Παθογενετικοί μηχανισμοί της δυσλεξίας: μια ανασκόπηση

The authors of the present paper describe the probable pathogenetic mechanisms of specific reading disability, i.e. dyslexia. This analysis is grounded on the most widespread, yet hypothetical, cognitive deficit theories which account for the emergence and causation of dyslexia. These theories, coupled with the neurobiological underpinnings, imply that it is difficult to adopt a single approach in order to locate the causal relationships inherent to the disorder. Each one of the approaches provides critical insights to the mechanisms that underlie the development of literacy skills in normally developing children when exposed to literacy acquisition. Additionally, each theory attempts to explicate the factors that may be involved in the unexpected disruption of the learning process. The difficulty in establishing accurate phonological and orthographic representations in spite of adequate exposure to print, the transparency of mother tongue, brain architecture, and familial predisposition, all seem to contribute drastically to the deficient development of dyslexic children. Neuro-imaging studies along with molecular advances have been shedding even more light onto the backstage of dyslexic reading performance. Apparently, dyslexia could only be accounted for by an interactive approach within the framework of which the different influences from scientific trends may delineate the dyslexic phenotype.Η εργασία αυτή στόχο έχει να παρουσιάσει τους πιθανούς παθογενετικούς μηχανισμούς της ειδικής αναγνωστικής δυσκολίας, δηλαδή της δυσλεξίας. Η ανάλυση που επιχειρείται βασίζεται στις πιο διαδεδομένες, αν και υποθετικές, θεωρίες νοητικού ελλείμματος, που επεξηγούν την εμφάνιση και την αιτιότητα της δυσλεξίας. Το θεωρητικό υπόβαθρο που έχει αναπτυχθεί, σε συνδυασμό και με την ύπαρξη νευροβιολογικών θεωριών, υποδηλώνει ότι είναι δύσκολο να υιοθετηθεί μια και μόνη προσέγγιση προκειμένου να εντοπιστούν οι αιτιώδεις σχέσεις που είναι συμφυείς με αυτήν τη διαταραχή. Κάθε προσέγγιση εισφέρει κρίσιμες αντιλήψεις ως προς τους μηχανισμούς που βρίσκονται στη βάση της ανάπτυξης των αναγνωστικών δεξιοτήτων σε φυσιολογικώς αναπτυσσόμενα παιδιά, κατά την κατάκτηση της ανάγνωσης και της γραφής. Επιπλέον, κάθε θεωρία επιχειρεί να εξηγήσει τους παράγοντες που ενδεχομένως εμπλέκονται στην αναπάντεχη διατάραξη της μαθησιακής διαδικασίας. Η δυσκολία καθιέρωσης ορθών φωνολογικών και ορθογραφικών αναπαραστάσεων, παρά την ικανή έκθεση στον έντυπο λόγο, η διαφάνεια της μητρικής γλώσσας, η αρχιτεκτονική του εγκεφάλου και η οικογενειακή προδιάθεση, όλα δείχνουν ότι συμβάλλουν δραστικά στην ελλειμματική ανάπτυξη των δυσλεκτικών παιδιών. Oι νευροαπεικονιστικές μελέτες παράλληλα με την πρόοδο στη μοριακή βιολογία και γενετική φωτίζουν ακόμα περισσότερο τo παρασκήνιο της δυσλεκτικής αναγνωστικής επίδοσης. Προφανώς, μόνο μια διαδραστική προσέγγιση θα μπορούσε να εξηγήσει τη δυσλεξία, στο πλαίσιο της οποίας οι διαφορετικές επιρροές από τις επιστημονικές τάσεις ενδέχεται να διασαφηνίσουν το δυσλεκτικό φαινότυπο

A Neglected Drama for Elders: Discrepancy Between Self-Perception and Objective Performance Regarding Financial Capacity in Patients With Cognitive Deficits

The article aims at investigating whether patients from Greece with different kinds of cognitive deficits (resulting from Alzheimer’s Disease, Parkinson’s Disease Dementia, and Mild Cognitive Impairment) can be characterized as financially capable (based on neuropsychological assessment), and if this claimed (in)capacity is in accordance with their personal belief of (in)capacity. Results revealed that the vast majority of the mild, moderate and severe Alzheimer’s disease patients as well as patients with Mild Cognitive Impairment and Parkinson’s disease, who scored significantly lower than normal on a relevant financial decision-making capacity test, believed that they were capable to handle their finances. This finding is in contrast with their actual financial capacity scores and the beliefs of their family members-caregivers on this issue. Some critical questions concerning incapacity and intellectual insight are raised, and future cross-cultural investigative attempts on this issue are suggested

Diasemiotic translation of neuro-diagnostic tools into Greek

Translated neuro-diagnostic tools, which assess cognitive skills, call for authors, readers, translators, evaluators for the quality of translations, neuro-scientists and examinees as users.

Enhancement of visuospatial working memory by the differential outcomes procedure in Mild Cognitive Impairment and Alzheimer’s Disease

In the present study we investigated the efficacy of the differential outcome procedure (DOP) to improve visuospatial working memory in patients with Alzheimer’s disease and Mild Cognitive Impairment (MCI). The DOP associates correct responses to the to-be-remember stimulus with unique outcomes. Eleven patients diagnosed with Alzheimer’s disease, 11 participants with MCI, and 17 healthy matched controls performed a spatial delayed memory task under the DOP and a control condition (non-differential outcomes –NOP-). We found that performance (terminal accuracy) was significantly better in the DOP condition relative to the NOP condition in all three groups of participants. AD patients performed worse, and took longer to benefit from the DOP. In line with previous animal and human research, we propose that the DOP activates brain structures and cognitive mechanisms that are less affected by healthy and pathological aging, optimizing in this way the function of the cognitive system

Are CSF neopterin levels a marker of disease activity in multiple sclerosis?

The study aimed to evaluate neopterin levels in cerebro-spinal fluid (CSF) as a marker of disease activation and progression of multiple sclerosis (MS). Neopterin, a substance known to be released from macrophages and monocytes at increased rates in cellular immune reactions, was investigated by radioimmunoassay, in the CSF of 19 patients with MS during exacerbations of the disease, in 34 patients with other neurological diseases (OND) and in 20 normal subjects used as controls. Poser's criteria were used for the diagnosis of MS. Although elevated neopterin levels in the CSF of patients with MS during exacerbations have been reported by other investigators, we found such elevation in only 4 out of 19 patients with MS (21%), in 5 out of 34 patients with OND (14.7%), and in none of the control group. Student's t-test was used for statistical analysis. There was no significant difference in the CSF values of the MS patients, the patients with OND (p > 0.05) or the controls. These results indicate that neopterin levels in CSF may not be considered a marker of disease activity in MS

Functional disorganization of small-world brain networks in mild Alzheimer's disease and amnestic Mild cognitive impairment:An EEG study using Relative Wavelet Entropy (RWE)

Previous neuroscientific findings have linked Alzheimer's disease (AD) with less efficient information processing and brain network disorganization. However, pathological alterations of the brain networks during the preclinical phase of amnestic Mild Cognitive Impairment (aMCI) remain largely unknown. The present study aimed at comparing patterns of the detection of functional disorganization in MCI relative to Mild Dementia (MD). Participants consisted of 23 cognitively healthy adults, 17 aMCI and 24 mild AD patients who underwent electroencephalographic (EEG) data acquisition during a resting-state condition. Synchronization analysis through the Orthogonal Discrete Wavelet Transform (ODWT), and directional brain network analysis were applied on the EEG data. This computational model was performed for networks that have the same number of edges (N=500, 600, 700, 800 edges) across all participants and groups (fixed density values). All groups exhibited a small-world (SW) brain architecture. However, we found a significant reduction in the SW brain architecture in both aMCI and MD patients relative to the group of Healthy controls. This functional disorganization was also correlated with the participant's generic cognitive status. The deterioration of the network's organization was caused mainly by deficient local information processing as quantified by the mean cluster coefficient value. Functional hubs were identified through the normalized betweenness centrality metric. Analysis of the local characteristics showed relative hub preservation even with statistically significant reduced strength. Compensatory phenomena were also evident through the formation of additional hubs on left frontal and parietal regions. Our results indicate a declined functional network organization even during the prodromal phase. Degeneration is evident even in the preclinical phase and coexists with transient network reorganization due to compensation

Comparative Study and Application of the EFA-4 Diagnostic Tool to Alzheimer’s Disease and Mild Cognitive Impairment

Speech is a cortical function that includes virtual, mobile and sensory part for the understanding and the expression of spoken and written word. This study shows the Greek adaptation of the diagnostic tool «Examining for aphasia» or EFA -4. In dementia and especially in Alzheimer’s disease–AD, the speech disorders are among the main diagnostic feature, along with the impairment of memory. How, however, will we recognize Dementia and separate it from the early stage of Mild Cognitive Impairment- MCI according to speech disorders?The diagnostic tool EFA-4 is a regulatory, reliable and valid measure of the speech disorders. The test was administered to 50 normal elders, 50 patients with AD and 31 patients with MCI. The sample selection, although it had a uniform age, was regardless of origin, marital status and socioeconomic status. According to the results of the research, the EFA-4 is perceived to be particularly useful in the setting of language deficits of the patients with AD, who participated in the survey.Specifically, the cut offs showed that the average of the EFA-4 for the normal range ranged from 74,5 – 74,8. Moreover the cut offs showed that the average of EFA-4 for patients with AD ranges from 36.8-46.1 and for patients with MCI ranges from 62.2 - 66.7