The network structure of cognitive impairment: from Subjective Cognitive Decline to Alzheimer's Disease.

It was proposed that a reorganization of the relationships between cognitive functions occurs in dementia, a vision that surpasses the idea of a mere decline of specific domains. The complexity of cognitive structure, as assessed by neuropsychological tests, can be captured by Exploratory Graph Analysis (EGA).EGA was applied to the neuropsychological assessment of people (humans) with Subjective Cognitive Decline (SCD), Mild Cognitive Impairment (MCI), and Alzheimer's Disease (AD) (Total N=638). Both sexes were included.In AD, memory scores detach from the other cognitive functions and memory subdomains reduce their reciprocal relation. SCD showed a pattern of segregated neuropsychological domains, and MCI showed a noisy and less stable pattern.Results suggest that AD drives a reorganization of cognitive functions toward a less fractionated architecture compared to preclinical conditions. Cognitive functions show a reorganization that goes beyond the performance decline. Results also have clinical implications in test interpretations and usage.Significance Statement The manuscript proposes an innovative vision for the study of the complex reorganization of cognition in people with dementia.We applied a sophisticated, reliable, cutting-edge statistical method (i.e., Exploratory Graph Analysis - EGA) to the neuropsychological evaluations of 638 patients classified into Subjective Cognitive Decline (N=155), Mild Cognitive Impairment (N=242) and Alzheimer's Disease (N=241).Patients with Alzheimer's Disease showed a simplified architecture as compared to subjects with Subjective Cognitive Decline. The MCI group resulted in sharing specific aspects with the SCD and others with the AD.Recognizing the complexity of the cognitive organization is fundamental for properly understanding cognitive impairment and stimulate the discussion about the interpretation of neuropsychological profiles from a more systemic point of view.

Genuine Memory Deficits as Assessed by the Free and Cued Selective Reminding Test (FCSRT) in the Behavioural Variant of Frontotemporal Dementia. A Systematic Review and Meta-analysis Study.

The current diagnostic criteria for the behavioural variant of frontotemporal dementia (bvFTD) foresee a relative sparing of long-term memory. Although bvFTD patients were thought to report secondary memory deficits associated with prefrontal dysfunctions, some studies indicated the presence of a "genuine memory deficit" related to mesial temporal lobe dysfunctions. Among various neuropsychological tests, the Free and Cue Selective Reminding Test (FCSRT) has been recommended to distinguish genuine from apparent amnesia. We conducted a systematic review and a random effect Bayesian meta-analysis to evaluate the nature and severity of memory deficit in bvFTD. Our objective was to determine whether the existing literature offers evidence of genuine or apparent amnesia in patients with bvFTD, as assessed via the FCSRT. On 06/19/2021, we conducted a search across four databases (PMC, Scopus, Web of Science, and PubMed). We included all studies that evaluated memory performance using the FCSRT in patients with bvFTD, as long as they also included either cognitively unimpaired participants or AD groups. We tested publication bias through the Funnel plot and Egger's test. To assess the quality of studies, we used the Newcastle-Ottawa quality assessment scale adapted for cross-sectional studies. We included 16 studies in the meta-analysis. The results showed that bvFTD patients perform better than AD patients (pooled effects between 0.95 and 1.14), as their memory performance stands between AD and control groups (pooled effects between - 2.19 and - 1.25). Moreover, patients with bvFTD present both genuine and secondary memory disorders. As a major limitation of this study, due to our adoption of a rigorous methodology and stringent inclusion criteria, we ended up with just 16 studies. Nonetheless, our robust findings can contribute to the ongoing discussion on international consensus criteria for bvFTD and the selection of appropriate neuropsychological tools to facilitate the differential diagnosis between AD and bvFTD.

Visuo-Spatial Working Memory and Mathematical Skills in Children: A Network Analysis Study.

Visuo-spatial working memory is one of the main domain-general cognitive mechanisms underlying mathematical abilities and their development in children. However, if visuo-spatial working memory involves different processes and components, then the term 'mathematics' refers to a broad concept that includes multiple domains and skills. The aim of this present study was to investigate the relationship between different visuo-spatial working memory components and several mathematical abilities in a sample of third- to fifth-grade Italian children. To assess the relationships between different visuo-spatial working memory components and different mathematical abilities, we relied on Network Analysis (NA). Results indicate that some but not all visuo-spatial working memory components are associated with some mathematical abilities.

The indirect effect of cognitive reserve on the relationship between age and cognition in pathological ageing: A cross-sectional retrospective study in an unselected and consecutively enrolled sample.

Cognitive reserve (CR) allows individuals to maintain cognitive functionality even in the presence of pathologies. The compensation hypothesis suggests that CR plays an indirect role between age and cognitive decline, contrasting the negative effect of ageing on cognition. We test this hypothesis in an unselected and consecutively enrolled sample of memory clinic attendees (n = 134) who completed the CR Index questionnaire and three neuropsychological tests assessing global cognition (MMSE, FAB, CDT). Participants were divided into two groups based on standard diagnostic criteria (DSM-5): those who were cognitively impaired (n = 92) and those who were preserved (n = 42). A principal component analysis was used to extract a composite measure of global cognitive functioning from the three neuropsychological tests, and mediation analysis was used to examine the relationship between CR, age and global cognitive functioning in the two groups. Results revealed that: (i) age had a significant direct negative effect on the global cognitive score in both groups; (ii) the three socio-behavioural proxies of CR together suppress the direct negative relationship between age and global cognitive score in cognitively impaired patients but not in cognitively preserved participants. This study confirms the association between CR, age and cognition and allows us to validate its role in a population with cognitive impairment and extend findings to a low-to-middle educated population. These results hold important implications for public health and wellness promotion, emphasising the beneficial role of maintaining healthy and active physical, cognitive and social lifestyles.

Spelling acquisition in a consistent orthography: The facilitatory effect of syllable frequency in novice spellers.

This study investigates the effects of two sublexical variables, syllable frequency, and word length, in the spelling acquisition of novice spellers dealing with a transparent orthography, such as Italian. Two groups of 1 st-grade Italian children were tested respectively after 4 and 8 months of schooling, with a spelling-to-dictation task of single words created ad hoc by manipulating syllable frequency orthogonally (high vs low frequency of the first syllable) and length (short vs long words). The results show that after only four months of schooling, children could offset their difficulty in writing long words by taking advantage of the high frequency of the initial syllable. However, the regularity of Italian spelling makes it easy to capture fine-sized phoneme-to-grapheme units, rendering the syllable effect no longer detectable in more schooled children.

Spelling deficits in children with intellectual disabilities: Evidence from a regular orthography.

Introduction: In individuals with intellectual disabilities (ID), efficient reading and writing skills promote social integration, self-autonomy, and independence. However, research has mainly focused on reading skills, while evidence on spelling skills is scarce and mostly on English-speaking subjects. In the present research project, we compared the spelling skills of children with intellectual disabilities (ID) learning in Italian, a regular orthography, to those of typically developing children matched for school level. Methods: In the first study, the performance on a Passage Dictation Test of forty-four children with ID attending regular classrooms from 4th to 8th grades (mean age = 12.16 years; SD = 1.57) were compared with controls matched for sex and grade. In the second study, a Words and Nonwords Dictation Test was administered (with stimuli varying for lexicality, orthographic complexity, regularity of transcription, and the presence of different types of phonetic-phonological difficulties) to twenty-two children with ID attending regular classrooms from 4th to 8th grades (mean age = 12.2 years; SD = 1.37) and 22 controls matched for sex and grade. In both studies, an error analysis was performed to characterize types of misspellings. Separate ANOVAs were performed on z scores. Results: Children with ID generally had a lower performance than controls. In the Passage Dictation Test, they showed a higher number of phonological (and phonetic-phonological) errors than phonologically plausible ones, indicating, as a group, predominant phonological difficulties as compared to lexical-orthographic ones. In the Words and Nonwords Dictation Test, they performed poorly on regular stimuli presenting specific types of phonetic-to-phonological difficulties (geminates, non-continuant consonants) and committed more minimal distance, context-sensitive and simple conversion misspellings. However, deficits in the orthographic-lexical procedure, as indicated by a low performance in words with unpredictable spelling, were present in a high percentage of children. Discussion: It is concluded that children with ID have significant spelling difficulties not confined to the orthographic process but also in phoneme-to-grapheme mapping that, in a regular orthography like Italian, should be acquired early and easily.

Sensitivity to distributional properties of the orthography in the spelling of Italian children with dyslexia.

The study examines statistical learning in the spelling of Italian children with dyslexia and typically developing readers by studying their sensitivity to probabilistic cues in phoneme-grapheme mappings. In the first experiment children spelled to dictation regular words and words with unpredictable spelling that contained either a high- or a low-frequency (i.e., typical or atypical) sound-spelling mappings. Children with dyslexia were found to rely on probabilistic cues in writing stimuli with unpredictable spelling to a greater extent than typically developing children. The difficulties of children with dyslexia on words with unpredictable spelling were limited to those containing atypical mappings. In the second experiment children spelled new stimuli, that is, pseudowords, containing phonological segments with unpredictable mappings. The interaction between lexical knowledge and reliance on probabilistic cues was examined through a lexical priming paradigm in which pseudowords were primed by words containing related typical or atypical sound-to-spelling mappings. In spelling pseudowords, children with dyslexia showed sensitivity to probabilistic cues in the phoneme-to-grapheme mapping but lexical priming effects were also found, although to a smaller extent than in typically developing readers. The results suggest that children with dyslexia have a limited orthographic lexicon but are able to extract regularities from the orthographic system and rely on probabilistic cues in spelling words and pseudowords.

Learning to spell in a language with transparent orthography: Distributional properties of orthography and whole-word lexical processing.

We examined how whole-word lexical information and knowledge of distributional properties of orthography interact in children's spelling. High- versus low-frequency words, which included inconsistently spelled segments occurring more or less frequently in the orthography, were used in two experiments: (a) word spelling; (b) lexical priming of pseudoword spelling. Participants were 1st-, 2nd-, and 4th-grade Italian children. Word spelling showed sensitivity to the distributional properties of orthography in all children: accuracy in spelling uncommon transcription segments emerged progressively as a function of word frequency and schooling. Lexical priming effects emerged as a function of age. When related primes contained an uncommon segment, 2nd- and 4th-graders preferred uncommon segments than common ones in spelling target pseudowords, thus inverting the response trend found in the control condition. A smaller but significant effect was present in 1st- graders, who, unlike 2nd- and 4th-graders, still preferred common segments, only slightly increasing the use of uncommon ones. A larger priming effect emerged for high-frequency primes than low-frequency ones. Results indicate that children learning to spell in a transparent orthography are sensitive to the distributional properties of the orthography. However, whole-word lexical representations are also used, with larger effects in more skilled pupils.

Independent adaptation mechanisms for numerosity and size perception provide evidence against a common sense of magnitude.

How numerical quantity is processed is a central issue for cognition. On the one hand the "number sense theory" claims that numerosity is perceived directly, and may represent an early precursor for acquisition of mathematical skills. On the other, the "theory of magnitude" notes that numerosity correlates with many continuous properties such as size and density, and may therefore not exist as an independent feature, but be part of a more general system of magnitude. In this study we examined interactions in sensitivity between numerosity and size perception. In a group of children, we measured psychophysically two sensory parameters: perceptual adaptation and discrimination thresholds for both size and numerosity. Neither discrimination thresholds nor adaptation strength for numerosity and size correlated across participants. This clear lack of correlation (confirmed by Bayesian analyses) suggests that numerosity and size interference effects are unlikely to reflect a shared sensory representation. We suggest these small interference effects may rather result from top-down phenomena occurring at late decisional levels rather than a primary "sense of magnitude".

Spelling Impairments in Italian Dyslexic Children with and without a History of Early Language Delay. Are There Any Differences?

Language delay is considered a frequent antecedent of literacy problems and both may be linked to phonological impairment. However, while several studies have examined the relationship between language delay and reading impairment, relatively few have focused on spelling. In this study, spelling performance of 28 children with developmental dyslexia (DD), 14 children with a history of language delay (LD), and 14 children without (NoLD) and 28 control participants were examined. Spelling was investigated by a writing to dictation task that included orthographically regular stimuli (word and non-words), as well as words with unpredictable transcription. Results indicated that all dyslexic participants underperformed compared to controls on both regular and unpredictable transcription stimuli, but LD performance was generally the worst. Moreover, spelling impairment assumed different characteristics in LD and NoLD children. LD children were more sensitive to acoustic-to-phonological variables, showing relevant failure especially on stimuli containing geminate consonants but also on polysyllabic stimuli and those containing non-continuant consonants. Error analysis confirmed these results, with LD children producing a higher rate of phonological errors respect to NoLD children and controls. Results were coherent with the hypothesis that among dyslexic children, those with previous language delay have more severe spelling deficit, suffering from defective orthographic lexical acquisition together with long-lasting phonological difficulties.