Molar and latent models of cognitive slowing: Implications for aging,dementia, depression,development, and intelligence

The time that it takes a group of participants to respond in simple cognitive tasks varies systematically with the identity of the group. For example, on most tasks, older adults take longer to respond than younger adults. Similarly, on most tasks, younger children take longer to respond than mature children. More generally, response time has been found to vary reliably with a number of other factors that differentiate groups of participants, including the levels of dementia, depression, and intelligence. For each factor, investigators have sought to determine whether the various mental processes are slowed identically as the level of impairment increases. They have based this determination largely on the relation between the overall response times of the relevant groups. Here it is shown how one can base this determination on the relation between the speeds of the individual latent or mental processes governing the performance of the target groups. Such a shift in emphasis has three important advantages: it reduces the possibility of falsely accepting or rejecting the hypothesis that all processes are slowed identically; it pinpoints the actual processes that are lengthened disproportionately when processes are not slowed identically; and it makes possible the rigorous testing of the effects of changes in speed on other dependent variables (e.g., accuracy).     

Infectious and immune factors in the pathogenesis of neurodevelopmental disorders: epidemiology, hypotheses, and animal models

Both genetic and environmental factors contribute to the pathogenesis of a wide variety of neurodevelopmental disorders, including autism, mental retardation, and schizophrenia. Some heritable disorders approach 100% penetrance; nonetheless, even in these disorders, subtle aspects of clinical disease expression may be influenced by the environment. In other disorders with genetic influences, exogenous factors, and the timepoint(s) during nervous system development at which they are introduced, modulate expression of disease. Elucidation of the mechanisms guiding this intricate interplay between host response genes, environmental agents, and the neurodevelopmental context within which these interactions occur, is necessary to understand the continuum of clinical outcomes. This chapter will review the evidence that infectious and immune factors may contribute to the pathogenesis of neurodevelopmental disorders, describe an animal model of neurodevelopmental disorders based upon viral infection, identify processes by which neural circuitry may be compromised, and outline areas for future research.     

Emotion-induced amnesia in rats: working memory-specific impairment, corticosterone-memory correlation, and fear versus arousal effects on memory

We have shown previously that psychological stress (predator exposure) impairs spatial memory in rats. We have extended that finding here to show that predator stress selectively impaired recently acquired (hippocampal-dependent) spatial working memory without affecting long-term (hippocampal-independent) spatial reference memory. We also investigated why predator exposure impairs memory. Was spatial memory impaired because of the fear-provoking aspects of predator exposure or only because the cat was a novel and arousing stimulus? If the latter possibility was correct, then any novel and arousing stimulus, independent of its emotional valence (i.e., aversive or appetitive), would impair memory. We found that spatial working memory was not impaired when the male rats were exposed to a sexually receptive female rat, a stimulus that was novel and arousing to them, but not aversive. We also found that there was an equivalent increase in serum corticosterone levels in male rats exposed to either a cat or a female rat, but only the cat-exposed rats exhibited a significant correlation between corticosterone levels and impaired memory. Overall, this series of experiments demonstrates that (1). predator stress selectively impaired working (hippocampal-dependent), but not reference (hippocampal-independent), memory; (2). a fear-provoking stimulus, and not merely novelty and increased arousal, impaired spatial memory; and (3). increased corticosterone levels correlated with impaired spatial working memory only under predator exposure, that is, fear-provoking conditions.     

Assessing social dysfunction: the contributions of laboratory and performance-based measures

Reviewed research studies in which laboratory and performance-based measures were used with success to identify problematic social interaction patterns and social skills deficits associated with poor peer relationships. However, the clinical utility of these measures remains an empirical question. In this article, social competence is conceptualized as an organizational construct, reflecting the child's capacity to integrate behavioral, cognitive, and affective skills to adapt flexibly to diverse social contexts and demands. Correspondingly, performance-based measures of social functioning that include complex social interaction stimuli and require integrative responses appear more likely to demonstrate social validity than measures focused on isolated behaviors or cognitions. Research studies are reviewed that involve observations of children in three types of analogue social situations: play groups, friendship pairs, and social-challenge situations. In addition, studies that have utilized performance-based measures to screen and evaluate children for social skills training programs are reviewed. We conclude that performance-based measures are unlikely to be useful in determining whether a child is experiencing social dysfunction but may enhance the clinical analysis of the nature of the child's social difficulties. We identify gaps in the current knowledge regarding the clinical utility of performance-based measures of social dysfunction, along with directions for future research.     

A study of mild cognitive impairment in veterans: role of hypertension and other confounding factors

Introduction: Hypertension has shown to be an important risk factor for the decline in cognitive function. Aim of our study is to investigate the presence of cognitive impairment of the elders with hypertension and other confounding factors.

Methods: This study was conducted on 400 veterans who were matched one-to-one with the confounding factors for assessing the presence of mild cognitive impairment using both MMSE and Montreal Cognitive Assessment (MoCA). The 13 related factors of patient data were studied.

Results: The prevalence rate of cognitive impairment was 29.25%. Age (OR 2.679, 95%CI 1.663–6.875), sleep impairment (OR 1.117, 95%CI 1.754–7.422), uncontrolled hypertension (OR 1.522, 95%CI 1.968–4.454), type 2 diabetes (OR 2.464, 95%CI 1.232–4.931), and hyperlipidaemia (OR 1.411, 95%CI 1.221–8.988) are the risk factors for the cognitive deterioration, while the protective factors are high level of education (OR 0.032, 95%CI 0.007–0.149) and regular exercise (OR 0.307, 95%CI 0.115–0.818).

Discussion: Because some vascular disease risk factors, such as hypertension, can be treated effectively, cognitive decline related to these risk factors, and vascular disease per se, may be prevented or its course modified through more aggressive treatment and improved compliance.     

The Tower of London Test: different scoring criteria for diagnosing Alzheimer's disease and mild cognitive impairment

The Tower of London (TOL) is used for evaluating planning skills, which is a component of the executive functions. Different versions and scoring criteria were developed for this task, and some of them present with different psychometrical properties. This study aimed to evaluate two specific scoring methods of the TOL in diagnosing Mild Cognitive Impairment and probable Alzheimer's disease. The TOL total scores from 60 patients of each diagnosis were compared with the performance of 60 healthy-aged controls using receiver operating characteristics analysis and multinomial logistic regression. Krikorian method better diagnosed Alzheimer's disease, while Portellas's was better at discriminating healthy controls from Mild Cognitive Impairment, but were not efficient at comparing this last group with Alzheimer's patients. Regression analysis indicates that in addition to screening tests, TOL improves the classification of the three groups. The results suggest the two scoring methods used for this task may be useful for different diagnostic purposes.     

A comparison of the diagnostic accuracy of the AD8 and BCAT-SF in identifying dementia and mild cognitive impairment in long-term care residents

We compared the accuracy of the Brief Cognitive Assessment Tool—Short Form (BCAT-SF) and AD8 in identifying mild cognitive impairment (MCI) and dementia among long-term care residents. Psychometric analyses of 357 long-term care residents (n = 228, nursing home; n = 129, assisted living) in Maryland referred for neuropsychological evaluation evidenced robust internal consistency reliability and construct validity for the BCAT-SF. Furthermore, hierarchical logistic regression and receiver operating characteristic curve analyses demonstrated superior predictive validity for the BCAT-SF in identifying MCI and dementia relative to the AD8. In contrast, previously reported psychometric properties or cut scores for the AD8 could not be cross-validated in this long-term care sample. Based on these findings, the BCAT-SF appears to be a more reliable and valid screening instrument than the AD8 for rapidly identifying MCI and dementia in long-term care residents.     

Reflections on dynamics,adaptation and control: A cognitive architecture for mental models

In this paper, an overview of the wide variety of occurrences of mental models in the literature is discussed. They are classified according to two dimensions obtaining four categories of them: static-dynamic and world-mental, where static refers to mental models for static world states or for static mental states and dynamic refers to mental models for world processes or for mental processes. In addition, distinctions are made for what can be done by mental models: they can, for example, be (1) used for internal simulation, they can be (2) adapted, and these processes can be (3) controlled. This leads to a global three-level cognitive architecture covering these three ways of handling mental models. It is discussed that in this cognitive architecture reflection principles play an important role to define the interactions between the different levels.     

Gene x environment interaction and cognitive performance: animal studies on the role of corticosterone

A fundamental question in the neurobiology of cognition is how stress and glucocorticoids modify learning and memory processes. Why some individuals develop cognitive deficits after stress, while other individuals improve in cognitive performance under similar adverse conditions is still unresolved. To address these questions we focus on those issues. First, corticosterone, which appears to be the preferred glucocorticoid for the rodent and human brain, acts via brain mineralocorticoid (MR) and glucocorticoid receptors (GR) on the expression of networks of corticosteroid-responsive genes. Different effects are achieved by MR and GR activation. Second, the experimental context that determines the timing and the consequences of corticosterone action during the various stages of information processing is reviewed. Third, the genetic context and the environmental context are investigated. Using apolipoprotein E knockout (apoE0/0) mice we show that apoE (apoE4 is a genetic risk factor for Alzheimer's disease) is a candidate gene with an important function in shaping the cognitive outcome (genotype x environment interaction).     

Peripheral vision: The effects of developmental,perceptual, and cognitive factors

The effects of perceptual and cognitive factors on information processing in the visual periphery were studied in 5- and 8-year-old children and in adults. Subjects judged either the similarity (Study 1) or the identity (Study 2) of geometric forms. In both studies, two forms were simultaneously presented for 20 msec at 2, 4, or 6°, with one form on either side of the fovea. Type of form and Axis of presentation were varied. Both studies demonstrated declining performance with increasing distance, poorer performance with open than closed forms, poorest performance along the vertical axis, and no major interaction of these factors with age. Greater “flattening” of the visual field was found in Study 2 than in Study 1 for all age groups. The results indicate that the parafoveal visual field is elliptical and that more difficult tasks accentuate this asymmetry. This effect of task demands on the relative flatness of the effective visual field cannot be interpreted on the basis of anatomical factors. The findings indicated striking developmental similarity in the effect of several variables on parafoveal processing and challenge the idea of greater tunnel vision in preschoolers than in adults. Further, the data suggest that perceptual and cognitive factors influence the size and shape of the effective visual field across the full age range studied.     

The mind beyond our immediate awareness: Freudian, Jungian, and cognitive models of the unconscious

Abstract: Several branches of cognitive science now focus on the nature of the unconscious. This paper explores some of the findings and models from this research. By introducing formulations based on non‐clinical data, the cognitive scientists—in neural linguistics, computational modelling, and neuroscience—may depart from the older psychoanalytic formulations. An understanding of unconscious neural processes is nevertheless emerging showing how synapses are modified by experience and how learning, conscious and unconscious, is due to this important aspect of brain plasticity. Freud and Jung's formulations about the unconscious psyche, representing the main tenets of depth psychology, are also based on a conception of the mind as extending beyond immediate awareness. However, their models are more hypothetical in that their data, almost exclusively, come from treatments of psychotherapy patients and their verbal accounts. So how do these two conceptions of the unconscious match, where do they differ? And how does the neural understanding in the present research support theories and practices of analytic treatments?     

Medical burden, cerebrovascular disease, and cognitive impairment in geriatric depression: modeling the relationships with the CART analysis

Herein, the background information reflecting roles of medical burden, cerebrovascular disease and risk factors, and cognitive impairment in geriatric depression are reviewed. The authors then propose a nonparametric statistical approach to the data analysis of multiple putative causal variables for late-life depression, the Classification and Regression Tree Analysis. This analysis presents a useful approach to modeling nonlinear relationships and interactions among variables measuring physical and mental health, as well as magnetic resonance imaging and cognitive measures in depressed elderly. This method uncovers the existing interactions among multiple predictor variables, and provide thresholds for each variable, at which its predictive power becomes statistically significant. It presents a "hierarchy" of the predictors in a form of a decision tree by finding the best combination of predictors of an outcome. The authors present two models based on demographic variables, measures of vascular and nonvascular medical burden, neuroimaging indices, the Mini-Mental State Examination score, and neuropsychological test scores of 81 elderly depressed subjects. Cognitive tests of verbal fluency and executive function are identified as the best predictors of depression, followed by the frontal lobe volume and Mini-Mental State Examination. The authors observed that an interaction between frontal lobe volume, total lesion volume, and medical burden was predictive of depression.     

The use of structural equation models in Consumer Psychology: A methodological dialogue on its contributions,cautions, and concerns

The goal of Consumer Psychology is to use manipulations and measures in order to make inferences as to the psychological processes that underlie consumer behavior. A statistical tool available to do so is Structural Equation Modeling (SEM). Recent issues of this journal have provided primers in the use of SEM. Herein, three noted experts provide further guidance and philosophical consideration of the issues associated with SEM, as well as statistical and methodological concerns in general. The goal of this dialogue is to provide a foundation for the use of SEM in Consumer Psychology and the Social Sciences in general.     

Influences of preclinical dementia and impending death on the magnitude of age-related cognitive deficits

The authors examined the influence of preclinical dementia and impending death on the cross-sectional relationship between age and performance in tasks assessing episodic memory, visuospatial skill, and verbal fluency. Increasing age was associated with a general decrease in cognitive performance. In addition, those who were to be diagnosed with dementia or had died by a 3-year follow-up, were older, and performed at a lower level than the remaining sample across all cognitive tasks at baseline. Nevertheless, removal of the preclinical dementia and impending death groups from the original sample affected the cross-sectional age-cognition relations relatively little. This pattern of findings suggests that the biological aging process exerts negative influences on cognitive functioning beyond those resulting from disease and mortality.     

The impact of perceptual, cognitive and motor factors on bimanual coordination

Bimanual coordination is governed by constraints that permit congruent movements to be performed more easily than incongruent movements. Theories concerning the origin of these constraints range from low level motor-muscle explanations to high level perceptual–cognitive ones. To elucidate the processes underlying coordinative constraints, we asked subjects to use a pair of left–right joysticks to acquire corresponding pairs of congruent and incongruent targets presented on a video monitor under task conditions designed to systematically modulate the impact of several perceptual–cognitive processes commonly required for bimanual task performance. These processes included decoding symbolic cues, detecting goal targets, conceptualizing movements in terms of goal target configuration, planning movement trajectories, producing saccades and perceiving visual feedback. Results demonstrate that constraints arise from target detection and trajectory planning processes that can occur prior to movement initiation as well as from inherent muscle properties that emerge during movement execution, and that the manifestation of these constraints can be significantly altered by the ability to visually monitor movement progress.     

Pathways to childhood depressive symptoms: the role of social, cognitive, and genetic risk factors

Childhood depressive conditions have been explored from multiple theoretical approaches but with few empirical attempts to address the interrelationships among these different domains and their combined effects. In the present study, the authors examined different pathways through which social, cognitive, and genetic risk factors may be expressed to influence depressive symptoms in 300 pairs of child twins from a longitudinal study. Path analysis supported several indirect routes. First, risks associated with living in a step- or single-parent family and punitive parenting did not directly influence depressive outcome but were instead mediated through maternal depressive symptoms and child negative attributional style. Second, the effects of negative attributional style on depressive outcome were greatly exacerbated in the presence of precipitating negative life events. Third, independent of these social and cognitive risk mechanisms, modest genetic effects were also implicated in symptoms, with some indication that these risks are expressed through exposure to negative stressors. Together, these routes accounted for approximately 13% of total phenotypic variance in depressive symptoms. Theoretical and analytical implications of these results are discussed in the context of several design-related caveats.     

Alcohol effects on performance monitoring and adjustment: affect modulation and impairment of evaluative cognitive control

Alcohol is known to impair self-regulatory control of behavior, though mechanisms for this effect remain unclear. Here, we tested the hypothesis that alcohol's reduction of negative affect (NA) is a key mechanism for such impairment. This hypothesis was tested by measuring the amplitude of the error-related negativity (ERN), a component of the event-related brain potential (ERP) posited to reflect the extent to which behavioral control failures are experienced as distressing, while participants completed a laboratory task requiring self-regulatory control. Alcohol reduced both the ERN and error positivity (Pe) components of the ERP following errors and impaired typical posterror behavioral adjustment. Structural equation modeling indicated that effects of alcohol on both the ERN and posterror adjustment were significantly mediated by reductions in NA. Effects of alcohol on Pe amplitude were unrelated to posterror adjustment, however. These findings indicate a role for affect modulation in understanding alcohol's effects on self-regulatory impairment and more generally support theories linking the ERN with a distress-related response to control failures.     

Lexical access and the brain: anatomical constraints on cognitive models of word recognition.

Recent studies in the cognitive psychology of reading and many other skilled performances have been dominated by models inspired by neural connectivity (e.g., McClelland & Rumelhart, 1986). Such models have not yet begun to consider the accumulating evidence of considerable anatomical localization of component cognitive operations in the human brain (e.g., Posner, Petersen, Fox, & Raichle, 1988). In this article we apply anatomical findings to the job of building computational models of visual word recognition. Brain imaging studies already provide important constraints on how lexical access should be defined in terms of isolable encoding operations that compute the visual form, phonology, and semantics of words. Brain imaging studies also speak to issues of modularity versus interaction between these encoding operations, distribution versus localization of processing within the operations, and orchestration of operations to accomplish different word processing tasks. We conclude that a combined cognitive and anatomical analysis may be of considerable benefit in developing more adequate models of human information processing.