Sex differences in clustering and switching in verbal fluency tasks

Semantic verbal fluency in native speakers of Turkish: a systematic review of category use, scoring metrics and normative data in healthy individuals

INTRODUCTION

Semantic verbal fluency (SVF) is a widely used measure of frontal executive function and access to semantic memory. SVF scoring metrics include the number of unique words generated, perseverations, intrusions, semantic cluster size and switching between clusters, and scores vary depending on the language the test is administered in. In this paper, we review the existing normative data for Turkish, the main metrics used for scoring SVF data in Turkish, and the most frequently used categories.

METHOD

We conducted a systematic review of peer-reviewed papers using Medline, EMBASE, PsycInfo, Web of Science, and two Turkish databases, TR-Dizin and Yok-Tez. Included papers contained data on the SVF performance of healthy adult native speakers of Turkish, and reported the categories used. Versions of the SVF that required participants to alternate categories were excluded. We extracted and tabulated demographics, descriptions of groups, metrics used, categories used, and sources of normative data. Studies were assessed for level of detail in reporting findings.

RESULTS

1400 studies were retrieved. After deduplication, abstract, full text screening, and merging of theses with their published versions, 121 studies were included. 114 studies used the semantic category "animal", followed by first names (N = 14, 12%). All studies reported word count. More complex measures were rare (perseverations: N = 12, 10%, clustering and switching: N = 5, 4%). Four of seven normative studies reported only word count, two also measured perseverations, and one reported category violations and perseverations. Two normative studies were published in English.

CONCLUSIONS

There is a lack of normative Turkish SVF data with more complex metrics, such as clustering and switching, and a lack of normative data published in English. Given the size of the Turkish diaspora, normative SVF data should include monolingual and bilingual speakers. Limitations include a restriction to key English and Turkish databases.

Differential predictability of cognitive profiles from brain structure in older males and females

Structural brain imaging parameters may successfully predict cognitive performance in neurodegenerative diseases but mostly fail to predict cognitive abilities in healthy older adults. One important aspect contributing to this might be sex differences. Behaviorally, older males and females have been found to differ in terms of cognitive profiles, which cannot be captured by examining them as one homogenous group. In the current study, we examined whether the prediction of cognitive performance from brain structure, i.e. region-wise grey matter volume (GMV), would benefit from the investigation of sex-specific cognitive profiles in a large sample of older adults (1000BRAINS; N = 634; age range 55-85 years). Prediction performance was assessed using a machine learning (ML) approach. Targets represented a) a whole-sample cognitive component solution extracted from males and females, and b) sex-specific cognitive components. Results revealed a generally low predictability of cognitive profiles from region-wise GMV. In males, low predictability was observed across both, the whole sample as well as sex-specific cognitive components. In females, however, predictability differences across sex-specific cognitive components were observed, i.e. visual working memory (WM) and executive functions showed higher predictability than fluency and verbal WM. Hence, results accentuated that addressing sex-specific cognitive profiles allowed a more fine-grained investigation of predictability differences, which may not be observable in the prediction of the whole-sample solution. The current findings not only emphasize the need to further investigate the predictive power of each cognitive component, but they also emphasize the importance of sex-specific analyses in older adults.

Comparison of verbal fluency performance in Kannada-speaking adults with and without euthymic bipolar disorder type 1

Individuals with euthymic bipolar disorder (BD) type I exhibit deficits in executive functions. Although less explored in the BD population, the tasks of verbal fluency (VF) have shown great potential in understanding semantic organization. This study provides an extensive exploration across the letter and semantic VF tasks in 27 demographically matched euthymic BD-I and healthy controls (HC). The groups were compared on measures of the total number of correct words (TNCW), temporal pattern analysis, number of clusters (NC), mean cluster size (MCS), number of switches (NS), and error pattern. An overall reduction in letter fluency scores (the TNCW, number of switches, and NC) as compared to semantic fluency scores was noted for both groups, with a significantly greater decrease in the BD-1 group. The MCS and temporal pattern were relatively similar across the two groups. The influence of education with no gender difference was observed between groups with error types prevalent in both groups. The study findings call attention toward assessing the VF performance in persons with BD in terms of error production and the strategies employed (clustering-switching).

Clustering and Switching in Semantic Verbal Fluency: Their Development and Relationship with Word Productivity in Typically Developing Greek-Speaking Children and Adolescents

Performance in semantic verbal fluency (SVF) tasks, mainly measured by the number of words of a particular semantic category produced within a limited time, is a widely accepted measure of cognitive functioning used in the neuropsychological assessment of children and adults. Two strategic processes, Clustering and Switching (C&S) have been proposed to underlie fluency processes and affect performance in the task. However, few studies have reported on the development of those cognitive strategies and their relationship with word productivity in typically developing children. Even fewer studies have covered a broad developmental period from preschool to adolescence or measured the effect of contextual factors in this relationship. Based on a sample of 472 typically developing Greek-speaking children aged 4;0 to 16;11 years, we investigated the development of SVF performance and reported on the degree to which it is affected by C&S strategies, children's sex, and level of parental education. Results revealed a large effect of age on word productivity and on the use of C&S strategies. Two switching factors (number of clusters and number of switches) and two clustering factors (mean cluster size and a novel measure, maximum cluster size), appeared to be significantly associated with word productivity, with the largest effect being attributed to the two switching factors. C&S factors, together with children's age and parental education, predicted 91.7% of the variance in the SVF score. Children's sex was not found to have a significant effect on either word productivity or C&S strategies. Results are discussed for their theoretical implications on the strategic processes underlying word production in typically developing children.

Systematic administration and analysis of verbal fluency tasks: Preliminary evidence for reliable exploration of processes underlying task performance

Verbal fluency (VF) tasks are typically scored by the number of acceptable words generated within an allotted time (i.e., total score). However, total scores do not provide insight into verbal and executive processes underlying VF task performance. Further analyses have been implemented to increase the analytical power of VF tasks, but systematic scoring guidelines are needed. We generated instructions for administration, scoring, and analyses of total scores, errors, temporal parameters, clustering, and switching with strong inter-rater reliability. To investigate the reliability of the proposed analysis, we modeled the performance of Finnish-speaking older adults (N = 50) in phonemic (/k/, /a/, and /p/) and semantic (animals) categories. Our results are in line with previous studies: We observed a higher performance on semantic than phonemic fluency (p ≤ 0.001, d = 0.91) and significant effects for education (p ≤ 0.001, d = 1.11) and gender (p ≤ 0.001, d = -1.11), but not for age (p = 0.10, d = 0.48). Most errors were repetitions. Performance declined over the allotted time frame as measured in 15-s segments (all ps < 0.001 with medium to large effect sizes). Task congruent clustering and switching were productive strategies (all ps < 0.001 with large effect sizes), and participants generated task discrepant clusters in both phonemic (p = 0.004, d = 0.69) and semantic tasks (p = 0.66, d = 0.18). The results substantiate the proposed method, providing evidence that these guidelines are a reliable starting point for VF task performance analyses in various clinical populations investigating VF task performance in depth.

Clustering and Switching on verbal fluency tests in elementary school children with and without learning difficulties

PURPOSE

Evaluate the performance in the Semantic and Phonemic Verbal Fluency tests in relation to the cognitive components of clustering and switching and explore the changes in development in elementary school.

METHODS

Participants were 68 children from the 2nd to 5th grade of elementary school of a public school in the municipality of Santo André, divided into two groups, Learning Difficulty (LD) and Typical Development (TD).

RESULTS

The Verbal Fluency tests were compared for the number of clusters, mean size of the clusters, and number of switches. All variables compared showed a statistically significant higher score for Semantic Verbal Fluency. Means and standard deviations of the same variables for year and group effect were realized in both Verbal Fluency tests. A statistically significant difference was observed only for the total number of clusters in the Semantic Verbal Fluency test for group effect, with the best performance of the TD group. A high correlation was observed between the total number of correct answers with the total number of clusters and number of switches in both Verbal Fluency tests. In addition, a correlation was observed between the total number of correct answers and the mean size of the clusters only in the Phonemic Verbal Fluency. Linear regression analysis showed greater variance for the total number of clusters, making it more predictable for performance in both verbal fluency tests.

CONCLUSION

Verbal Fluency tests may be sensitive and predictive for the identification of possible differences in school performance associated with reading.

Effects of age, gender, and education on task performance and prefrontal cortex processing during emotional and non-emotional verbal fluency tests

The emotional semantic fluency test (SFT) is an emerging verbal fluency test that requires controlled access to emotional lexical information. Currently, how demographic variables influence neurocognitive processing during this test remains elusive. The present study compared the effects of age, gender, and education on task performance and prefrontal cortex (PFC) processing during the non-emotional and emotional SFTs. One-hundred and thirty-three Cantonese-speaking adults aged 18-79 performed the non-emotional and emotional SFTs while their PFC activation was measured using functional near-infrared spectroscopy. Results showed that more education predicted better non-emotional SFT performance, whereas younger age, being female, and more education predicted better emotional SFT performance. Only age significantly affected PFC activation during the SFTs, and the effect was comparable between the two SFTs. Thus, compared with its non-emotional analog, the emotional SFT is influenced by overlapping yet distinct demographic variables. There is a similar age-related reorganization of PFC function across SFT performances.

Women and men have a similar potential for malevolent creativity - But their underlying brain mechanisms are different

Research interest in gender differences in aggression and creative ideation cumulates in the phenomenon of malevolent creativity. Taking another critical step in understanding malevolent creativity, we investigated gender differences in brain activation and functional coupling of cortical sites in the EEG alpha band while n = 88 women and men purposefully generated malevolent creative ideas for taking revenge on others. Results showed that malevolent creativity performance between the genders was similar; however, their underlying EEG patterns were markedly different. While women exhibited a steep decrease of task-related alpha power from frontal to left central-temporal, men's malevolent creative ideation was characterized by a more diffuse pattern of task-related alpha power changes, along with decreased frontal-central coupling. Per interpretation, women's malevolent creative thinking may more strongly rely on controlled semantic memory retrieval and novel re-combination of social/relationship information, while men may utilize more automatic motor-related imagery that may predominantly facilitate physical revenge ideation. Our findings add novel evidence to the idea that women and men engage different neurocognitive strategies to achieve similar creative performance and may help to further illuminate the darker side of creative ideation.

Mental rotation, episodic memory, and executive control: Possible effects of biological sex and oral contraceptive use

Oral contraceptives (OCs) are one of the most common forms of hormonal birth control. A small literature suggests that OC use may affect visuospatial ability, episodic memory, and executive control. However, previous studies have been criticized for small sample sizes and the use of different, single cognitive tests. We investigated the degree to which biological sex and OC use might affect individual mental rotation, episodic memory, and executive control in a large sample of healthy, young adults (N = 155, including 52 OC users, 53 naturally cycling females, and 50 males) tested individually over videoconference. To measure cognition, we used a set of neuropsychological tasks inspired by Glisky and colleagues' two-factor episodic memory and executive control battery, from which two composite scores (based on principal component analysis) were derived for each participant. Our pre-registered analysis revealed a clear female advantage in episodic memory, independent of OC use. In an exploratory analysis, gist memory was elevated in OC users. Interestingly, we found no significant sex-related differences nor effects of OC use on mental rotation or executive control. Duration of OC use was also not related to any of our cognitive measures. These results suggest that the use of combined, monophasic OCs does not lead to many significant changes in cognition in young adults, although young females overall may have better episodic memory than young males. Additional studies, including longitudinal designs and looking in more detail at the menstrual cycle and OC use history, will further clarify the effects of different types of OCs and their duration of use on different aspects of cognition.

Sex/Gender Differences in Verbal Fluency and Verbal-Episodic Memory: A Meta-Analysis

Women are thought to fare better in verbal abilities, especially in verbal-fluency and verbal-memory tasks. However, the last meta-analysis on sex/gender differences in verbal fluency dates from 1988. Although verbal memory has only recently been investigated meta-analytically, a comprehensive meta-analysis is lacking that focuses on verbal memory as it is typically assessed, for example, in neuropsychological settings. On the basis of 496 effect sizes and 355,173 participants, in the current meta-analysis, we found that women/girls outperformed men/boys in phonemic fluency (ds = 0.12-0.13) but not in semantic fluency (ds = 0.01-0.02), for which the sex/gender difference appeared to be category-dependent. Women/girls also outperformed men/boys in recall (d = 0.28) and recognition (ds = 0.12-0.17). Although effect sizes are small, the female advantage was relatively stable over the past 50 years and across lifetime. Published articles reported stronger female advantages than unpublished studies, and first authors reported better performance for members of their own sex/gender. We conclude that a small female advantage in phonemic fluency, recall, and recognition exists and is partly subject to publication bias. Considerable variance suggests further contributing factors, such as participants' language and country/region.

Stereotypes and self-reports about spatial cognition: Impact of gender and age

Cognitive stereotypes with regard to gender are prevalent, especially with regard to spatial cognition. However, literature suggests that age, rather than gender has more impact on objective spatial performance. The aim of this study was to create a detailed picture of the extent and direction of stereotypes held in general population. Individual differences in terms of age and gender, as well as age group identification and gender identification were studied in relation to the stereotypes held. In addition, self-reported performance was also considered, to compare stereotype beliefs to beliefs concerning one’s own performance. An online questionnaire was filled out by a large and heterogeneous sample of Dutch participants (N = 980). Results indicate that gender stereotypes concerning spatial abilities are clearly prevalent and held most strongly by male and young individuals. Stereotype beliefs were very similar to the patterns found for self-reported performance for gender, even though this is not supported by findings concerning objective performance. Stereotypes concerning age were largely absent. These findings indicate that the presence of stereotype beliefs and the individual differences in how strong such beliefs are should be considered in educational and clinical settings where spatial performance is evaluated.

Factors Predicting Mental Effort Associated With Verbal Fluency: Cue Types, Switching, and Fear of Negative Evaluation

PURPOSE

Verbal fluency, a task frequently employed in neuropsychological assessment, provides important word productivity data but little information about subjective effort associated with demand monitoring and resource allocation. In two experiments, this study investigated the effects of task variables (semantic vs. phonemic cues; alternating vs. nonalternating conditions) and personal factors (fear of negative evaluation and trait anxiety) on subjective effort for a wide variety of verbal fluency tasks in neurotypical individuals.

METHOD

Twenty-one adults completed eight verbal fluency tasks in Experiment 1. The tasks were selected to examine effort reported for verbal fluency that differed in (a) cue types and (b) the disruptions of clustering strategies. In Experiment 2, a separate group of 50 adults completed two verbal fluency tasks twice in separate sessions. Participants also completed social-emotional measures including fear of negative evaluation and trait anxiety. Working memory was assessed as a control variable.

RESULTS

Experiment 1 showed greater effort for completing semantic than phonemic cue tasks and greater effort for alternating than nonalternating conditions. Alternating semantic verbal fluency yielded the greatest effort among all tasks. Differences in effort could not be accounted for by performance alone. Experiment 2 showed that greater fear toward negative evaluation was associated with greater effort. The relationship between fear and effort was not related to trait anxiety or moderated by performance levels or repeated testing.

CONCLUSIONS

Knowledge about factors that impact subjective effort in neurotypical individuals is fundamental to accurate interpretation of effort reported by clinical populations. This study demonstrated the multifaceted nature of subjective effort that could not be accounted for by performance alone. In addition to task variables, effort assessment needs to consider the impact of social-emotional factors such as fear toward negative evaluation.

Gender differences in the association between environment and psychosis

Various environmental exposures have been associated with psychosis spectrum disorder. However, the role of gender in this association has received little attention. Therefore, we conducted a systematic review to evaluate gender-related differences and identified 47 research articles investigating the associations of psychosis with childhood adversity, substance use, urbanicity, migration, season of birth, and obstetric complication in the PubMed database. The findings suggest that childhood abuse may be more strongly associated with a risk to develop psychosis and an earlier age at onset of illness in women than in men. Furthermore, childhood adversity has been associated with the severity of different symptom dimensions in men and women. Growing up in an urban environment and immigration are more strongly associated with psychosis risk in men than in women. Despite a higher prevalence of substance abuse comorbidity in men diagnosed with psychotic disorders, it appears that the association between substance use and psychosis risk may be stronger in women. These findings should be evaluated with caution considering several methodological limitations, limited number of studies, and lack of consistency across results. Overall, although further investigation is needed, our review shows that gender-related differences in the associations of environmental exposures with psychosis expression may exist.

Exploring the sex and gender correlates of cognitive sex differences

The correlates of cognitive sex differences are yet to be fully understood. Many biological and psychosocial factors modulate these cognitive abilities leading to mixed results in the scientific literature. The current study aims to explore the different parameters potentially influencing cognitive abilities acting in synergy. Sex and gender correlates of cognitive functioning were assessed in a sample of individuals ages 18 to 45 years (N = 87) from diverse sexual orientations. Sex hormones were assessed via saliva samples at four timepoints throughout the testing. Gender roles, sexual orientation and socio-demographics were measured via self-report questionnaires. Participants completed mental rotation and verbal fluency tasks. Men performed better than women at mental rotation, while no significant difference was found for verbal fluency. Significant positive associations were observed between estradiol and word fluency for the naturally cycling women compared to the women using oral contraception. While controlling for sex hormones, a significant interaction effect of sex by gender roles was identified for mental rotation among masculine women. These exploratory results suggest an effect principally driven by sex and sex hormones on cognitive performance that will need to be furthered with larger studies.

Revisiting the Effects of Gender Diversity in Small Groups on Divergent Thinking: A Large-Scale Study Using Synchronous Electronic Brainstorming

Numerous studies have examined the effects of gender diversity in groups on creative performance, and no clear effect has been identified. Findings depend on situational cues making gender diversity more or less salient in groups. A large-scale study on two cohorts (N = 2,261) was conducted among business students to examine the impact of the gender diversity in small groups on divergent thinking in an idea-generation task performed by synchronous electronic brainstorming. Participants were automatically randomized in three- or four-member groups to generate ideas during 10 min on a gendered or neutral task. Then, five categories of groups where the proportion of men/women in groups varied from three/four men to three/four women were compared to examine creative performance on three divergent thinking measures (fluency, flexibility, and originality). A Multivariate Generalized Linear Mixed Model (mGLMM) showed greater fluency in all-women groups than in other groups (except mixed-gender groups composed of two men and two women), and more specifically "solo" groups composed of a single woman/man among a majority of men/women. For flexibility and originality, the superiority of all-women groups was found only in comparison to "solo" groups composed of a single woman. As gender differences are more salient in "solo" groups than in other groups faultlines may appear in groups, leading to a deleterious impact on creative performance.

The Effect of Mental Fatigue and Gender on Working Memory Performance during Repeated Practice by Young and Older Adults

Working memory (WM) is one of the most investigated cognitive functions albeit the extent to which individual characteristics impact on performance is still unclear, especially when older adults are involved. The present study considers repeated practice of a visual N-Back task with three difficulty levels (1-, 2-, and 3-Back) in healthy young and older individuals. Our results reveal that, for both age groups, the expected mental fatigue was countered by a learning effect, in terms of accuracies and reaction times, which turned out to benefit females more than males, for all three N-Back levels. We conclude that future WM studies, in particular when relying on repeated N-Back sessions, should account for learning effects in relation to mental fatigue and gender, in both young and older adults.

The emotion word fluency test as an embedded performance validity indicator - Alone and in a multivariate validity composite

OBJECTIVE

This project was designed to cross-validate existing performance validity cutoffs embedded within measures of verbal fluency (FAS and animals) and develop new ones for the Emotion Word Fluency Test (EWFT), a novel measure of category fluency.

METHOD

The classification accuracy of the verbal fluency tests was examined in two samples (70 cognitively healthy university students and 52 clinical patients) against psychometrically defined criterion measures.

RESULTS

A demographically adjusted T-score of ≤31 on the FAS was specific (.88-.97) to noncredible responding in both samples. Animals T ≤ 29 achieved high specificity (.90-.93) among students at .27-.38 sensitivity. A more conservative cutoff (T ≤ 27) was needed in the patient sample for a similar combination of sensitivity (.24-.45) and specificity (.87-.93). An EWFT raw score ≤5 was highly specific (.94-.97) but insensitive (.10-.18) to invalid performance. Failing multiple cutoffs improved specificity (.90-1.00) at variable sensitivity (.19-.45).

CONCLUSIONS

Results help resolve the inconsistency in previous reports, and confirm the overall utility of existing verbal fluency tests as embedded validity indicators. Multivariate models of performance validity assessment are superior to single indicators. The clinical utility and limitations of the EWFT as a novel measure are discussed.

Executive-function tasks in patients with mild cognitive impairment and Alzheimer's Disease: Effects of decline and gender

It is exceedingly rare to find studies that analyze the effect of gender differences in executive-function tasks in normal cognitive aging, Mild Cognitive Impairment (MCI) and Alzheimer's Disease (AD). The objective of the present study was to analyze the mean differences in performance in four executive-function tasks, the Clock Drawing Test verbal-command, Clock Drawing Test-copy, Phonetic Fluency Test and Trail Making Test-A, according to the gender and impairment group variables. A total of 90 participants (30 patients with Alzheimer's Disease, 30 patients with Mild Cognitive Impairment, and 30 healthy elderly participants; 50% men and 50% women in each group) took part in the study. As expected, the results showed a main effect of the group in most tasks, with a progressively worse performance according to cognitive impairment. Regarding the effect of gender, there were no significant differences in the Mild Cognitive Impairment and healthy elderly groups, but a significantly higher performance of women compared to men was found in the Alzheimer's group. The clinical and theoretical implications of these results are discussed. In particular, the abnormal performance of women with Alzheimer's in the sample may be related to a possible cognitive reserve due to social and educational background in their sociocultural and generational context.

Differences in Neuropsychological Performance between Refugee and Non-Refugee Children in Palestine

Neuropsychological studies on refugee children are scarce, but there are even less in the case of Palestinian children. This work aims to study the neuropsychological performance of Palestinian refugee children in Palestine compared to other Palestinian children living outside refugee camps. A comprehensive Neuropsychological battery was administrated to 584 Palestinian school children (464 refugees and 120 non-refugees) aged 6, 7, and 8 years old. Results showed that non-refugee children outperformed refugee children in sustained attention, verbal comprehension, verbal memory, and visual memory. This study is the first to have performed a comprehensive neuropsychological assessment, based on a standardized and validated battery with the Palestinian refugee children. It supports professionals in their evaluation of neurodevelopment and neuropsychological alterations in refugee and non-refugee children in Palestine.

Psychoneuroendocrine protocol to comprehensively study sexually dimorphic cognition

Background

A large body of research provides evidence for sex differences in cognitive abilities. These sex differences stem from the interplay between biological sex (e.g., birth-assigned sex, sex hormones) and psychosocial gender (e.g., gender identity, gender-roles, sexual orientation). Literature remains rather mixed with regards to the magnitude of sex and gender effects on cognitive abilities and mental health. Growing evidence shows that sex hormone assessment combined with measures of psychosocial gender may be fundamental to comprehensively understand individual differences in sexually dimorphic cognitive abilities.

Objectives

This study protocol describes a sexually dimorphic cognitive battery to assess the influence of sex hormones on performance. In parallel, we aim to assess the inter-related effects that biological sex and psychosocial gender-based factors exert on cognition and mental health.

Methods

Our projected sample includes 180 adult participants who are at least 18 years old. Sub-groups will be recruited based on birth-assigned sex, gender identity, and sexual orientation. Biological measures will be collected via salivary samples throughout testing to include sex hormones (testosterone, estradiol and progesterone) and stress hormones (cortisol). Demographic and psychosocial variables will be measured through self-report questionnaires. Participants will be required to complete eight classic cognitive tasks that assess a variety of cognitive domains in a 2-h testing session.

Results and future directions

Results from this study provides unique insights into the correlates of cognitive sex differences and gender diversity. This will give us solid ground to further investigate these influences in clinical populations in which sex hormones and cognitive functioning are often altered.

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Cognition is modulated by multiple sex and gender factors.

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Cognitive abilities will be assessed among 180 adults representing diverse sexual orientations and gender identities.

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This protocol aims to nuance the effects of sex hormones in contrast to those of socio-cultural gender.

Comprehensive verbal fluency features predict executive function performance

Semantic verbal fluency (sVF) tasks are commonly used in clinical diagnostic batteries as well as in a research context. When performing sVF tasks to assess executive functions (EFs) the sum of correctly produced words is the main measure. Although previous research indicates potentially better insights into EF performance by the use of finer grained sVF information, this has not yet been objectively evaluated. To investigate the potential of employing a finer grained sVF feature set to predict EF performance, healthy monolingual German speaking participants (n = 230) were tested with a comprehensive EF test battery and sVF tasks, from which features including sum scores, error types, speech breaks and semantic relatedness were extracted. A machine learning method was applied to predict EF scores from sVF features in previously unseen subjects. To investigate the predictive power of the advanced sVF feature set, we compared it to the commonly used sum score analysis. Results revealed that 8 / 14 EF tests were predicted significantly using the comprehensive sVF feature set, which outperformed sum scores particularly in predicting cognitive flexibility and inhibitory processes. These findings highlight the predictive potential of a comprehensive evaluation of sVF tasks which might be used as diagnostic screening of EFs.

Cognitive profiles in older males and females

Males and females are subject to differences in cognitive processing strategies, i.e. the way males and females solve cognitive tasks. So far primarily reported for younger adults, this seems to be especially important in older adults, who also show sex differences in cognitive impairments. Therefore, the aim of the current study was to examine the older adult population with respect to cognitive profiles derived from a large variety of cognitive functions. Using an exploratory component analysis with consecutive confirmatory factor analysis in a sample of 676 older adults, neuropsychological performance data in a variety of cognitive domains was decomposed into cognitive components. A general cognitive profile based on the whole group fits unequally well on the two sexes. Importantly, cognitive profiles based on either males or females differ in terms of their composition of cognitive components, i.e. three components in males versus four components in females, with a generally better model fit in females. Thus, related to the established differences in processing styles between males and females the current study found a rather decomposed (or local) cognitive profile in females while males seem to show a holistic (or global) cognitive profile, with more interrelations between different cognitive functions.

Genetic and Environmental Influences on Semantic Verbal Fluency Across Midlife and Later Life

Despite the relevance of semantic fluency measures to risk for dementia and psychiatric disorders, little is known about their genetic and environmental architecture in mid-to-late life. Participants represent 21,684 middle-aged and older adult twins (M = 60.84 years, SD = 11.21; Range 40-89) from six studies from three countries participating in the Interplay of Genes and Environment across Multiple Studies (IGEMS) consortium. All completed the same measure of semantic fluency (naming animals in 60 seconds). Results revealed small-to-moderate phenotypic associations with age and education, with education more strongly and positively associated with fluency performance in females than males. Heritability and environmental influences did not vary by age. Environmental variance was smaller with higher levels of education, but this effect was observed only in males. This is the largest study to examine the genetic and environmental architecture of semantic fluency, and the first to demonstrate that environmental influences vary based on levels of education.

An Examination of Study Time Allocation as a Contributor to Sex Differences in Multitrial Verbal Learning Performance

Researchers have noted sex differences in verbal memory performance with females showing a memory superiority effect. Research paradigms have largely incorporated experimenter-timed materials. Therefore, the extent to which self-regulating study time influences this pattern of sex differences is unclear. The researcher reexamined data from a published paper to determine whether sex differences in multitrial verbal learning are minimized when individuals self-regulate their study time, or if sex differences would still remain. The results from this study showed that females outperformed males on subsequent test trials, and they allocated more study time. Controlling for the influence of study time allocation reduced or eliminated sex differences in memory performance, and only study time allocation was related to whether items were gained or lost across trials. These findings suggest the importance of self-regulated learning in reducing sex differences on a verbal memory task and the contribution of study time allocation to memory performance.

Normative data for Verbal Fluency and Object Naming Tests in a sample of European Portuguese adult population

The purpose of the present study was to calculate the construct validity, internal consistency and normative data of the Phonological Verbal Fluency Test (letters F, A, S, and M), Semantic Verbal Fluency Test (Animals, Fruits and Professions categories), and Boston Naming Test (short and standard version), and to generate normative data for these tests after adjusting for age, education, and sex. A sample of 293 European Portuguese adults participated in the study. Results showed adequate construct validity and internal consistency for all of the tests and the final multiple regression models found that age and education were significantly associated with P-VFT (letters F, A, S, and M), S-VFT (Animals, Fruits and Professions categories), and BNT performance. Sex was only found to have an effect on the fruit category, with women scoring higher than men. The normative data provided in this study will contribute to improving the clinical practice of neuropsychology in Portugal.

Recruiting the right hemisphere: Sex differences in inter-hemispheric communication during semantic verbal fluency

Sex differences in cognitive functions are heavily debated. Recent work suggests that sex differences do stem from different processing strategies utilized by men and women. While these processing strategies are likely reflected in different brain networks, so far the link between brain networks and processing strategies remains speculative. In the present study we seek for the first time to link sex differences in brain activation patterns to sex differences in processing strategies utilizing a semantic verbal fluency task in a large sample of 35 men and 35 women, all scanned thrice. For verbal fluency, strategies of clustering and switching have been described. Our results show that men show higher activation in the brain network supporting clustering, while women show higher activation in the brain network supporting switching. Furthermore, converging evidence from activation results, lateralization indices and connectivity analyses suggests that men recruit the right hemisphere more strongly during clustering, but women during switching. These results may explain findings of differential performance and strategy-use in previous behavioral studies.

Executive functions predict verbal fluency scores in healthy participants

While there is a clear link between impairments of executive functions (EFs), i.e. cognitive control mechanisms that facilitate goal-directed behavior, and speech problems, it is so far unclear exactly which of the complex subdomains of EFs most strongly contribute to speech performance, as measured by verbal fluency (VF) tasks. Furthermore, the impact of intra-individual variability is largely unknown. This study on healthy participants (n = 235) shows that the use of a relevance vector machine approach allows for the prediction of VF performance from EF scores. Based on a comprehensive set of EF scores, results identified cognitive flexibility and inhibition as well as processing speed as strongest predictors for VF performance, but also highlighted a modulatory influence of fluctuating hormone levels. These findings demonstrate that speech production performance is strongly linked to specific EF subdomains, but they also suggest that inter-individual differences should be taken into account.

Sex Differences in Verbal Fluency Among Young Adults

Verbal fluency tasks have been used as tools to measure various cognitive processes, such as executive functions, memory, and language. Sex differences in verbal fluency performance have been mostly investigated in population studies. Little of this research has focused on young adults. The goal of this study was to assess the impact of sex and task category on word production and verbal strategies (i.e., cluster size and switches) in young adults. The phonemic (letter “k”, letter “f”) and semantic (animals, fruits, sharp objects) fluency measures were used. Men and women were compared in terms of the number of produced words and the use of verbal strategies (number of switches and mean cluster size controlled for produced words). Results revealed subtle sex differences in verbal fluency in young adults. Men performed slightly better in semantic fluency, producing more words, while there were no sex differences in verbal strategies. There were also no sex differences in word production and verbal strategies in the phonemic fluency tasks. Furthermore, there were differences in the number of produced words, mean cluster sizes, and switches between semantic tasks as well as between phonemic tasks. These results can be interpreted in the context of potential differences in mental lexicon and social roles. Moreover, our results suggest that assessment of verbal strategies and overall word production may be important in the context of sex differences in verbal fluency among young adults as well as in neuropsychological diagnosis

Relations Among Executive Function, Decoding, and Reading Comprehension: An Investigation of Sex Differences

In the current investigation, we used structural equation mediation modeling to examine the relations between executive function (indexed by measures of working memory, shifting, and inhibition), decoding ability, and reading comprehension in a sample of 298 6- to 8-year-old children (N =132 and 166 for boys and girls, respectively). Results for the full sample indicated that executive function was mediated by decoding ability. When sex was examined as a moderator of these associations, there was evidence for a trend suggesting that direct relations between executive function and reading comprehension were stronger for girls compared to boys; no significant differences were found for other direct and indirect relations. Taken together, these findings highlight the importance of executive function in supporting underlying integrative processes associated with reading comprehension and emphasize the need to further consider the role of executive function in relation to reading.

Spatial skills

Spatial skills represent an important part of our cognitive processes and have been widely studied in the last decades. The term "spatial skills" includes several abilities, some of them clearly sexually dimorphic. Thus men usually perform better than women in mental rotation and spatial orientation tasks, whereas women outperform men in object location memory tests. Skills like visualization and perception could account for these differences, but they could also be modulated by the cognitive style. Obviously, disease can interfere in certain brain structures underlying learning and memory, thus altering spatial abilities in both genders. In this chapter, spatial skills and sexual dimorphism are briefly reviewed, focusing on processes underlying performance as well as models used to explain how we perceive information from the environment. The chapter also includes references to the brain, providing some cues regarding the anatomic regions underlying some of these behaviors.

Sex differences in cognition and aging and the influence of sex hormones

Sex differences in cognitive functioning have been consistently reported in some cognitive tasks, with varying effect sizes. The most consistent findings in healthy adults are sex differences in the areas of mental rotation and aspects of attention and verbal memory. Sex differences in the vulnerability and manifestation of several psychiatric and neurologic diseases that involve cognitive disruption provide strong justification to continue investigating the social and biologic influences that underpin sex differences in cognitive functioning across health and disease. The biologic influences are thought to include genetic and epigenetic factors, sex chromosomes, and sex hormones. Sex steroid hormones that regulate reproductive function have multiple effects on the development, maintenance, and function of the brain, including significant effects on cognitive functioning. The aim of the current chapter is to provide a theoretical review of sex differences across different cognitive domains in adulthood and aging, as well as provide an overview on the role of sex hormones in cognitive function and cognitive decline.

Associations between memory and verbal fluency tasks

Previous studies have provided inconsistent evidence concerning the association between delayed retrieval of story information from long-term memory and retrieval of words on verbal fluency tasks. The current study looks for shared retrieval mechanisms in these tasks from childhood to old age. Three-hundred and eighty participants (ages 5-91) performed tasks of story recall, digit span, phonemic fluency, and semantic fluency. Significant correlations between delayed story recall and both fluency tasks emerged in all age groups, and the contribution of delayed story recall to fluency performance remained significant when analyzing the combined effects of story recall and digit span. These findings suggest that retrieval of information through story recall and retrieval of words on fluency tasks may share similar cognitive components.

Sex-specific norms for verbal memory tests may improve diagnostic accuracy of amnestic MCI

OBJECTIVE

To examine whether the use of sex-specific norms and cut scores to identify memory impairment improves diagnostic accuracy of amnestic mild cognitive impairment (aMCI) compared to non-sex-specific (typical) norms/cut scores given the female advantage in verbal memory.

METHODS

We calculated sex-specific and typical norms/cut scores (age and education specific) for impairment on the Rey Auditory Verbal Learning Test in the Mayo Clinic Study of Aging. Norms/cut scores were applied to 453 women and 532 men from the Alzheimer's Disease Neuroimaging Initiative. We compared sex differences in rates of aMCI (Jak/Bondi criteria) for sex-specific vs typical norms/cut scores. Using sex-specific cut scores as the true condition and typical cut scores as the predicted condition, we categorized participants as true positives (TPs), false positives (FPs), true negative (TNs), or false negative (FNs). In cross-sectional analyses within sex, we compared positivity rates of CSF hyperphosphorylated tau/β-amyloid (Aβ) and cortical Aβ deposition ([¹⁸F]AV45 PET) and APOE ε4 frequency among diagnostic comparison groups.

RESULTS

The frequency of aMCI was higher in men when using typical norms/cut scores. Using sex-adjusted norms/cut scores led to the identification of 10% FNs (missed aMCI cases) among women and 10% FPs among men. Biomarker analyses supported the hypothesis that sex-specific diagnostic criteria improves diagnostic accuracy. Biomarkers rates were higher in FNs vs TNs and similar in FNs and TPs. Biomarker rates were lower in FPs vs TPs and similar between FPs and TNs.

CONCLUSION

Results suggest that non-sex-specific aMCI diagnostic criteria led to a 20% diagnostic error rate. Accounting for sex differences in verbal memory performance may improve aMCI classification.

Sex, Age, and Handedness Modulate the Neural Correlates of Active Learning

BACKGROUND

Self-generation of material compared to passive learning results in mproved memory performance; this may be related to recruitment of a fronto-temporal encoding network. Using a verbal paired-associate learning fMRI task, we examined the effects of sex, age, and handedness on the neural correlates of self-generation.

METHODS

Data from 174 healthy English-speaking participants (78M, 56 atypically handed; ages 19-76) were preprocessed using AFNI and FSL. Independent component analysis was conducted using GIFT (Group ICA fMRI Toolbox). Forty-one independent components were temporally sorted by task time series. Retaining correlations (r > 0.25) resulted in three task-positive ("generate") and three task-negative ("read") components. Using participants' back-projected components, we evaluated the effects of sex, handedness, and aging on activation lateralization and localization in task-relevant networks with two-sample t-tests. Further, we examined the linear relationship between sex and neuroimaging data with multiple regression, covarying for scanner, age, and handedness.

RESULTS

Task-positive components identified using ICA revealed a fronto-parietal network involved with self-generation, while task-negative components reflecting passive reading showed temporo-occipital involvement. Compared to older adults, younger adults exhibited greater task-positive involvement of the left inferior frontal gyrus and insula, whereas older adults exhibited reduced prefrontal lateralization. Greater involvement of the left angular gyrus in task-positive encoding networks among right-handed individuals suggests the reliance on left dominant semantic processing areas may be modulated by handedness. Sex effects on task-related encoding networks while controlling for age and handedness suggest increased right hemisphere recruitment among males compared to females, specifically in the paracentral lobe during self-generation and the suparmarginal gyrus during passive reading.

IMPLICATIONS

Identified neuroimaging differences suggest that sex, age, and handedness are factors in the differential recruitment of encoding network regions for both passive and active learning.

Five-factor model personality traits and verbal fluency in 10 cohorts

Personality traits, such as Neuroticism and Conscientiousness, are associated with cognitive outcomes across the life span, including cognitive function in young adulthood and risk of cognitive impairment and dementia in old age. Research on personality and age-related cognition has focused primarily on memory-related tasks and outcomes. The purpose of this research is to address the relation between Five Factor Model personality traits and another critical marker of cognitive function that has received less attention-verbal fluency. We examine this relation across adulthood in 10 cohorts (11 samples) that totaled more than 90,000 participants (age range 16-101). Participants in all samples reported on their personality traits and completed at least one fluency task (semantic and/or letter). A meta-analysis of semantic fluency (N = 86,044) indicated that participants who scored lower in Neuroticism, and higher in Extraversion, Openness, and Conscientiousness, retrieved more words, independent of age, gender, and education. These associations generally replicated for the letter fluency task (3 samples; N = 11,551). Moderation analysis indicated that the associations between personality and semantic fluency were stronger in older samples (except for Openness) and among individuals with lower education. This pattern suggests that these associations are stronger in groups vulnerable to severe cognitive impairment. Personality traits have pervasive associations with fluency tasks that are replicable across samples and age groups. (PsycINFO Database Record (c) 2019 APA, all rights reserved).

The influence of age and ASD on verbal fluency networks

BACKGROUND

The integrity and connectivity of the frontal lobe, which subserves fluency, may be compromised by both ASD and aging. Alternate networks often integrate to help compensate for compromised functions during aging. We used network analyses to study how compensation may overcome age-related compromised in individuals with ASD.

METHOD

Participants consisted of middle-aged (40-60; n=24) or young (18-25; n=18) right-handed males who have a diagnosis of ASD, and age- and IQ-matched control participants (n=20, 14, respectively). All performed tests of language and executive functioning and a fluency functional MRI task. We first used group individual component analysis (ICA) for each of the 4 groups to determine whether different networks were engaged. An SPM analysis was used to compare activity detected in the network nodes from the ICA analyses.

RESULTS

The individuals with ASD performed more slowly on two cognitive tasks (Stroop word reading and Trailmaking Part A). The 4 groups engaged different networks during the fluency fMRI task despite equivalent performance. Comparisons of specific regions within these networks indicated younger individuals had greater engagement of the thalamus and supplementary speech area, while older adults engaged the superior temporal gyrus. Individuals with ASD did not disengage from the Default Mode Network during word generation.

CONCLUSION

Interactions between diagnosis and aging were not found in this study of young and middle-aged men, but evidence for differential engagement of compensatory networks was observed.

Parkinson's-adapted cognitive stimulation therapy: feasibility and acceptability in Lewy body spectrum disorders

BACKGROUND

Drug-based therapeutic approaches for Parkinson's disease dementia (PDD) and dementia with Lewy bodies (DLB) are moderately effective and not always tolerated. Tailoring psychosocial approaches in PDD and DLB may offer additional support and improve outcomes. We adapted home-based, care partner-delivered Cognitive Stimulation Therapy (CST) for individuals with PDD or DLB and their care partners (CST-PD).

OBJECTIVES

To evaluate the feasibility, acceptability, and tolerability of CST-PD.

METHODS

This randomised controlled trial used mixed methods, including a process evaluation. People with PDD, DLB or mild cognitive impairment in PD (PD-MCI) and their care partners were randomised to 12 weeks of treatment as usual (TAU) or CST-PD. Outcomes were feasibility of the study conduct (i.e., recruitment, retention rate) and acceptability and tolerability of the intervention. Measures included rating scales, researcher field notes, therapy diaries, and exploratory clinical and care partner efficacy measures.

RESULTS

The recruitment target was met with 76 consenting participant-dyads. Retention in both arms was high at over 70%. More than 90% of dyads undertook discrete sessions greater than 20 min duration, but the average number of sessions completed was lower than the recommended dose. Acceptability ratings (i.e., interest, motivation and sense of achievement) of the intervention were high. Participants reported no serious adverse events related to the intervention.

CONCLUSIONS

The field of psychosocial interventions for PDD and DLB is newly emerging, and we demonstrated that this type of intervention is acceptable and well tolerated. Evaluating its clinical effectiveness in a full-scale randomized controlled clinical trial is warranted.

TRIAL REGISTRATION NUMBER

The trial is a psychosocial intervention with an allocated ISRCTN number 11455062.

Mental health symptoms and verbal fluency in elderly people: Evidence from the Spanish longitudinal study of aging

OBJECTIVES

Depression and loneliness are highly prevalent in old age. Moreover these mental health symptoms adversely affect the verbal fluency of the elderly. We examined the relationship between depression and loneliness with verbal fluency in people aged 50 years or older.

METHOD

Research data were collected during the pilot study of the Longitudinal Aging Study in Spain (ELES) in which a representative sample of non-institutionalized Spanish older people was assessed. Here, the cross-sectional data for 962 participants were analysed using hierarchical regressions, controlling for age, education level, overall cognitive functioning, social networks and satisfaction with family.

RESULTS

Higher levels of cognitive functioning were associated with higher verbal fluency. Females showed higher levels of phonological fluency. Neither depression nor loneliness were significant predictors of phonological fluency but loneliness was a significant predictor of semantic fluency. For mild levels of loneliness, the rate of decline in semantic fluency slows in the oldest ages. In contrast, for severe loneliness the rate of decline in semantic fluency increases in the oldest ages.

CONCLUSIONS

Depressive symptoms, loneliness and cognitive impairment are all prominent in ageing and therefore their impact on ageing needs to be better understood. Early detection of loneliness, along with the implementation of intervention for individuals diagnosed with loneliness is advisable in order to avoid negative repercussions for the verbal fluency of these individuals.

Impact of sex and reproductive status on memory circuitry structure and function in early midlife using structural covariance analysis

Research on age-related memory alterations traditionally targets individuals aged ≥65 years. However, recent studies emphasize the importance of early aging processes. We therefore aimed to characterize variation in brain gray matter structure in early midlife as a function of sex and menopausal status. Subjects included 94 women (33 premenopausal, 29 perimenopausal, and 32 postmenopausal) and 99 demographically comparable men from the New England Family Study. Subjects were scanned with a high-resolution T1 sequence on a 3 T whole body scanner. Sex and reproductive-dependent structural differences were evaluated using Box's M test and analysis of covariances (ANCOVAs) for gray matter volumes. Brain regions of interest included dorsolateral prefrontal cortex (DLPFC), inferior parietal lobule (iPAR), anterior cingulate cortex (ACC), hippocampus (HIPP), and parahippocampus. While we observed expected significant sex differences in volume of hippocampus with women of all groups having higher volumes than men relative to cerebrum size, we also found significant differences in the covariance matrices of perimenopausal women compared with postmenopausal women. Associations between ACC and HIPP/iPAR/DLPFC were higher in postmenopausal women and correlated with better memory performance. Findings in this study underscore the importance of sex and reproductive status in early midlife for understanding memory function with aging.

Influence of age and education on the processing of clustering and switching in verbal fluency tasks

Verbal fluency (VF) is a widely used tool in neuropsychological assessment.

Peripheral oxytocin and vasopressin modulates regional brain activity differently in men and women with schizophrenia

BACKGROUND

Oxytocin (OT) and arginine vasopressin (AVP) exert sexually dimorphic effects on cognition and emotion processing. Abnormalities in these hormones are observed in schizophrenia and may contribute to multiple established sex differences associated with the disorder. Here we examined sex-dependent hormone associations with resting brain activity and their clinical associations in schizophrenia patients.

METHODS

OT and AVP serum concentrations were assayed in 35 individuals with schizophrenia (23 men) and 60 controls (24 men) from the Chicago BSNIP study site. Regional cerebral function was assessed with resting state fMRI by measuring the amplitude of low-frequency fluctuations (ALFF) which are believed to reflect intrinsic spontaneous neuronal activity.

RESULTS

In female patients, lower OT levels were associated with lower ALFF in frontal and cerebellar cortices (p's < 0.05) and in female controls AVP levels were inversely associated with ALFF in the frontal cortex (p = 0.01). In male patients, lower OT levels were associated with lower ALFF in the posterior cingulate and lower AVP levels were associated with lower ALFF in frontal cortex (p's < 0.05). In male controls, lower OT levels were associated with lower ALFF in frontal cortex and higher ALFF in the thalamus (p's < 0.05). There were some inverse ALFF-behavior associations in patients.

CONCLUSIONS

Alterations in peripheral hormone levels are associated with resting brain physiology in a sex-dependent manner in schizophrenia. These effects may contribute to sex differences in psychiatric symptom severity and course of illness in schizophrenia.

Theoretical Modeling of Cognitive Dysfunction in Schizophrenia by Means of Errors and Corresponding Brain Networks

The current evidence of cognitive disturbances and brain alterations in schizophrenia does not provide the plausible explanation of the underlying mechanisms. Neuropsychological studies outlined the cognitive profile of patients with schizophrenia, that embodied the substantial disturbances in perceptual and motor processes, spatial functions, verbal and non-verbal memory, processing speed and executive functioning. Standardized scoring in the majority of the neurocognitive tests renders the index scores or the achievement indicating the severity of the cognitive impairment rather than the actual performance by means of errors. At the same time, the quantitative evaluation may lead to the situation when two patients with the same index score of the particular cognitive test, demonstrate qualitatively different performances. This may support the view why test paradigms that habitually incorporate different cognitive variables associate weakly, reflecting an ambiguity in the interpretation of noted cognitive constructs. With minor exceptions, cognitive functions are not attributed to the localized activity but eventuate from the coordinated activity in the generally dispersed brain networks. Functional neuroimaging has progressively explored the connectivity in the brain networks in the absence of the specific task and during the task processing. The spatio-temporal fluctuations of the activity of the brain areas detected in the resting state and being highly reproducible in numerous studies, resemble the activation and communication patterns during the task performance. Relatedly, the activation in the specific brain regions oftentimes is attributed to a number of cognitive processes. Given the complex organization of the cognitive functions, it becomes crucial to designate the roles of the brain networks in relation to the specific cognitive functions. One possible approach is to identify the commonalities of the deficits across the number of cognitive tests or, common errors in the various tests and identify their common "denominators" in the brain networks. The qualitative characterization of cognitive performance might be beneficial in addressing diffuse cognitive alterations presumably caused by the dysconnectivity of the distributed brain networks. Therefore, in the review, we use this approach in the description of standardized tests in the scope of potential errors in patients with schizophrenia with a subsequent reference to the brain networks.

Not single brain areas but a network is involved in language: Applications in presurgical planning

OBJECTIVES

Language is an important human function, and is a determinant of the quality of life. In conditions such as brain lesions, disruption of the language function may occur, and lesion resection is a solution for that. Presurgical planning to determine the language-related brain areas would enhance the chances of language preservation after the operation; however, availability of a normative language template is essential.

PATIENTS AND METHODS

In this study, using data from 60 young individuals who were meticulously checked for mental and physical health, and using fMRI and robust imaging and data analysis methods, functional brain maps for the language production, perception and semantic were produced.

RESULTS

The obtained templates showed that the language function should be considered as the product of the collaboration of a network of brain regions, instead of considering only few brain areas to be involved in that.

CONCLUSION

This study has important clinical applications, and extends our knowledge on the neuroanatomy of the language function.

Negative Prospective Memory in Alzheimer's Disease: "Do Not Perform That Action"

Relatively to "standard" prospective memory, i.e., remembering to perform a future action, little is known about negative prospective memory, i.e., remembering not to perform a future action. This study investigated the latter ability in Alzheimer's disease (AD). AD participants and healthy older adults were asked to click on the keyboard or not to click on it when a cue word was encountered. Results showed more omissions (i.e., forgetting to click the keyboard when the instruction was to do so) in AD participants than in healthy older adults, suggesting a prospective memory deficit. Interestingly, more commissions (i.e., clicking the keyboard when the instruction was not to do so) were also observed in AD participants than in healthy older adults. Similar levels of commissions and omissions were observed in AD participants and in healthy older adults. Also, commissions and omissions were correlated with performance on an inhibition assessment task. Our findings reveal that AD is characterized by not only difficulty in the retrieval of recent information, but also difficulty to inhibit no-longer appropriate stimulus-response associations previously learned, suggesting a specific deficit of negative prospective memory in AD.

In vivo magnetic resonance images reveal neuroanatomical sex differences through the application of voxel-based morphometry in C57BL/6 mice

Behaviorally relevant sex differences are often associated with structural differences in the brain and many diseases are sexually dimorphic in prevalence and progression. Characterizing sex differences is imperative to gaining a complete understanding of behavior and disease which will, in turn, allow for a balanced approach to scientific research and the development of therapies. In this study, we generated novel tissue probability maps (TPMs) based on 30 male and 30 female in vivo C57BL/6 mouse brain magnetic resonance images and used voxel-based morphometry (VBM) to analyze sex differences. Females displayed larger anterior hippocampus, basolateral amygdala, and lateral cerebellar cortex volumes, while males exhibited larger cerebral cortex, medial amygdala, and medial cerebellar cortex volumes. Atlas-based morphometry (ABM) revealed a statistically significant sex difference in cortical volume and no difference in whole cerebellar volume. This validated our VBM findings that showed a larger cerebral cortex in male mice and a pattern of dimorphism in the cerebellum where the lateral portion was larger in females and the medial portion was larger in males. These results are consonant with previous ex vivo studies examining sex differences, but also suggest further regions of interest.