Rebecca K. MacAulay

A Longitudinal Study on Dual-Tasking Effects on Gait: Cognitive Change Predicts Gait Variance in the Elderly

Neuropsychological abilities have found to explain a large proportion of variance in objective measures of walking gait that predict both dementia and falling within the elderly. However, to this date there has been little research on the interplay between changes in these neuropsychological processes and walking gait overtime. To our knowledge, the present study is the first to investigate intra-individual changes in neurocognitive test performance and gait step time at two-time points across a one-year span. Neuropsychological test scores from 440 elderly individuals deemed cognitively normal at Year One were analyzed via repeated measures t-tests to assess for decline in cognitive performance at Year Two. 34 of these 440 individuals neuropsychological test performance significantly declined at Year Two; whereas the “non-decliners” displayed improved memory, working memory, attention/processing speed test performance. Neuropsychological test scores were also submitted to factor analysis at both time points for data reduction purposes and to assess the factor stability overtime. Results at Year One yielded a three-factor solution: Language/Memory, Executive Attention/Processing Speed, and Working Memory. Year Twos test scores also generated a three-factor solution (Working Memory, Language/Executive Attention/Processing Speed, and Memory). Notably, language measures loaded on Executive Attention/Processing Speed rather than on the Memory factor at Year Two. Hierarchal multiple regression revealed that both Executive Attention/Processing Speed and sex significantly predicted variance in dual task step time at both time points. Remarkably, in the “decliners”, the magnitude of the contribution of the neuropsychological characteristics to gait variance significantly increased at Year Two. In summary, this study provides longitudinal evidence of the dynamic relationship between intra-individual cognitive change and its influence on dual task gait step time. These results also indicate that the failure to show improved test performance (particularly, on memory tests) with repeated administrations might prove to be useful of indicator of early cognitive decline.

Longitudinal assessment of neuropsychological and temporal/spatial gait characteristics of elderly fallers: taking it all in stride

Gait abnormalities are linked to cognitive decline and an increased fall risk within older adults. The present study addressed gaps from cross-sectional studies in the literature by longitudinally examining the interplay between temporal and spatial aspects of gait, cognitive function, age, and lower-extremity strength in elderly “fallers” and “non-fallers”. Gait characteristics, neuropsychological and physical test performance were examined at two time points spaced a year apart in cognitively intact individuals aged 60 and older (N = 416). Mixed-model repeated-measure ANCOVAs examined temporal (step time) and spatial (stride length) gait characteristics during a simple and cognitive-load walking task in fallers as compared to non-fallers. Fallers consistently demonstrated significant alterations in spatial, but not temporal, aspects of gait as compared to non-fallers during both walking tasks. Step time became slower as stride length shortened amongst all participants during the dual task. Shorter strides and slower step times during the dual task were both predicted by worse executive attention/processing speed performance. In summary, divided attention significantly impacts spatial aspects of gait in “fallers”, suggesting stride length changes may precede declines in other neuropsychological and gait characteristics, thereby selectively increasing fall risk. Our results indicate that multimodal intervention approaches that integrate physical and cognitive remediation strategies may increase the effectiveness of fall risk interventions.

The paradox of schizotypy: Resemblance to prolonged severe mental illness in subjective but not objective quality of life

An interesting paradox has emerged regarding the schizophrenia-spectrum. Put simply, college students with schizotypy (defined as the personality organization reflecting a vulnerability to schizophrenia-spectrum pathology) report experiencing pathology with respect to some key functional domains on a level that is equal to or more severe than older, outpatients with an prolonged psychiatric disorders. Notably, this self-reported pathology is not supported by objective/behavioral performance data, suggesting that the primary deficit is psychological in nature (e.g., metacognition). We evaluated whether this subjective-objective dysjunction extends to quality of life (QOL). Eighty-three college students with schizotypy were compared to 50 outpatients with severe mental illness (SMI) as well as to 82 undergraduate and 34 community control groups in subjective and objective QOL via a modified version of Lehman׳s Quality of Life Interview, which covers a range of QOL domains. The schizotypy and SMI group were equally impoverished in all measures of subjective QOL compared to the college and community control groups. In contrast, the schizotypy group was relatively normal in most measures of objective quality of life compared to the SMI group. The subjective-objective dysjunction appears to extend to QOL, and these differences do not appear to reflect a more global negativistic reporting bias.

The normalities and abnormalities associated with speech in psychometrically-defined schizotypy

Speech deficits are thought to be an important feature of schizotypy--defined as the personality organization reflecting a putative liability for schizophrenia. There is reason to suspect that these deficits manifest as a function of limited cognitive resources. To evaluate this idea, we examined speech from individuals with psychometrically-defined schizotypy during a low cognitively-demanding task versus a relatively high cognitively-demanding task. A range of objective, computer-based measures of speech tapping speech production (silence, number and length of pauses, number and length of utterances), speech variability (global and local intonation and emphasis) and speech content (word fillers, idea density) were employed. Data for control (n=37) and schizotypy (n=39) groups were examined. Results did not confirm our hypotheses. While the cognitive-load task reduced speech expressivity for subjects as a group for most variables, the schizotypy group was not more pathological in speech characteristics compared to the control group. Interestingly, some aspects of speech in schizotypal versus control subjects were healthier under high cognitive load. Moreover, schizotypal subjects performed better, at a trend level, than controls on the cognitively demanding task. These findings hold important implications for our understanding of the neurocognitive architecture associated with the schizophrenia-spectrum. Of particular note concerns the apparent mismatch between self-reported schizotypal traits and objective performance, and the resiliency of speech under cognitive stress in persons with high levels of schizotypy.

Illusory superiority and schizotypal personality: explaining the discrepancy between subjective/objective psychopathology.

An interesting paradox has emerged from the literature regarding schizotypy--defined as the personality organization reflecting a putative liability for schizophrenia--spectrum disorders. Across certain cognitive, emotional, quality of life, and other functional variables, individuals with schizotypy report experiencing relatively severe levels of pathology. However, on objective tests of these same variables, individuals with schizotypy perform largely in the healthy range. These subjective impairments are paradoxical in that individuals with schizotypy, typically recruited from undergraduate college populations, should be healthier in virtually every conceivable measure compared to chronic, older outpatients with severe mental illness. The present study evaluated the idea that the subjective deficits associated with schizotypy largely reflect a lack of illusory superiority bias-a normally occurring bias associated with an overestimation of self-reported positive qualities and underestimation of negative qualities compared to others. In the present study, both state-measured using laboratory emotion-induction methods-and trait positive and negative emotion was assessed across self (e.g., how do you feel at this moment?) and other (e.g., how do most people feel at this moment?) domains in 39 individuals with self-reported schizotypy and 39 matched controls. Controls demonstrated an illusory superiority effect across both state and trait measures whereas individuals with schizotypy did not. These results were not explained by severity of mental health symptoms. These results suggest that a cognitive bias, or lack thereof, is a marker of schizotypy and a potential target for further research and therapy.

Conceptualizing schizotypal ambivalence: factor structure and its relationships.

Abstract Ambivalence is an important facet of pathology that has received limited attention despite its importance in understanding negative emotionality within schizophrenia spectrum disorders. Central to understanding the role of ambivalence in schizophrenia is characterizing its manifestation within schizotypal individuals—those with the purported genetic liability for schizophrenia. The present study used the Schizotypal Ambivalence Scale (SAS) to examine the nature of ambivalence. An exploratory factor analysis of SAS scores revealed three factors: interpersonal, indecision, and contradictory feelings of ambivalence. Group differences in SAS scores were found such that psychometrically defined schizotypal individuals reported higher levels of ambivalence than controls, and different schizotypy traits exhibited different relationships with SAS factors and quality of life. The inclusion of implicit and explicit measures of positive and negative attitudes revealed that individuals with schizotypy might lack insight into their affective experiences as suggested by the incongruence between our explicit and implicit measures of social attitudes. As hypothesized, the Schizotypal Personality Questionnaire trait dimensions associated with greater SAS ambivalence and the different trait dimensions of schizotypy showed both common and disparate relationships with the ambivalence factors. The current results support the notion that schizotypal ambivalence is a multifaceted construct that not only is affective but also reflects broader processes that dynamically interact with one another to influence functional outcomes.

Neurocognitive underpinnings of language disorder: Contrasting schizophrenia and mood disorders

Language disorder is a deleterious, but poorly understood, symptom of schizophrenia. Burgeoning research suggests that it also occurs in depression and bipolar disorders. Building on prior research, the present study evaluated the degree to which language disorder was associated with neurocognitive deficits in a sample of patients with schizophrenia and mood disorders. Employed in this study were a standard neurocognitive battery and a behavior-based analysis of language disorder from natural speech. Speech samples were collected from two separate counterbalanced conditions administered a week apart. During an “activity” speech condition, participants discussed their daily activities, hobbies and interests. During a “social” speech condition, participants discussed social relationships from their lives. The schizophrenia and mood disorder groups were similar in severity of language disorder during the activity condition. However, there was a significant difference in the severity of language disorder within the schizophrenia patient group but not the mood disorder group. For patients with schizophrenia, language disorder was associated with a range of neurocognitive deficits for both the activity and social speech conditions. For patients with mood disorders, language disorder was significantly associated with poorer neurocognitive functioning during the activity condition, conversely it was significantly associated with better neurocognitive functioning during the social condition. These findings highlight the importance of neurocognition for understanding language disorder across a wide swath of severe mental illnesses. They also emphasize how mitigating factors that exacerbate language disorder may differ in patients with schizophrenia versus mood disorders. Directions for future research are discussed.

Understanding Anhedonia: The Role of Perceived Control

Perceived control appears to play an important role in the manifestation of anhedonic symptoms, as it is integrally related to underlying neurobiological reward systems and motivated behaviors. Perceived control refers to the conscious process by which an event is determined to be manageable, or more simply put, it can be thought of as the extent to which an individual/organism believes that he/she has the resources and capability to manage an event. Consequentially, perceived control has a rich history in the depression literature (e.g., learned helplessness) and appears to be an important determinant in the manifestation of anhedonia. However, to this date, the link between perceived control and anhedonia remains unclear. In order to further elucidate this relationship, this chapter provides a model that seeks to explain perceived control’s role in determining our psychological and behavioral responses to stress. To do so, we will discuss shared neurobiological mechanisms (i.e., the mesocorticolimbic system) in relation to how they pertains to perceived control and approach-avoidance motivation. Additionally, clinical implications will be discussed through the framework of perceived control’s impact on specific coping strategies.

Unexpected speech performance under high- versus low-cognitive load in psychometric schizotypy

Participants: o Schizotypy groups: • N=14 with predominantly negative symptoms with mean age(SD)= 18.5(1.2); %male=29; %Caucasian=93) • N=25 with predominantly non-negative symptoms (positive and/or disorganized) with mean age (SD)=18.7(1.3);%male=44; %Caucasian=68 o Control group: N =34 individuals with mean age(SD)=19.1(2.4); %male=38; %Caucasian=81 o Recruitment strategy based on SPQ-BR scores described in Cohen, et al., 2012 o No significant group differences in age, gender, or ethnic composition (p’s > .05)