Background: Diagnosis of prodromal Alzheimer's disease (AD) still represents a hot topic and
there is a growing interest for the detection of early and non-invasive biomarkers. Although progressive
episodic memory impairment is the typical predominant feature of AD, communicative difficulties can be
already present at the early stages of the disease.
Objective: This study investigated the narrative discourse production deficit as a hallmark of CSFdefined
prodromal AD and its correlation with cerebral hypoperfusion pattern.
Method: Narrative assessment with a multilevel procedure for discourse analysis was conducted on 28
subjects with Mild Cognitive impairment (15 MCI due to AD; 13 MCI non-AD) and 28 healthy controls.
The diagnostic workup included CSF AD biomarkers. Cerebral hypoperfusion pattern was identified by
SPECT image processing.
Results: The results showed that the discourse analysis of global coherence and lexical informativeness
indexes allowed to identify MCI due to AD from MCI non-AD and healthy subjects. These findings allow
to hypothesize that the loss of narrative efficacy could be a possible early clinical hallmark of the
Alzheimer’s disease. Furthermore, a significant correlation of global coherence and lexical informativeness
reduction with the SPECT hypoperfusion was found in the dorsal aspect of the anterior part of the
left inferior frontal gyrus, supporting the hypothesis that this area has a significant role in communicative
efficacy, and in particular, in semantic selection executive control.
Conclusion: This study therefore contributes to the understanding of neural networks for language processing
and their involvement in prodromal Alzheimer's disease. It also suggests an easy and sensitive tool
for clinical practice that can help identifying individuals with prodromal Alzheimer’s disease.
