Selective sex differences in declarative memory

The influence of hippocampal dopamine D2 receptor losses on episodic-memory decline across 5 years is moderated by BDNF and KIBRA polymorphisms

Losses in dopamine (DA) functioning may contribute to aging-related decline in cognition. Hippocampal DA is necessary for successful episodic memory formation. Previously, we reported that higher DA D2 receptor (D2DR) availability in hippocampus is beneficial for episodic memory only in older carriers of more advantageous genotypes of well-established plasticity-related genetic variations, the brain-derived neurotrophic factor (BDNF, rs6265) and the kidney and brain expressed protein (KIBRA, rs17070145) polymorphisms. Extending our observations to the longitudinal level, the current data show that individuals with one or no beneficial BDNF and KIBRA genotype (n = 80) decline more in episodic memory across five years, without any contribution of losses in hippocampal D2DR availability to memory decline. Although carriers of two beneficial genotypes (n = 39) did not decline overall in episodic memory, losses of hippocampal D2DR availability were predictive of episodic-memory decline among these individuals. Our findings have implications for interventions targeting DA modulation to enhance episodic memory in aging, which may not benefit all older individuals.

A cross-sectional study of the major risk factor at different levels of cognitive performance within Chinese-origin middle-aged and elderly individuals

OBJECTIVE

Senior citizens suffering from cognitive impairment (CI) are on the East Asia rise. Multiple variables could lead to inter-/intra-individual cognition effectiveness variations, though previous research efforts did not consider weighting issues.

METHODS

This study scrutinized 5639 participants meeting required inclusion criteria by the CHARLS. Cognitive capacity was evaluated through Mini-Mental State Examination (MMSE). Considering that MMSE scorings were not following normal distribution, a non-parametric test and multiple linear regression were performed to screen candidate variables linked to cognitive capacity. Such applicability of candidate factors in the cumulative effect and the weighting of the impact on cognitive performance were evaluated by random forest (RF) algorithm.

RESULTS

Age, gender, education, marital status, residence, the type of residence, exercise, socialization level and drinking were correlated to MMSE scorings (p < 0.05). Among them, age, education, gender and sociality were correlated to individual MMSE items (p < 0.05). Regardless of MMSE scores and several MMSE items, age is always a prime factor. However, in the attention and computation item, education is better than age and ranks first.

CONCLUSIONS

This preliminary study prompted age, education, gender, and sociality with varying weightings to be linked to cognitive capacity within a Chinese cohort by differing cognitive aspects. At different levels of cognitive performance, the main risk factors are basically similar, but there are still some differences.

Sex-specific variations in spatial reference memory acquisition: Insights from a comprehensive behavioral test battery in C57BL/6JRj mice

Sex differences in declarative memory are described in humans, revealing a female or a male advantage depending on the task. Specifically, spatial memory (i.e., spatial navigation) is typically most efficient in men. This sexual dimorphism has been replicated in male rats but not clearly in mice. In this study, sex differences in spatial memory were assessed in thirty-six C57BL/6 J mice (Janvier Labs; i.e., C57BL/6JRj mice), a widely used mouse substrain. Both male and female mice (12 weeks-old) were subjected to standard behavioral paradigms: the elevated plus maze, the open field test, the novel object and place tests, the forced swimming test, and the water maze test for spatial navigation. Across assessment, no sex differences were found in measures of locomotor activity, emotional and behavioral responses, and object and place recognition memories. In the water maze, male mice were faster in learning the platform location in the reference memory training and used more spatial strategies during the first training days. However, both sexes reached a similar asymptotic performance and performed similarly in the probe trial for long-term memory consolidation. No sex differences were found in the cued training, platform inversion sessions, or spatial working memory sessions. Hippocampal expression of the brain-derived neurotrophic factor was similar in both sexes, either in basal conditions or after performing the behavioral training battery. Importantly, female mice were not more variable than males in any measure analyzed. This outcome encourages the investigation of sex differences in animal models and the usefulness of including female mice in behavioral research.

Writing about a stressful experience improves semantic clustering of memory in men, not women

Writing about negative experiences can produce multiple benefits, including improvements in mental and emotional health. However, writing about negative experiences potentially be detrimental, as reliving and reexperiencing a negative memory can be painful. Although the emotional effects of writing about negative experiences are well established, the cognitive effects are less heavily explored, and no work to date has examined how writing about a stressful experience might influence episodic memory. We addressed this issue in the present study (N = 520) by having participants encode a list of 16 words that were organised around four semantic clusters, randomly assigning participants to write about an unresolved stressful experience (n = 263) or the events of the previous day (n = 257), and assessing their memory in a free recall task. Writing about a stressful experience did not influence overall memory performance; however, the stressful writing manipulation increased semantic clustering of information within memory for men, whereas the stressful writing manipulation did not influence semantic clustering of information within memory in women. Additionally, writing with more positive sentiment improved semantic clustering and reduced serial recall. These results provide evidence for unique sex differences in writing about stressful experiences and the role of sentiment in the effects of expressive writing.

Determinants of semantic and episodic memory decline among older adults in Ghana: Evidence from the WHO study on global AGEing and adult health Ghana wave 2

Objective

Determined factors associated with semantic (SM) and episodic memory (EM) among older adults aged 50 years and older in Ghana.

Methods

Data from WHO Study on Global AGEing and Adult Health (SAGE) Ghana Wave 2 was used for this study. Semantic memory (SM) and Episodic memory (EM) were the main study outcomes separately. The study employed Nested Ordinary Least Square regression analysis by sequentially adding 6 blocks of variables and comparison tests between the nested models.

Results

The study involved 3575 adult Ghanaians aged 50 years and older with a mean ± standard deviation of 62.6 ± 18.4 years. The overall mean ± SD of EM and SM were 5.86 ± 2.51 and 11.69 ± 8.59 respectively. Overall, analysis from block 6 showed a significant variation in SM by approximately 16.9%(ΔR2 = 1.17%) where increasing age, never married (β = -1.55; 95% CI = -2.41-0.69), being resident in Greater Accra (regional disparity) (β = -3.45; 95% CI = -4.73-2.20), underweight (β = -0.81;95% CI = -1.34-0.27), and moderate self-rated health (SRH) (β = -0.98; 95% CI = -1.52-0.45) significantly decreased SM. Similarly, increasing age, separated/divorced (β = -0.22; 95% CI = -0.35-0.87), being resident in Greater Accra (β = -0.53; 95% CI = -0.80-0.26), and moderate SRH (β = -0.20; 95% CI = -0.36--0.04) significantly decrease EM with an overall significant variation of approximately 22.9%(ΔR2 = 2.7%).

Conclusions

Increasing age, sex, marital status, regional disparity, and poor SRH significantly decreased both Semantic memory and Episodic memory. Higher educational attainment and life satisfaction significantly influenced SM and EM. These provide pointers to important socio-demographic determinants of SM and EM with implications for the implementation of the Ghana national ageing policy 2010, 'ageing with security and dignity', and as a key consideration for healthy ageing towards 2030.

Gender differences in the serial position among older adults

INTRODUCTION

There are gender disparities in age of diagnosis with Mild Cognitive Impairment (MCI) or dementia, which may be related to general female advantages in verbal memory across aging. Further examination of the serial position effect (SPE) may provide an avenue for earlier diagnosis of MCI/dementia among women.

METHOD

338 cognitively healthy adults aged 50⁺ (110 men; 228 women) were administered the Repeatable Battery for the Assessment of Neuropsychological Status (RBANS) List Learning task as part of dementia screening. We examined whether the SPE could be demonstrated on Trial 1 and delayed recall, and whether SPE patterns were consistent across genders, using mixed measure ANOVAs. Using regression, we also examined whether gender, SPE components, or their interactions predicted RBANS Delayed Memory Index (DMI) performance. Using cluster analyses, we identified a group with reduced primacy relative to recency on Trial 1 and a group without. We used ANOVA to examine whether clusters differed in DMI scores and whether this was moderated by gender.

RESULTS

We demonstrated the prototypical SPE on Trial 1. On delayed recall, we found reduced recency compared to primacy and middle performance. As expected, men exhibited worse performance on the DMI. However, gender did not interact with SPE. Primacy and middle, but not recency, performance on Trial 1 predicted DMI scores, as did the recency ratio. These relationships were not moderated by gender. Finally, participants with better primacy than recency on Trial 1 (N = 187) exhibited higher performance on DMI than participants with better recency than primacy (N = 151). Gender did not interact with cluster membership.

CONCLUSION

Our results have important clinical implications in assessment, where focusing on Trial 1 primacy performance and loss of recency between Trial 1 and delayed recall may help to address gender-related delays in age of diagnosis of MCI or dementia.

Sex differences in item and associative memory among older adults with amnestic mild cognitive impairment

In older adults without cognitive impairment, women have an advantage over men in verbal memory tests; however, whether women with amnestic mild cognitive impairment (aMCI) exhibit this advantage remains controversial. We evaluated sex-specific differences in older adults with and without aMCI in item and associative verbal memory by using an associative memory task with immediate and delayed recognition conditions. The associations between memory task performances and medial temporal morphometric measures were examined. The study included 49 individuals with aMCI and 55 healthy older adults (HOs). The results revealed that a female advantage in immediate item and delayed associative memory was evident in HOs, and the female advantage in associative memory persisted even after item memory performance was controlled. By contrast, the female advantage was absent in individuals with aMCI; such women had more associative false alarms than men with aMCI. Furthermore, decreases in item memory, associative memory, and cortical thickness in the perirhinal and entorhinal regions in individuals with aMCI versus their sex-matched controls were more prominent in women than in men. The relation between brain structure and associative memory function was evident only for women, indicating that women and men may have different cognitive and neural mechanisms for processing associative memory. These findings support the concept of cognitive reserve in women during normal aging. Accounting for sex differences in verbal memory performance is crucial to improve aMCI identification, particularly for women.

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.

Age, Sex, and Inhibitory Control: Identifying A Specific Impairment in Memorial, But Not Perceptual Inhibition in Older Women

Objectives

Declines in the ability to inhibit information, and the consequences to memory of unsuccessful inhibition, have been frequently reported to increase with age. However, few studies have investigated whether sex moderates such effects. Here, we examined whether inhibitory ability may vary as a function of age and sex, and the interaction between these two factors.

Method

202 older (mean age = 69.40 years) and younger (mean age =30.59 years) participants who had equivalent educational attainment and self-reported health completed 2 tasks that varied only in the time point at which inhibition should occur: either prior to, or after, encoding.

Results

While we did not find evidence for age or sex differences in inhibitory processes when information needed to be inhibited prior to encoding, when encoded information being actively held in working memory needed to be suppressed, we found that older women were particularly impaired relative to both younger women and men of either age group.

Discussion

These results provide further support for the presence of memorial inhibitory deficits in older age, but add nuance by implicating biological sex as an important mediator in this relationship, with it more difficult for older women to inhibit what was once relevant in memory.

Differential Age Trajectories of White Matter Changes Between Sexes Correlate with Cognitive Performances

Background: Aging is accompanied by a gradual deterioration in multiple cognitive abilities and brain structures. Both cognitive function and white matter (WM) structure are found to be associated with neurodegeneration diseases and correlated with sex during aging. However, it is still unclear whether the brain structural change could be attributable to sex, and how sex would affect cognitive performances during aging. Materials and Methods: Diffusion magnetic resonance imaging (MRI) scans were performed on 1127 healthy participants (age range: 21-89) at a single site. The age trajectories of the WM tract microstructure were delineated to estimate the turning age and changing rate between sexes. The canonical correlation analysis and moderated mediation analysis were used to examine the relationship between sex-linked WM tracts and cognitive performances. Results: The axon intactness and demyelination of sex-linked tracts during aging were multifaceted. Sex-linked tracts in females peak around 5 years later than those in males but change significantly faster after the turning age. Projection and association tracts (e.g., corticospinal tracts and parahippocampal cingulum) contributed to a significant decrease in visuospatial functions (VS) and executive functions (E). We discovered that there is a stronger indirect effect of sex-linked tracts on cognitive functions in females than in males. Conclusion: Our findings suggest that the vulnerable projection and association tracts in females may induce negative impacts on integrating multiple functions, which results in a faster decrease in VS and E.

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.

The cross-sectional association between mean corpuscular volume level and cognitive function in Chinese over 45 years old: Evidence from the China Health and Retirement Longitudinal Study

Fewer studies have focused on the independent association between mean corpuscular volume (MCV) and cognitive performance. This study was designed to characterize the cross-sectional association between MCV and cognitive performance in a large sample of Chinese residents (age≥45 years) from the China Health and Retirement Longitudinal Study (CHARLS). A total of 4023 male and 4173 female adults with MCV ≥ 80 fl were included for analysis. By multivariable linear regression analysis, for the total subjects, MCV level was significantly negatively associated with global cognitive function and episodic memory. When adjusted by sex, only in male subjects, higher MCV level was associated with reduced scores for global cognitive function, episodic memory and mental status. Via binary logistic regression analysis, the higher MCV level (MCV>100 fl) was associated with poor global cognitive function (OR = 1.601; 95% CI = 1.198–2.139; p = 0.001), episodic memory (OR = 1.679; 95% CI = 1.281–2.201; p<0.001), and mental status (OR = 1.422; 95% CI = 1.032–1.959; p = 0.031) for the whole participants. When testing this association by sex, the significant relationship between higher MCV level with worse episodic memory was observed both in male (OR = 1.690; 95% CI = 1.211–2.358; p = 0.002) and female (OR = 1.729; 95% CI = 1.079–2.770; p = 0.023) subjects; while the association between higher MCV level and poor global cognitive function (OR = 1.885; 95% CI = 1.329, 2.675; p<0.001) and mental status (OR = 1.544; 95% CI = 1.034, 2.306; p = 0.034) only existed in male subjects. Further studies are warranted to clarify the association between MCV level and cognitive performance by considering sex into consideration both cross-sectionally and longitudinally.

Biological and environmental predictors of heterogeneity in neurocognitive ageing: Evidence from Betula and other longitudinal studies

Individual differences in cognitive performance increase with advancing age, reflecting marked cognitive changes in some individuals along with little or no change in others. Genetic and lifestyle factors are assumed to influence cognitive performance in ageing by affecting the magnitude and extent of age-related brain changes (i.e., brain maintenance or atrophy), as well as the ability to recruit compensatory processes. The purpose of this review is to present findings from the Betula study and other longitudinal studies, with a focus on clarifying the role of key biological and environmental factors assumed to underlie individual differences in brain and cognitive ageing. We discuss the vital importance of sampling, analytic methods, consideration of non-ignorable dropout, and related issues for valid conclusions on factors that influence healthy neurocognitive ageing.

Can sex influence the neurocognition of language? Evidence from Parkinson's disease

Parkinson's disease (PD), which involves basal ganglia degeneration, affects language as well as motor function. However, which aspects of language are impaired in PD and under what circumstances remains unclear. We examined whether lexical and grammatical aspects of language are differentially affected in PD, and whether this dissociation is moderated by sex as well as the degree of basal ganglia degeneration. Our predictions were based on the declarative/procedural model of language. The model posits that grammatical composition, including in regular inflection, depends importantly on left basal ganglia procedural memory circuits, whereas irregular and other lexicalized forms are memorized in declarative memory. Since females tend to show declarative memory advantages as compared to males, the model further posits that females should tend to rely on this system for regulars, which can be stored as lexicalized chunks. We tested non-demented male and female PD patients and healthy control participants on the intensively studied paradigm of English regular and irregular past-tense production. Mixed-effects regression revealed PD deficits only at regular inflection, only in male patients. The degree of left basal ganglia degeneration, as reflected by right-side hypokinesia, predicted only regular inflection, and only in male patients. Left-side hypokinesia did not show this pattern. Past-tense frequency effects suggested that the female patients retrieved regular as well as irregular past-tense forms from declarative memory, whereas the males retrieved only irregulars. Sensitivity analyses showed that the pattern of findings was robust. The results, which are consistent with the declarative/procedural model, suggest a grammatical deficit in PD due to left basal ganglia degeneration, with a relative sparing of lexical retrieval. Female patients appear to compensate for this deficit by relying on chunks stored in declarative memory. More generally, the study elucidates the neurocognition of inflectional morphology and provides evidence that sex can influence how language is computed in the mind and brain.

Gender identity better than sex explains individual differences in episodic and semantic components of autobiographical memory: An fMRI study

Advances in the literature of sex-related differences in autobiographical memory increasingly tend to highlight the importance of psychosocial factors such as gender identity, which may explain these differences better than sex as a biological factor. To date, however, none of these behavioral studies have investigated this hypothesis using neuroimaging. The purpose of this fMRI study is to examine for the first time sex and gender identity-related differences in episodic and semantic autobiographical memory in healthy participants (M=19, W=18). No sex-related differences were found; however, sex-related effects of masculine and feminine gender identity were identified in men and women independently. These results confirm the hypothesis that differences in episodic and semantic autobiographical memory are best explained by gender but are an interaction between biological sex and gender identity and extend these findings to the field of neuroimaging. We discuss the importance of hormonal factors to be taken into consideration in the future.

Distinct Effects of Acute Aerobic Exercise on Declarative Memory and Procedural Memory Formation

Objective: To investigate the different effects of acute aerobic exercise on the formation of long-term declarative memory (DM) and procedural memory (PM). Methods: Twenty-two young men completed DM and PM tasks under three experimental conditions: pre-acquisition exercise, post-acquisition exercise, and no exercise (control). The DM task encompassed word learning, free recall tests both immediately and 1 h later, and a recognition test conducted 24 h after word learning. A serial reaction time task (SRTT) was utilized to assess exercise effects on PM. The SRTT included a sequence learning phase followed by sequence tests 1 h and 24 h later. The exercise program consisted of 30 min of moderate-intensity aerobic exercise. Results: In the DM task, compared to the control condition, pre-acquisition exercise, but not post-acquisition exercise, enhanced free recall performance significantly 1 h and 24 h later. The target word recognition rate and discriminative index (d') of the recognition test were significantly enhanced in both exercise conditions compared to the control condition. In the PM task, we observed significantly reduced (improved) reaction times at the 24-h test in the post-acquisition exercise condition compared to in the control condition. Conclusion: Acute aerobic exercise may enhance long-term DM and PM via effects on different processing periods. For DM, exercise had a pronounced effect during the encoding period, whereas for PM, exercise was found to have an enhancing effect during the consolidation period.

Testing the efficacy of a brief exercise intervention for enhancing exposure therapy outcomes

Recently, it has been hypothesized that a brief bout of exercise could cognitively enhance extinction learning processes theorized to underlie exposure therapy for pathological anxiety. The present study tested the exercise enhancement hypothesis in a sample of speech-anxious undergraduates (n = 84). During the first laboratory session, participants engaged in either 30 min of moderate-intensity exercise on a cycling ergometer (n = 37) or seated rest (n = 47) immediately following a brief speech exposure trial. They returned approximately one week later to give a follow-up speech. Contrary to expectation, there were no significant between-group differences in memory of a brief word list across four recall trials, which served as a manipulation check. Further, all main effects and interactions involving condition were nonsignificant. Post hoc tests revealed that participants who reported higher average perceived exertion during exercise demonstrated increases in an average anxiety composite across speeches relative to those who reported lower average perceived exertion, indicating that trying hard during the intervention predicted worse exposure trial outcomes. The implications of these findings, as well as future directions for this line of research, are explored.

Sex Differences in Work-Stress Memory Bias and Stress Hormones

Mental health problems related to chronic stress in workers appear to be sex-specific. Psychosocial factors related to work-life balance partly explain these sex differences. In addition, physiological markers of stress can provide critical information on the mechanisms explaining how chronic stress gets "under the skull" to increase vulnerability to mental health disorders in working men and women. Stress hormones access the brain and modulate attentional and memory process in favor of threatening information. In the present study, we tested whether male and female workers present a memory bias towards work-stress related information, and whether this bias is associated with concentrations of stress hormones in reactivity to a laboratory stressor (reactive levels) and samples taken in participants' workday (diurnal levels). In total, 201 participants (144 women) aged between 18 and 72 years underwent immediate and delayed recall tasks with a 24-word list, split as a function of valence (work-stress, positive, neutral). Participants were exposed to a psychosocial stressor in between recalls. Reactivity to stress was measured with saliva samples before and after the stressor. Diurnal cortisol was also measured with five saliva samples a day, during 2 workdays. Our exploratory results showed that men presented greater cortisol reactivity to stress than women, while women recalled more positive and neutral words than men. No sex difference was detected on the recall of work-stress words, before or after exposure to stress. These results do not support the hypothesis of a sex-specific cognitive bias as an explanatory factor for sex differences in stress-related mental health disorders in healthy male and female workers. However, it is possible that such a work-stress bias is present in individuals who have developed a mental-health disorder related to workplace stress or who have had one in the recent past. Consequently, future studies could use our stress memory bias task to assess this and other hypotheses in diverse working populations.

Early-life education may help bolster declarative memory in old age, especially for women

Although declarative memory declines with age, sex and education might moderate these weaknesses. We investigated effects of sex and education on nonverbal declarative (recognition) memory in 704 older adults (aged 58-98, 0-17 years of education). Items were drawings of real and made-up objects. Age negatively impacted declarative memory, though this age effect was moderated by sex and object-type: it was steeper for males than females, but only for real objects. Education was positively associated with memory, but also interacted with sex and object-type: education benefited women more than men (countering the age effects, especially for women), and remembering real more than made-up objects. The findings suggest that nonverbal memory in older adults is associated negatively with age but positively with education; both effects are modulated by sex, and by whether learning relates to preexisting or new information. The study suggests downstream benefits from education, especially for girls.

Sex Differences in Functional Brain Networks for Language

Men and women process language differently, but how the brain functions to support this difference is poorly understood. A few studies reported sex influences on brain activation for language, whereas others failed to detect the difference at the functional level. Recent advances of brain network analysis have shown great promise in picking up brain connectivity differences between sexes, leading us to hypothesize that the functional connections among distinct brain regions for language may differ in males and females. To test this hypothesis, we scanned 58 participants’ brain activities (28 males and 30 females) in a semantic decision task using functional magnetic resonance imaging. We found marked sex differences in dynamic interactions among language regions, as well as in functional segregation and integration of brain networks during language processing. The brain network differences were further supported by a machine learning analysis that accurately discriminated males from females using the multivariate patterns of functional connectivity. The sex-specific functional brain connectivity may constitute an essential neural basis for the long-held notion that men and women process language in different ways. Our finding also provides important implications for sex differences in the prevalence of language disorders, such as dyslexia and stuttering.

The brief assessment of cognition in affective disorders: Normative data for the Italian population

BACKGROUND

To date there are no validated tests in Italian to assess cognitive functions in Bipolar Disorder. Therefore, this study aimed to provide normative data for the Italian version of the Brief Assessment of Cognition in Affective Disorders (BAC-A), a battery targeting neuro- and affective-cognition in affective disorders.

METHODS

Data were collected from 228 healthy participants (age range: 18-67; mean age: 34.68 ± 12.15 years) across eight recruiting sites. The influence of age, sex and education was measured and adjusted for using multivariate stepwise regression models. Normative values were established by means of the Equivalent Score approach.

RESULTS

Most of the BAC-A subtests showed patterns of association with age (inversely associated with overall cognitive performance), education (positively associated with Verbal Memory and Fluency, Digit Sequencing and Affective Processing subtests) and sex (females performed better than males in the Affective Interference Test but worse in the Emotion Inhibition Task, Digit Sequencing and Tower of London).

LIMITATIONS

The sample size was not sufficiently large for developing stratified norms, using 10-years ranges. Moreover, the participants included in the study were, on average, highly educated.

CONCLUSIONS

The normative data of the BAC-A provided in this study can serve as a cognitive functioning reference for Italian-speaking participants within the age range of the study sample. This can increase the applicability of this test in both clinical and research settings. The reliability and validity of the Italian BAC-A need to be further investigated.

The effects of acute exercise on episodic memory function among young university students: moderation considerations by biological sex

Background: The objective of this study was to evaluate potential sex-specific differences on episodic memory function and determine whether sex moderates the effects of acute exercise on episodic memory.

Methods: A randomized controlled intervention was employed. This experiment was conducted among young University students (mean age = 21 years). Both males (n=20) and females (n=20)completed two counterbalanced laboratory visits, with one visit involving a 15-minute bout of moderate-intensity exercise prior to the memory task. The control visit engaged in a time matched seated task. Memory function (including short-term memory, learning, and long-term memory) was assessed from the RAVLT (Rey Auditory Verbal Learning Test).

Results: We observed a significant main effect for time (P<0.001, ƞ²_p= 0.77) and a marginally significant main effect for sex (P=0.06, ƞ²_p= 0.09), but no time by sex by condition interaction(P=0.91, ƞ²_p= 0.01). We also observed some suggestive evidence of a more beneficial effect of acute exercise on memory for females.

Conclusion: In conclusion, females outperformed males in verbal memory function. Additional research is needed to further evaluate whether sex moderates the effects of acute exercise on memory function.

The Influence of Hippocampal Dopamine D2 Receptors on Episodic Memory Is Modulated by BDNF and KIBRA Polymorphisms

Episodic memory is a polygenic trait influenced by different molecular mechanisms. We used PET and a candidate gene approach to investigate how individual differences at the molecular level translate into between-person differences in episodic memory performance of elderly persons. Specifically, we examined the interactive effects between hippocampal dopamine D2 receptor (D2DR) availability and candidate genes relevant for hippocampus-related memory functioning. We show that the positive effects of high D2DR availability in the hippocampus on episodic memory are confined to carriers of advantageous genotypes of the brain-derived neurotrophic factor (BDNF, rs6265) and the kidney and brain expressed protein (KIBRA, rs17070145) polymorphisms. By contrast, these polymorphisms did not modulate the positive relationship between caudate D2DR availability and episodic memory.

Modulation of striatum based non-declarative and medial temporal lobe based declarative memory predicts academic achievement at university level

BACKGROUND

There is a dearth of research on the roles of non-declarative (implicit) learning linked to the striatum and declarative (explicit) learning associated with the medial temporal lobes as predictors of academic attainment.

METHODS

Participants were 120 undergraduate students, studying Psychology or Engineering, who completed several long-term memory tests.

RESULTS

There was a significant interaction between the groups (Psychology or Engineering) and task type (declarative or non-declarative): Engineers performed better at declarative and psychologists at non-declarative learning. Furthermore, non-declarative but not declarative learning scores were significant correlates of academic achievement (r = 0.326, p < .05). Moreover, competitive modulation (activation of non-declarative learning in conjunction with deactivation of declarative learning) was a significant predictor of future academic achievement in both psychology (r = 0.264, p < .05) and Engineering (r = 0.300, p < .05) groups.

CONCLUSIONS

The results confirm that these declarative and non-declarative systems interact competitively and that the extent of this competition may have implications for understanding educational attainment.

The Role of Sex in Memory Function: Considerations and Recommendations in the Context of Exercise

There is evidence to suggest that biological sex plays a critical role in memory function, with sex differentially influencing memory type. In this review, we detail the current evidence evaluating sex-specific effects on various memory types. We also discuss potential mechanisms that explain these sex-specific effects, which include sex differences in neuroanatomy, neurochemical differences, biological differences, and cognitive and affect-related differences. Central to this review, we also highlight that, despite the established sex differences in memory, there is little work directly comparing whether males and females have a differential exercise-induced effect on memory function. As discussed herein, such a differential effect is plausible given the clear sex-specific effects on memory, exercise response, and molecular mediators of memory. We emphasize that future work should be carefully powered to detect sex differences. Future research should also examine these potential exercise-related sex-specific effects for various memory types and exercise intensities and modalities. This will help enhance our understanding of whether sex indeed moderates the effects of exercise and memory function, and as such, will improve our understanding of whether sex-specific, memory-enhancing interventions should be developed, implemented, and evaluated.

Gender differences of neuropsychological profiles in cognitively normal older people without amyloid pathology

OBJECTIVE

To investigate the impact of sex on cognition among cognitively normal older people without amyloid pathology.

METHODS

The study sample consisted of 83 males (mean age 74years, ranging from 65 to 88years) and 111 females (mean age 72years, ranging from 65 to 89years) who were cognitively normal without amyloid pathology confirmed by Pittsburgh compound B PET scan. We examined the sex discrepancies in cognition using a comprehensive neuropsychological battery.

RESULTS

Our data showed significantly greater advantage for women than men on the tasks of verbal memory and category fluency while better performance of naming in men than women when age, education and depressive symptoms were considered.

CONCLUSION

These findings highlight the importance of considering sex differences in the interpretation of cognitive data which contribute to clinical diagnosis of neurodegenerative disorders, such as Alzheimer's disease.

Different Context but Similar Cognitive Structures: Older Adults in Rural Bangladesh

Most research in cognitive aging is based on literate participants from high-income and Western populations. The extent to which findings generalize to low-income and illiterate populations is unknown. The main aim was to examine the structure of between-person differences in cognitive functions among elderly from rural Bangladesh. We used data from the Poverty and Health in Aging (PHA) project in Bangladesh. The participants (n = 452) were in the age range 60-92 years. Structural equation modeling was used to estimate the fit of a five-factor model (episodic recall, episodic recognition, verbal fluency, semantic knowledge, processing speed) and to examine whether the model generalized across age, sex, and literacy. This study demonstrates that an established model of cognition is valid also among older persons from rural Bangladesh. The model demonstrated strong (or scalar) invariance for age, and partial strong invariance for sex and literacy. Semantic knowledge and processing speed showed weak (or metric) sex invariance, and semantic knowledge demonstrated also sensitivity to illiteracy. In general, women performed poorer on all abilities. The structure of individual cognitive differences established in Western populations also fits a population in rural Bangladesh well. This is an important prerequisite for comparisons of cognitive functioning (e.g., declarative memory) across cultures. It is also worth noting that absolute sex differences in cognitive performance among rural elderly in Bangladesh differ from those usually found in Western samples.

Sex differences in verbal and nonverbal learning before and after temporal lobe epilepsy surgery

Women outperform men in a host of episodic memory tasks, yet the neuroanatomical basis for this effect is unclear. It has been suggested that the anterior temporal lobe might be especially relevant for sex differences in memory. In the current study, we investigated whether temporal lobe epilepsy (TLE) has an influence on sex effects in learning and memory and whether women and men with TLE differ in their risk for memory deficits after epilepsy surgery. 177 patients (53 women and 41 men with left TLE, 42 women and 41 men with right TLE) were neuropsychologically tested before and one year after temporal lobe resection. We found that women with TLE had better verbal, but not figural, memory than men with TLE. The female advantage in verbal memory was not affected by temporal lobe resection. The same pattern of results was found in a more homogeneous subsample of 84 patients with only hippocampal sclerosis who were seizure-free after surgery. Our findings challenge the concept that the anterior temporal lobe plays a central role in the verbal memory advantage for women.

Dopamine Receptor Genes Modulate Associative Memory in Old Age

Previous research shows that associative memory declines more than item memory in aging. Although the underlying mechanisms of this selective impairment remain poorly understood, animal and human data suggest that dopaminergic modulation may be particularly relevant for associative binding. We investigated the influence of dopamine (DA) receptor genes on item and associative memory in a population-based sample of older adults (n = 525, aged 60 years), assessed with a face-scene item associative memory task. The effects of single-nucleotide polymorphisms of DA D1 (DRD1; rs4532), D2 (DRD2/ANKK1/Taq1A; rs1800497), and D3 (DRD3/Ser9Gly; rs6280) receptor genes were examined and combined into a single genetic score. Individuals carrying more beneficial alleles, presumably associated with higher DA receptor efficacy (DRD1 C allele; DRD2 A2 allele; DRD3 T allele), performed better on associative memory than persons with less beneficial genotypes. There were no effects of these genes on item memory or other cognitive measures, such as working memory, executive functioning, fluency, and perceptual speed, indicating a selective association between DA genes and associative memory. By contrast, genetic risk for Alzheimer disease (AD) was associated with worse item and associative memory, indicating adverse effects of APOE ε4 and a genetic risk score for AD (PICALM, BIN1, CLU) on episodic memory in general. Taken together, our results suggest that DA may be particularly important for associative memory, whereas AD-related genetic variations may influence overall episodic memory in older adults without dementia.

Effect size for the main cognitive function determinants in a large cross-sectional study

BACKGROUND AND PURPOSE

The aim of our study was to examine the effect sizes of different cognitive function determinants in middle and early old age.

METHODS

Cognitive functions were assessed in 11 711 volunteers (45 to 75 years old), included in the French CONSTANCES cohort between January 2012 and May 2014, using the free and cued selective reminding test (FCSRT), verbal fluency tasks, digit-symbol substitution test (DSST) and trail making test (TMT), parts A and B. The effect sizes of socio-demographic (age, sex, education), lifestyle (alcohol, tobacco, physical activity), cardiovascular (diabetes, blood pressure) and psychological (depressive symptomatology) variables were computed as omega-squared coefficients (ω² ; part of the variation of a neuropsychological score that is independently explained by a given variable).

RESULTS

These sets of variables explained from R² = 10% (semantic fluency) to R² = 26% (DSST) of the total variance. In all tests, socio-demographic variables accounted for the greatest part of the explained variance. Age explained from ω² = 0.5% (semantic fluency) to ω² = 7.5% (DSST) of the total score variance, gender from ω² = 5.2% (FCSRT) to a negligible part (semantic fluency or TMT) and education from ω² = 7.2% (DSST) to ω² = 1.4% (TMT-A). Behavioral, cardiovascular and psychological variables only slightly influenced the cognitive test results (all ω² < 0.8%, most ω² < 0.1%).

CONCLUSION

Socio-demographic variables (age, gender and education) are the main variables associated with cognitive performance variations between 45 and 75 years of age in the general population.

Persistence of Gender Related-Effects on Visuo-Spatial and Verbal Working Memory in Right Brain-Damaged Patients

The aim of the present study was to verify if gender differences in verbal and visuo-spatial working memory would persist following right cerebral lesions. To pursue our aim we investigated a large sample (n. 346) of right brain-damaged patients and healthy participants (n. 272) for the presence of gender effects in performing Corsi and Digit Test. We also assessed a subgroup of patients (n. 109) for the nature (active vs. passive) of working memory tasks. We tested working memory (WM) administering the Corsi Test (CBT) and the Digit Span (DS) using two different versions: forward (fCBT and fDS), subjects were required to repeat stimuli in the same order that they were presented; and backward (bCBT and bDS), subjects were required to repeat stimuli in the opposite order of presentation. In this way, passive storage and active processing of working memory were assessed. Our results showed the persistence of gender-related effects in spite of the presence of right brain lesions. We found that men outperformed women both in CBT and DS, regardless of active and passive processing of verbal and visuo-spatial stimuli. The presence of visuo-spatial disorders (i.e., hemineglect) can affect the performance on Corsi Test. In our sample, men and women were equally affected by hemineglect, therefore it did not mask the gender effect. Generally speaking, the persistence of the men's superiority in visuo-spatial tasks may be interpreted as a protective factor, at least for men, within other life factors such as level of education or kind of profession before retirement.

Depressive Mood and Testosterone Related to Declarative Verbal Memory Decline in Middle-Aged Caregivers of Children with Eating Disorders

Caring for children diagnosed with a chronic psychological disorder such as an eating disorder (ED) can be used as a model of chronic stress. This kind of stress has been reported to have deleterious effects on caregivers’ cognition, particularly in verbal declarative memory of women caregivers. Moreover, high depressive mood and variations in testosterone (T) levels moderate this cognitive decline. The purpose of this study was to characterize whether caregivers of individuals with EDs (n = 27) show declarative memory impairments compared to non-caregivers caregivers (n = 27), using for this purpose a standardized memory test (Rey’s Auditory Verbal Learning Test). Its purpose was also to examine the role of depressive mood and T in memory decline. Results showed that ED caregivers presented high depressive mood, which was associated to worse verbal memory performance, especially in the case of women. In addition, all caregivers showed high T levels. Nonetheless, only in the case of women caregivers did T show a curvilinear relationship with verbal memory performance, meaning that the increases of T were associated to the improvement in verbal memory performance, but only up to a certain point, as after such point T continued to increase and memory performance decreased. Thus, chronic stress due to caregiving was associated to disturbances in mood and T levels, which in turn was associated to verbal memory decline. These findings should be taken into account in the implementation of intervention programs for helping ED caregivers cope with caregiving situations and to prevent the risk of a pronounced verbal memory decline.

Effects of sex and proficiency in second language processing as revealed by a large-scale fNIRS study of school-aged children

Previous neuroimaging studies in adults have revealed that first and second languages (L1/L2) share similar neural substrates, and that proficiency is a major determinant of the neural organization of L2 in the lexical-semantic and syntactic domains. However, little is known about neural substrates of children in the phonological domain, or about sex differences. Here, we conducted a large-scale study (n = 484) of school-aged children using functional near-infrared spectroscopy and a word repetition task, which requires a great extent of phonological processing. We investigated cortical activation during word processing, emphasizing sex differences, to clarify similarities and differences between L1 and L2, and proficiency-related differences during early L2 learning. L1 and L2 shared similar neural substrates with decreased activation in L2 compared to L1 in the posterior superior/middle temporal and angular/supramarginal gyri for both sexes. Significant sex differences were found in cortical activation within language areas during high-frequency word but not during low-frequency word processing. During high-frequency word processing, widely distributed areas including the angular/supramarginal gyri were activated in boys, while more restricted areas, excluding the angular/supramarginal gyri were activated in girls. Significant sex differences were also found in L2 proficiency-related activation: activation significantly increased with proficiency in boys, whereas no proficiency-related differences were found in girls. Importantly, cortical sex differences emerged with proficiency. Based on previous research, the present results indicate that sex differences are acquired or enlarged during language development through different cognitive strategies between sexes, possibly reflecting their different memory functions.

Geschlechtseffekte bei Intelligenz- und Gedächtnisleistungen

Diese Studie untersucht die Zusammenhänge von Intelligenz- und Gedächtnisleistungen in der Wechsler Adult Intelligence Scale-IV und der Wechsler Memory Scale-IV unter Berücksichtigung des Geschlechts (N = 137 Gesunde, 63 w/74 m). Ein Vorteil der weiblichen Testpersonen im verbalen episodischen Gedächtnis sowie in einzelnen Aufgaben zur Verarbeitungsgeschwindigkeit konnte beobachtet werden. Die männlichen Testpersonen schnitten in den Untertests Allgemeines Wissen und Visuelle Puzzles besser ab. Wie gut Gedächtnisleistungen Intelligenzleistungen erklären beziehungsweise vorhersagen, ist aufgrund unserer Ergebnisse nicht nur abhängig von den Aufgaben, sondern auch vom Geschlecht.

Gender Differences in Cognitive Performance in Old Age

Objective: To examine gender differences in level and change of cognitive performance in the oldest old while accounting for gender differences in longevity. Method: 574 individuals, aged 80 years and older, from the OCTO Twin Study. Five cognitive domains were administered at five occasions at 2-year intervals. Results: There were no cognitive differences between men and women, with the exception that men showed a steeper rate of decline in semantic memory. This effect was driven by men who had developed dementia and declined at a faster rate than women. Conclusion: Our results support previous findings showing minor to nonexisting gender differences in cognition among nondemented individuals in very old age when taking gender differences in longevity into account.

Gender Differences in Child Word Learning

In prior work with adults, women were found to outperform men on a paired-associates word-learning task, but only when learning phonologically-familiar novel words. The goal of the present work was to examine whether similar gender differences in word learning would be observed in children. In addition to manipulating phonological familiarity, referent familiarity was also manipulated. Children between the ages of 5 and 7 learned phonologically-familiar or phonologically-unfamiliar novel words in association with pictures of familiar referents (animals) or unfamiliar referents (aliens). Retention was tested via a forced-choice recognition measure administered immediately after the learning phase. Analyses of retention data revealed stronger phonological and referent familiarity effects in girls than in boys. Moreover, girls outperformed boys only when learning phonologically-familiar novel words and when learning novel words in association with familiar referents. These findings are interpreted to suggest that females are more likely than males to recruit native-language phonological and semantic knowledge during novel word learning.

Children's computation of complex linguistic forms: a study of frequency and imageability effects

This study investigates the storage vs. composition of inflected forms in typically-developing children. Children aged 8–12 were tested on the production of regular and irregular past-tense forms. Storage (vs. composition) was examined by probing for past-tense frequency effects and imageability effects – both of which are diagnostic tests for storage – while controlling for a number of confounding factors. We also examined sex as a factor. Irregular inflected forms, which must depend on stored representations, always showed evidence of storage (frequency and/or imageability effects), not only across all children, but also separately in both sexes. In contrast, for regular forms, which could be either stored or composed, only girls showed evidence of storage. This pattern is similar to that found in previously-acquired adult data from the same task, with the notable exception that development affects which factors influence the storage of regulars in females: imageability plays a larger role in girls, and frequency in women. Overall, the results suggest that irregular inflected forms are always stored (in children and adults, and in both sexes), whereas regulars can be either composed or stored, with their storage a function of various item- and subject-level factors.

Gender differences in episodic memory and visual working memory including the effects of age

Analysing the relationship between gender and memory, and examining the effects of age on the overall memory-related functioning, are the ongoing goals of psychological research. The present study examined gender and age group differences in episodic memory with respect to the type of task. In addition, these subgroup differences were also analysed in visual working memory. A sample of 366 women and 330 men, aged between 16 and 69 years of age, participated in the current study. Results indicate that women outperformed men on auditory memory tasks, whereas male adolescents and older male adults showed higher level performances on visual episodic and visual working memory measures. However, the size of gender-linked effects varied somewhat across age groups. Furthermore, results partly support a declining performance on episodic memory and visual working memory measures with increasing age. Although age-related losses in episodic memory could not be explained by a decreasing verbal and visuospatial ability with age, women's advantage in auditory episodic memory could be explained by their advantage in verbal ability. Men's higher level visual episodic memory performance was found to result from their advantage in visuospatial ability. Finally, possible methodological, biological, and cognitive explanations for the current findings are discussed.

The effects of gender on the retrieval of episodic and semantic components of autobiographical memory

Despite consistent evidence that women exhibit greater episodic memory specificity than men, little attention has been paid to gender differences in the production of episodic details during autobiographical recall under conditions of high and low retrieval support. Similarly the role of gender on the production of semantic details used to support autobiographical memory recollections of specific events has been largely unexplored. In the present study an undergraduate sample of 50 men and 50 women were assessed using the Autobiographical Interview (Levine, Svoboda, Hay, Winocur, & Moscovitch, 2002). Women recalled more episodic information compared to men in the high retrieval support condition, whereas no gender differences were found in the low retrieval support condition. In addition, women produced more repetitions compared to men in the high retrieval support condition. No gender differences were found in the production of semantic details. These results are interpreted in terms of gender differences in encoding and reminiscence practices. This research adds to the literature on gender differences in memory recall and suggests that gender is an important variable in explaining individual differences in AM recall.

Effects of acute exercise on long-term memory

In this study, we tested the effect of acute exercise on long-term memory, specifically the timing of exercise relative to the memory challenge. We assessed memory via paragraph recall, in which participants listened to two paragraphs (exposure) and recounted them following a 35-min delay. Participants (n = 48) were randomly assigned to one of three groups: exercise prior to exposure, exercise after exposure, or no-exercise. Exercise consisted of 30 min on a cycle ergometer including 20 min at moderate intensity. Only the exercise prior group recalled significantly more than the control group (p < .05). Differences among the exercise groups failed to reach significance (p = .09). Results indicated that acute exercise positively influenced recall and that exercise timing relative to memory task may have an impact on this effect.

Cohort differences in cognitive aging and terminal decline in the Seattle Longitudinal Study

Life span researchers have long been interested in how and why fundamental aspects of human ontogeny differ between cohorts of people who have lived through different historical epochs. When examined at the same age, later born cohorts are often cognitively and physically fitter than earlier born cohorts. Less is known, however, about cohort differences in the rate of cognitive aging and if, at the very end of life, pervasive mortality-related processes overshadow and minimize cohort differences. We used data on 5 primary mental abilities from the Seattle Longitudinal Study (Schaie, 2005) to compare both age-related and mortality-related changes between earlier born cohorts (1886-1913) and later born cohorts (1914-1948). Our models covary for several individual and cohort differences in central indicators of life expectancy, education, health, and gender. Age-related growth models corroborate and extend earlier findings by documenting level differences at age 70 of up to 0.50 SD and less steep rates of cognitive aging on all abilities between 50 and 80 years of age favoring the later born cohort. In contrast, mortality-related models provide limited support for positive cohort differences. The later born cohort showed steeper mortality-related declines. We discuss possible reasons why often reported positive secular trends in age-related processes may not generalize to the vulnerable segment of the population that is close to death and suggest routes for further inquiry.

Gender differences in adult word learning

In prior work, women were found to outperform men on short-term verbal memory tasks. The goal of the present work was to examine whether gender differences on short-term memory tasks are tied to the involvement of long-term memory in the learning process. In Experiment 1, men and women were compared on their ability to remember phonologically-familiar novel words and phonologically-unfamiliar novel words. Learning of phonologically-familiar novel words (but not of phonologically-unfamiliar novel words) can be supported by long-term phonological knowledge. Results revealed that women outperformed men on phonologically-familiar novel words, but not on phonologically-unfamiliar novel words. In Experiment 2, we replicated Experiment 1 using a within-subjects design, and confirmed gender differences on phonologically-familiar, but not on phonologically-unfamiliar stimuli. These findings are interpreted to suggest that women are more likely than men to recruit native-language phonological knowledge during novel word-learning.

Sex differences in unfamiliar face identification: evidence from matching tasks

Research on sex differences in face recognition has reported mixed results, on balance suggesting an advantage for female observers. However, it is not clear whether this advantage is specific to face processing or reflects a more general superiority effect in episodic memory. The current study therefore examined sex differences with a face-matching task that eliminates memory demands. Across two experiments, female but not male observers showed an own-sex advantage on match trials, in which two pictures have to be identified as the same person. This advantage was present for whole faces and when only the internal or external facial features were shown. Female observers were also more accurate in these three conditions on mismatch encounters, in which two photographs have to be identified as different people, but this reflects a more general effect that is present for male and female faces. These findings converge with claims of a female advantage in face recognition and demonstrate that this effect persists when memory demands are eliminated.

Quantifying human subjective experience and social interaction using the eXperience Induction Machine

With the advance of novel brain imaging technology more correlations between complex human properties and the neuronal substrate can be assessed. However, thus far, not many well-validated paradigms exist that would allow for a systematic and quantitative exploration of these phenomena. For instance, despite the rapid technological advances in the domain of mixed and virtual reality systems, a fundamental issue remains how we can define and quantify "presence". A standard approach has been to use questionnaires and self-report measures. However, it has been well established that humans' capabilities to access and externalize their internal states are limited. Hence, we have investigated the question whether other less subjective measures can be devised that can corroborate subjective self-reports on presence. In particular, we have developed a quantitative recollection task that assesses the ability of human subjects (N=40) to recollect the factual structure and organization of a structured and fully controlled experience in a human accessible mixed reality space, the eXperience Induction Machine (XIM). In this structured experience - referred to as the "Autodemo"--a virtual guide explains the key elements and properties of XIM while the user is able to freely move around in the space. To evaluate the users' experience and the amount of factual information retained about the Autodemo, we used the ITC-SOPI questionnaire and a recall test specifically designed for the Autodemo. We found significant correlations between spatial presence and engagement factors of ITC-SOPI and recall performance. Moreover we observed an interaction with the participants' gender. Our results show that we can assess correlates of "presence" by focusing on other dependent measures such as those related to memory and performance. Additionally, our work exemplifies how virtual and mixed reality systems provide new ways to address fundamental questions in psychology and cognitive neuroscience.

Successful physiological aging and episodic memory: a brain stimulation study

Functional neuroimaging studies have shown that younger adults tend to asymmetrically recruit specific regions of an hemisphere in an episodic memory task (Hemispheric Encoding Retrieval Asymmetry-HERA model). In older adults, this hemispheric asymmetry is generally reduced as suggested by the Hemispheric Asymmetry Reduction for OLDer Adults-HAROLD-model. Recent works suggest that while low-performing older adults do not show this reduced asymmetry, high-performing older adults counteract age-related neural decline through a plastic reorganization of cerebral networks that results in reduced functional asymmetry. However, the issue of whether high- and low-performing older adults show different degrees of asymmetry and the relevance of this process for counteracting aging have not been clarified. We used transcranial magnetic stimulation (TMS) to transiently interfere with the function of the dorsolateral prefrontal cortex (DLPFC) during encoding or retrieval of associated and non-associated word pairs. A group of healthy older adults was studied during encoding and retrieval of word pairs. The subjects were divided in two subgroups according to their experimental performance (i.e., high- and low-performing). TMS effects on retrieval differed according to the subject's subgroup. In particular, the predominance of left vs. right DLPFC effects during encoding, predicted by the HERA model, was observed only in low-performing older adults, while the asymmetry reduction predicted by the HAROLD model was selectively shown for the high-performing group. The present data confirm that older adults with higher memory performance show less prefrontal asymmetry as an efficient strategy to counteract age-related memory decline.

The influence of sex on the course and psychiatric correlates of ADHD from childhood to adolescence: a longitudinal study

BACKGROUND

Little is known about the influence of sex on the course of attention-deficit/hyperactivity disorder (ADHD) and its comorbid psychiatric conditions. The purpose of this study was to examine the effect of sex on the course and psychiatric correlates of ADHD from childhood into adolescence.

METHODS

Two identically designed, longitudinal, case-control family studies of male and female probands with and without ADHD and their siblings were combined. All subjects were blindly assessed with structured diagnostic interviews. Among subjects with a lifetime history of ADHD (n = 471, mean age 11.5 +/- 4.3 years at baseline), we used linear growth curve models to estimate the effect of time on the change in ADHD symptoms, and whether this effect differed by sex. We also we examined the effect of sex on the association between ADHD and the longitudinal progression of comorbid psychopathology using structural equation models.

RESULTS

We found no evidence that sex moderated the effect of age on ADHD symptoms; in both genders, age exhibited a similar effect on the decline of ADHD symptoms. However, the female sample demonstrated greater stability in comorbid psychopathology from childhood into adolescence. Furthermore, we found that the stability of comorbid psychopathology in females remained significant after accounting for the correlation between adolescent psychopathology and adolescent ADHD. In males, childhood and adolescent comorbid psychopathology were no longer correlated when adolescent ADHD was taken into account.

CONCLUSIONS

Our findings indicate that while the course of ADHD across childhood and adolescence did not differ between males and females, patterns of psychiatric comorbidity were conditional on sex. Future studies should explicitly test how sex modifies the associations between ADHD and risk factors and ADHD and associated functional outcomes.