demanding experimental associative learning
test (the AFE-T) to explore memory functioning in Preclinical
Alzheimer’s Disease stage 1 (PreAD-1) and stage 2 (PreAD-2). The task
consisted in the learning of unknown object/name pairs and our
comprehensive setup allowed the analysis
of learning curves, immediate recall, long-term forgetting rates at one
week, three months, and six months, and relearning curves. Forty-nine
cognitively healthy subjects were included and classified according to
the presence or absence of abnormal CSF biomarkers (Control, n = 31;
PreAD-1, n = 14; PreAD-2, n = 4). Control and PreAD-1 performances on
the experimental test were compared by controlling for age and
education. These analyses showed clear learning difficulties in PreAD-1
subjects (F = 6.98; p = 0.01). Between-group differences in long-term
forgetting rates were less notable, reaching statistical significance
only for the three-month cued forgetting rate (F = 4.83; p = 0.03).
Similarly, relearning sessions showed only statistical trends between
the groups (F = 3.22; p = 0.08). In the whole sample, significant
correlations between CSF Aβ42/tau ratio and the AFE-T were found, both
in the total learning score (r = 0.52; p < 0.001) and in the
three-month cued forgetting rate (r = –0.38; p < 0.01). Descriptive
subanalyses involving PreAD-2 suggested greater learning and recall
difficulties in these subjects when compared with the PreAD-1 group. The
present results suggest that explicit learning difficulties when
binding information could be one of the earliest signs of the future
emergence of episodic memory difficulties on the Alzheimer’s disease
continuum. Our findings indicate that the AFE-T is a sensitive test,
capable of detecting subtle memory difficulties in PreAD-1.

Last updated on 2019-17-06 at 05:01