Abstract
Background: The challenge in Alzheimer’s disease (AD) research -the world most prevalent dementia-remains on finding preclinical markers that can predict progression to the disease. In this respect electrophysiological (EEG) measures seem promising, based on their sensitivity to the appearance of subtle episodic memory (EM) alterations, which become an AD risk-factor when in the presence of B-amyloid burden (AB+; AD-biomarker). Aim: We aimed to identify event-related potential (ERP) signatures of AD-linked EM alterations in elder cognitively normal subjects at-risk for AD.
Methods: EEG data was collected on EGI 256-channels, over 6 yearly sessions, in 15 controls (controls_AB-), 15 non-converters (stable_AB+), and 15 converters to prodromal AD (converters_AB+; considered before AD-diagnosis) from the INSIGHTpre-AD cohort. We analysed the typical ERP response to a classic task of verbal memory recognition of old or new words (i.e. P3 and FN400 [0.25-0.34 and 0.51-0.57ms], P600 [0.62-0.77ms], and the late positive component [monitoring; 0.87-1.04ms]). The new words (seen at-new) were related to the old words (previously encoded) either in their number of repetitions or in their semantic content.
Results: During follow-up, the converters_AB+ showed increased reaction time and decreased accuracy in word recognition. The mean amplitude of the recognition of old vs new words was greater on the left fronto-temporal and posterior parietal regions, while the contrary was observed on the right hemisphere. Significantly, the converters_AB+ showed lower mean amplitude recognizing the old words when compared with the controls_AB- and the stable_AB+ in a left occipital region during the P600 time-window, underlying the classic old-new recognition effect. Conclusion: Our findings show amplitude differences associated with AD-linked EM alterations before the diagnosis is established, representing potential ERP signatures of progression to AD in at-risk individuals, while they remain cognitively normal.
Short Bio
Filipa Raposo Pereira is a Portuguese neuroscientist who never worked or studied at any University in Portugal. She left the country when she was 18 to study Medical Engineering at Cardiff University, UK, which gave her the basis in both engineering (Physics and Mechanics) and medicine. After exploring some other working avenues, she then swaps paths to Neuroimaging and Cognitive Neuroscience by taking a Master’s in Kings college London, UK. Here she begun dwelling on the research of drugs of addiction on different cognitive domains, culminating on a thesis exploring the effects of cannabis abuse on first-episode psychosis (Schizophrenia).
She then went on to take a Ph.D. at Amsterdam University, the Netherlands, exploring the effects of GHB as a drug of addiction and GHB-induced coma on the brain. This research deeply contributed to her knowledge in cognitive domains such as memory and affection, as well as in a vast domain of neuroimaging techniques and neuroanatomy. Recently she has changed paths within the Neuroscience domain, and she is currently a post-doc at the Paris Brain Institute (ICM), Sorbonne University, France, researching potential neuropsychological and EEG markers that can predict at an asymptomatic at-risk stage, who will develop Alzheimer's disease in the future. Part of the work she will present today.