Assessment of memory skills in illiterates: strategy differences or test artifact?

Previous studies have reported that illiterates perform more poorly than literates on a variety of neuropsychological measures. We investigated the hypothesis that putative memory deficits in illiterates are an artifact of the assessment tools used rather than a reflection of an 'underdeveloped' ability. In order to accomplish this, we designed two tests, a word list learning test and an object learning test. The illiterate group performed more poorly than semiliterate and literate groups on most variables of the word list learning test, but only on delayed recall and semantic clustering on the object learning test. Our findings suggest that poor memory performance among illiterates can be attributed both to the nature of the task, as well as to the use of different cognitive mechanisms to recall learned information. Presumably, formal education may enhance the innate ability of learning through training individuals in efficient learning and retrieval strategies. We emphasize the importance of developing and using ecologically valid neuropsychological tests to assess illiterate individuals.     

Age-related differences in memory and executive functions in healthy APOE ɛ4 carriers: the contribution of individual differences in prefrontal volumes and systolic blood pressure

Advanced age and vascular risk are associated with declines in the volumes of multiple brain regions, especially the prefrontal cortex, and the hippocampus. Older adults, even unencumbered by declining health, perform less well than their younger counterparts in multiple cognitive domains, such as episodic memory, executive functions, and speed of perceptual processing. Presence of a known genetic risk factor for cognitive decline and vascular disease, the ?4 allele of the apolipoprotein E (APOE) gene, accounts for some share of those declines; however, the extent of the joint contribution of genetic and physiological vascular risk factors on the aging brain and cognition is unclear. In a sample of healthy adults (age 19–77), we examined the effects of a vascular risk indicator (systolic blood pressure, SBP) and volumes of hippocampus (HC), lateral prefrontal cortex (lPFC), and prefrontal white matter (pFWM) on processing speed, working memory (WM), and recognition memory. Using path analyses, we modeled indirect effects of age, SBP, and brain volumes on processing speed, WM, and memory and compared the patterns of structural relations among those variables in APOE ?4 carriers and ?3 homozygotes. Among ?4 carriers, age differences in WM were explained by increase in SBP, reduced FWM volume, and slower processing. In contrast, lPFC and FWM volumes, but not BP, explained a share of age differences in WM among ?3 homozygotes. Thus, even in healthy older carriers of the APOE ?4 allele, clinically unremarkable increase in vascular risk may be associated with reduced frontal volumes and impaired cognitive functions.     

Components of recognition memory: dissociable cognitive processes or just differences in representational complexity?

Many current theoretical views within the literature on recognition memory-a representative sample of which is provided by the present special issue-advocate the dissociation of recognition memory into two cognitive processes: familiarity-based recognition, and recollection/recall. Furthermore, these processes are proposed to be mediated by distinct and dissociable anatomical regions, usually the perirhinal cortex and hippocampus, respectively. In this article, we describe a representational-hierarchical view that provides an account of cognition, including mnemonic and perceptual processing, within a brain pathway we term the ventral visual-perirhinal-hippocampal stream. According to this view cognition, perception, memory, and indeed amnesia may be understood by considering the content and organization of stimulus representations in the brain. Taking this view leads us to question the idea of cognitive modules for introspectively derived notions such as familiarity and recollection. We begin by reviewing the representational-hierarchical framework, explain how it has been used to account for object recognition memory in perirhinal cortex, and review the rationale for extending this framework to the hippocampus. We then discuss whether the principles of the representational-hierarchical framework can be used to understand recollection and familiarity in terms of stimulus complexity, and use these principles to reconsider some of the evidence for neuroanatomical, dual-process models of recognition memory.     

What comes first? Electrophysiological differences in the temporal course of memory and future thinking

It is now widely accepted that remembering the past and imagining the future rely on a number of shared processes and recruit a similar set of brain regions. However, memory and future thinking place different demands on a range of processes. For instance, although remembering should lead to early associative retrieval of event details, event construction may be slower for future events, for which details from different memories are combined. In order to shed light on the question of how the brain distinguishes between memories and future thoughts, we investigated the differences in the electrophysiological correlates of the vivid elaboration of future and past events. In the slow cortical potentials of 24 healthy human participants, differences during early elaboration were observed at temporo-parietal and parieto-occipital electrode sites, presumably reflecting differential recruitment of sensory and semantic detail retrieval. Additional differences emerged over the right pre-frontal cortex during later elaboration, which could be linked to differential retrieval demands. In conclusion, the time course differences, which presumably reflect the varying recruitment of sub-processes engaged during mental time travel, will help to understand the mechanisms with which the brain separates memories from future thoughts.     

Can differences in stress perception and coping explain sex differences in depressive symptoms in adolescents?

A four-year longitudinal study explored the different contribution of low self-esteem, different types of stressors, conflict in close relationships and avoidant coping to the explanation of depressive symptomatology in adolescents. One hundred and ninety adolescents, 101 females and 89 males, participated in four annual assessments using diverse instruments. ANOVAs repeated measurements revealed a higher stress level, more conflicts with mothers and more avoidant coping in females as compared to males at the age of 14 years. Males showed fewer depressive symptoms and higher positive self-esteem at all times. Multiple regression analysis revealed that stress and avoidant coping in early and mid-adolescence explained a significant proportion of depressive symptoms among females in late adolescence. Among males, only the level of conflicts with friends in early adolescence contributed to their level of depressive outcome in late adolescence.     

Can postictal memory predict postoperative memory in patients with temporal lobe epilepsy?

We investigated the contribution of postictal memory testing for lateralizing the epileptic focus and predicting memory outcome after surgery for temporal lobe epilepsy (TLE). Forty‐five patients with TLE underwent interictal, postictal, and postoperative assessment of verbal and nonverbal memory. Surgery consisted of anterior temporal lobectomy (36), selective isolated amygdalohippocampectomy (6), or amygdalohippocampectomy coupled to lesionectomy (3). Postictal and postoperative but not interictal memory were significantly lower in left TLE than in right TLE. Nonverbal memory showed no significant difference in left TLE versus right TLE in all conditions. Postictal memory was significantly correlated with postoperative memory, but the effect disappeared when the lateralization of the focus was considered. Postictal verbal memory is a useful bedside tool that can help lateralize the epileptic focus. Larger studies are needed to further estimate its predictive value of the postoperative outcome.     

Age–sex differences in medicinal self-poisonings

BACKGROUND: Deliberate self-harm (DSH) is related to suicide and DSH repetition is common. DSH hospital presentations are often self-poisonings with medicinal agents. While older age and male sex are known risk factors for suicide, it is unclear how these factors are related to the nature and severity of medicinal self-poisoning (SP). Such knowledge can guide prevention strategies emphasizing detecting and treating mental illness and controlling access to means. METHODS: Medicinal SP presentations by 18,383 residents of Ontario, Canada, aged 12 years and older, who presented to a hospital emergency department in that province between April 1, 2001-March 31, 2002 were characterized by the agents taken, identification of deliberate intent and medical severity. RESULTS: We found distinct age-sex differences in the nature and severity of medicinal SP. In youths, aged 12-17, about 40% of presentations involved analgesics, typically not prescribed and most often the acetaminophen agent-group. Females aged 12-64 were identified as deliberate more often than their male counterparts and this pattern occurred in most agent-groups, even among those who took antidepressants. The acetaminophen agent-group was most consistently associated with medical severity and this effect was strongest among female youths. Although medicinal SP was less frequent in the elderly, these presentations tended to be more medically serious and less often identified deliberate. CONCLUSIONS: The high proportion of medicinal SP in youths involving agents typically not prescribed and the medical severity of the acetaminophen agent-group underscore how prevention strategies must extend beyond controlling access to antidepressants. Despite a higher risk for suicide, males and the elderly may not have their deliberate intent detected and therefore, may not receive appropriate treatment. The emergency department can serve as important link to mental health care and usage patterns can provide feedback about the need for system-level enhancements and DSH surveillance.     

Rural−urban differences in Austrian suicides

Objectives The answer to the question whether suicide rates are higher in urban than in rural areas may have changed over the years. This study analyzes the longitudinal trends of rural and urban suicides in Austria from 1970 to 2005. The most recent decade, 1995–2005 was also investigated cross-sectionally in terms of age groups, gender, suicide methods and family status. Methods Official suicide statistics were calculated in a Poisson regression model to determine trends in suicide rates according to gender in rural and urban regions as well as the ratios of rural- to urban-suicide rates. Population density levels were used as a measure of urbanization. Differences in suicide rates across the rural–urban categories were investigated in terms of genders, age groups, suicide methods and family status using Spearman correlations. Results The ratio of rural to urban suicide rates has continuously increased in both genders over the past 35 years, indicating a growing risk in rural areas. Suicide methods used in rural and urban areas vary significantly and suicide rates among men, but not women, were found to decrease with increasing urbanicity. Conclusion In line with recent findings from other western countries, we showed a growing gap between rural and urban suicide rates. This suggests a need for rural-specific suicide prevention efforts, especially aimed at the male rural population.     

Sex differences in Parkinson’s disease

Sex-related differences in Parkinson’s disease (PD) have been recognised, but remain poorly understood. We aimed to further clarify real-life differences in disease experience according to sex, by evaluating quality of life (QoL), demographic and clinical characteristics of PD patients. A cross-sectional survey was conducted on 210 PD patients (129 men, 81 women) attending specialist neurological clinics across three centres. Outcome measures included the motor examination of the Unified Parkinson’s Disease Rating Scale (UPDRS-III) and QoL as measured by the 39-item Parkinson’s Disease Questionnaire (PDQ-39). A male to female ratio of 1.6:1 was observed. Men reported a greater disease burden than women as noted by higher UPDRS-III scores (27 ± 13 versus 23 ± 13, p = 0.032), daily levodopa equivalent doses (898.1 ± 481.3 mg versus 750.7 ± 427.2 mg, p = 0.037) and caregiver reliance (44% versus 29.5%, p = 0.039). The UPDRS-III score was significantly associated with sex after controlling for age and disease duration, with men more severely affected (β = −0.165, r² = 0.101, p = 0.028). The PDQ-39 showed men reported lower QoL in activities of daily living (ADL), cognition and communication sub-scales (p < 0.05). An association was identified in men between PDQ-39 ADL and cognition sub-scales (r = 0.660, p < 0.001). Men with an appointed caregiver had a higher PDQ-39 Summary Index (t = 3.222, degrees of freedom = 122, p = 0.002). PD was found to have greater overall impact on the health and well-being of male patients in sub-specialty clinical practice. Our study further supports the need for increased sex-delineated clinical assessment and consideration of potential differences required in the management of PD.     

Gender differences in bipolar–II disorder

Gender differences in bipolar–II disorder (BP–II) are understudied. Study aim was to test if there were gender differences in the clinical and family history features of BP–II. Methods Consecutive 374 BP–II private practice outpatients were interviewed by a senior psychiatrist using the Structured Clinical Interview for DSM–IV, modified to improve the detection of BP–II (by Benazzi and Akiskal 2003, J Affect Disord 73:33–38), the Montgomery Asberg Depression Rating Scale (MADRS), the Hypomania Interview Guide, and the Family History Screen. Logistic regression was used to study associations and control for confounding. Alpha level was set at 0.05; P was two–tailed. Results Females represented 67.3% of the group. The female to male ratio was independent of age. Females were more common in younger onset BP–II. Females, versus males, had significantly lower age at onset, more axis I comorbidity, atypical depressions, intra–depression hypomanic symptoms (i. e., mixed depression), and family history of suicidal behavior. On the MADRS, females had more sadness, loss of energy, loss of interest, and suicidal ideas. The symptom structure of hypomanic episodes was similar between females and males. Limitations Single interviewer, outpatient sample, private practice study setting. Discussion Clinical differences were found between BP–II females and males. Differences were found only on the depressive pole of the disorder.However, the magnitude of the differences had not a strong clinical significance, suggesting that at present, on the basis of the variables and the population studied, there is little ground to support a female BP–II depression.     

Delayed recognition memory in Parkinson's disease: a role for working memory?

Immediate and delayed recognition memory for words was examined in a sample of 16 non-demented patients with Parkinson's disease and 16 normal control participants of equivalent age and educational attainment. The patients, relative to control participants, had intact immediate but impaired delayed recognition memory performance. Patients were also impaired on tests of free and cued recall, working memory and a measure of psychomotor processing speed. Processing speed was a significant covariate for delayed recognition, free and cued recall and working memory performance, but not for immediate recognition performance. These results suggest that the same cognitive processes which support performance on tests of recall and working memory also support performance on tests of delayed recognition.     

Beyond individual differences: are working memory and inhibition informative specifiers within ASD?

Findings on working memory (WM) and inhibition in children with autism spectrum disorders (ASD) are contradictory and earlier studies largely ignored individual differences. As WM and inhibition seem to be related, children who experience WM deficits might also experience inhibition deficits. Moreover, these children possibly form a distinct subgroup, differing on other variables, such as cognitive functioning, symptom severity, behavior, and attention deficit hyperactivity disorder (ADHD) characteristics. We studied a large sample of children with and without ASD (8–12 years, IQ > 80) with classic experimental tasks (n-back task, ASD n = 77, control n = 45; stop task, ASD n = 74, control n = 43), and explored individual differences. The ASD group made more errors on the n-back task with increasing WM load, and had longer stop signal reaction times on the stop task when compared with controls. However, only 6 % of the ASD group showed both WM and inhibition deficits, and 71 % showed no deficits. Parents of children with WM and/or inhibition deficits tended to report more conduct problems on the disruptive behavior disorder rating scale. ADHD characteristics did not influence performance. Some children used medication during testing, which seemingly influenced stop task performance, but excluding these data did not change the main findings. Large individual differences in cognitive functioning are present, even within children with ASD with average or above average intelligence. However, whether individual differences in specific cognitive domains, such as WM and inhibition are as informative as individual differences in diagnosis, comorbidity, and general cognitive functioning, calls for future research.     

Regional differences in expression of β-tubulin isoforms in schizophrenia

A growing body of evidence suggests that abnormal elements of the cytoskeleton may be associated with the pathophysiology of schizophrenia. Isoforms of a major cytoskeleton protein, β-tubulin, were recently demonstrated to have distinct roles in neuronal differentiation and cell viability. For these reasons, we tested the hypothesis that there are differences in the expression of β-tubulin isoforms (βI-βIV) in the brain in schizophrenia, using western blot analysis in an elderly group of subjects with this illness and a control group. We found that βI-tubulin protein expression was decreased in the anterior cingulate cortex and increased in the dorsolateral prefrontal cortex, but not changed in superior temporal gyrus or hippocampus in schizophrenia. Our data supports the growing body of evidence suggesting abnormalities of the cytoskeleton in schizophrenia.     

Do memory complaints represent impaired memory performance in patients with major depressive disorder?

Memory complaints are found to be associated with depression. However, the question is, “How much these subjective complaints indicate objective memory impairments?” The aim of this study is to determine whether subjective memory complaints represent objective memory impairments and to establish the demographic and clinical characteristics of patients with major depressive disorder (MDD) and subjective memory complaints. Sixty‐four patients with MDD were assessed for objective memory performance through subtests of the Wechsler Memory Scale‐III. Memory complaints also were assessed in these patients with a structured interview. Thirty healthy controls were also included in the study to compare memory performance among groups. The Hamilton Rating Scale for Depression was used to measure the severity and characteristics of depression. Patients with MDD who had longer duration and earlier onset of depression reported more memory complaints. MDD patients with memory complaints had more hypochondriac concerns but not more depression severity compared with those without memory complaints. There was no relationship between subjective memory complaints and objective memory performance in MDD patients. Patients with MDD with and without memory complaints had lower scores on the Wechsler Memory Scale‐III than the control group. Subjective memory complaints are not a valid indictor of objective memory impairments, and the diagnostic value of self‐reported memory is being questioned in patients with MDD. The cognitive status of MDD patients should be assessed routinely, regardless of the patient awareness of his or her cognitive deficits. Depression and Anxiety, 2008. © 2007 Wiley‐Liss, Inc.     

Any novelty in hippocampal formation and memory?

PURPOSE OF REVIEW: Novel events tend to attract attention and become more effectively encoded in memory than predictable events. The hippocampus and medial-temporal cortical regions, along with regions of the prefrontal cortex, have been associated with enhanced memory for novel events. This review provides an update on recent studies of hippocampal novelty responses in relation to memory. RECENT FINDINGS: Several different types of novelty have been studied. Stimulus novelty effects have been observed as reduced neural activity in the medial-temporal and prefrontal regions when the same stimulus is repeatedly presented. Contextual novelty effects, the detection of a stimulus or event in an unexpected context, is impaired in patients with hippocampal damage. Single-trial analyses of brain activity show that the hippocampus rapidly habituates to contextually novel situations. Associative novelty, the detection of new arrangements of familiar stimuli, has also been related to the medial-temporal regions. A division of labour among the medial-temporal regions has been proposed such that associative novelty selectively engages the hippocampus, whereas stimulus novelty is mediated by the perirhinal cortex. However, a simple account of when the hippocampus versus other medial-temporal cortical regions is recruited awaits further studies. Increased dopaminergic and cholinergic neurotransmission may account for enhanced memory encoding of novel events, and relate to structural neuronal changes. SUMMARY: Interindividual variability in the responsiveness of the hippocampal-novelty system may be genetically mediated, and personality factors can also play a role. A better understanding of such variability can have implications for interventions aimed at supporting memory and for the treatment of drug abuse.     

Molecular control of memory in nematode Caenorhabditis elegans

Model invertebrate organism Caenorhabditis elegans has become an ideal model to unravel the complex processes of memory. C. elegans has three simple forms of memory： memory for thermosensation, memory for chemosensation, and memory for mechanosensation. In the form of memory for mechanosensation, short-term memory, intermediate-term memory, and long-term memory have been extensively studied. The short-term memory and intermediate-term memory may occur in the presynaptic sensory neurons, whereas the long-term memory may occur in the postsynaptic interneurons. This review will discuss the recent progress on genetic and molecular regulation of memory in C. elegans.     

The role of memory in awareness of memory deficits in Alzheimer’s disease,schizophrenia, and brain injury

Patients with neuropsychiatric disorders such as Alzheimer’s disease (AD), schizophrenia (Sz), and brain injury (BI) often show memory deficits and lack of awareness of those deficits. This study aimed to investigate the role of memory in awareness of memory deficits and illness in multiple patient groups. Comparison of awareness profiles between groups can reveal common or distinct patterns of awareness and predictors, which may inform theories about the structure of awareness. Using the same standardized measures, AD (N = 27) Sz (N = 31), and BI (N = 26) patients were compared on memory functioning, awareness of illness, and awareness of memory deficits—measured by discrepancy of pretest estimate and actual test scores. All groups were poor at pretest estimation of memory functioning, particularly the AD and BI groups. In AD, patients with the lowest memory functioning rated their performance highest. The BI group and to a lesser extent the AD group showed improved estimations of performance following the memory test. Those with the poorest memory showed the greatest improvement in ratings accuracy post test. The relationship between memory and awareness of memory was stronger than the association between memory and awareness of illness. There was a double dissociation between awareness of memory and awareness of illness across patient groups. The study shows that awareness of memory is linked to memory functioning, while memory is only modestly related to awareness of illness. Dissociations in the role of memory in different domains of awareness and “online” awareness of performance provide information to refine cognitive models of awareness. However, the results should be interpreted with caution given the heterogeneous nature of the sample.     

Are there gender differences in DSM-IV personality disorders?

This study examined gender differences in DSM-IV personality disorders (PD) in outpatients. Structured diagnostic interviews were reliably administered to a consecutive series of 145 outpatients with a primary axis I diagnosis of binge eating disorder (BED). To further reduce variability due to heterogeneity of axis I, a subgroup of 75 patients with co-occurring major depressive disorder (MDD) was retested for gender differences. Overall, the proportion of males (34.4%) and females (27.4%) diagnosed with any PD did not significantly differ. Specific PD diagnoses were not differentially distributed by gender in the overall study group of patients with BED or in the subgroup of patients with BED and MDD, except for antisocial PD in males.     

Sex differences in psychosis: normal or pathological?

BACKGROUND: Schizophrenia first appears in adolescence, in boys at an earlier age than girls. The interpretation of this key epidemiological finding crucially depends on whether similar age-related sex differences exist in the expression of associated, subclinical psychosis-like experiences. METHODS: Findings are based on a population sample of 2548 adolescents and young adults aged 17-28. Subjects were assessed with the core psychosis sections on delusions and hallucinations of the Munich-Composite International Diagnostic Interview. RESULTS: The risk of subclinical psychotic experiences was significantly higher for males in the younger half of the cohort (17-21 years), but similar in the older half (22-28 years). CONCLUSIONS: These findings suggest that normal maturational changes in adolescence with differential age of onset in boys and girls cause the expression of psychosis, the extreme of which is schizophrenia.