Biomedical subjects

Faith Gunning-Dixon

Publications and source records attributed to Faith Gunning-Dixon.

9 recordsLinked to original sources

PubMed2005

Executive dysfunction and the course of geriatric depression.

BACKGROUND: Executive dysfunction is common in geriatric depression and persists after improvement of depressive symptoms. This study examined the relationship of executive impairment to the course of depressive symptoms among elderly patients with major depression. METHODS: A total of 112 nondemented elderly patients with major depression participated in an 8-week citalopram trial at a target daily dose of 40 mg. Executive functions were assessed with the initiation/perseveration subscale of the Dementia Rating Scale and the Stroop Color-Word test. Medical burden was rated with the Cumulative Illness Rating Scale. RESULTS: Both abnormal initiation/perseveration and abnormal Stroop Color-Word scores were associated with an unfavorable response of geriatric depression to citalopram. In particular, initiation/perseveration scores below the median (< or =35) and Stroop scores at the lowest quartile (< or =22) predicted limited change in depressive symptoms. Impairment in other Dementia Rating Scale cognitive domains did not significantly influence the outcome of depression. CONCLUSIONS: Executive dysfunction increases the risk for poor response of geriatric depression to citalopram. Because executive functions require frontostriatal-limbic integrity, this observation provides the rationale for investigation of the role of specific frontostriatal-limbic pathways in perpetuating geriatric depression. Depressed elderly patients with executive dysfunction require vigilant clinical attention because they might be at risk to fail treatment with a selective serotonin reuptake inhibiting antidepressant.

Aged↗

PubMed2004

Aging, sexual dimorphism, and hemispheric asymmetry of the cerebral cortex: replicability of regional differences in volume.

We examined age-, sex-, and hemisphere-related differences in the cerebral cortex. Volumes of the cerebral hemispheres and 13 regions of interest (ROIs) were measured on magnetic resonance images of 200 healthy adults. The strength of association between age and volume differed across ROIs. The lateral prefrontal cortex exhibited the greatest age-related differences, whereas significantly weaker associations were observed in the prefrontal white matter, sensory-motor, and visual association regions. The hippocampal shrinkage was significant in people in their mid-fifties. The primary visual, anterior cingulate, the inferior parietal cortices, and the parietal white matter showed no age-related differences. The pattern of age-related regional differences replicated the findings previously obtained on an independent sample drawn from the same population. Men evidenced larger volumes in all ROIs except the inferior parietal lobule, even after sexual dimorphism in body size was statistically controlled. In some regions (hippocampus and fusiform gyrus) men exhibited steeper negative age-related trends than women. Although a typical pattern of global hemispheric asymmetry was observed, the direction and magnitude of regional volumetric asymmetry was as inconsistent as in the previous reports. Thus, a pattern of age-related shrinkage suggesting increased vulnerability of the lateral prefrontal cortex to aging appears stable and replicable, whereas little consistency exists in sex-related and hemispheric differences in regional cortical volumes.

Aged↗

PubMed2003

Reversed cerebellar asymmetry in men with first-episode schizophrenia.

BACKGROUND: Abnormalities in cerebellar structure and function have been implicated in the pathophysiology of schizophrenia. In this study, we investigated whether patients experiencing first-episode schizophrenia differed from healthy comparison subjects in regional cerebellar volumes or cerebellar asymmetry. METHODS: Volumes of four cerebellar regions (right, left; anterior, posterior) were measured from contiguous coronal magnetic resonance (MR) images in 69 (37 men, 32 women) patients experiencing first-episode schizophrenia and in 49 (27 men, 22 women) healthy comparison subjects. Patients were rated on the Scale for the Assessment of Negative Symptoms and the Schedule for Affective Disorders and Schizophrenia-Psychosis/Disorganization before the initiation of antipsychotic medication and at the time of the MR imaging exam. RESULTS: Patients and healthy comparison subjects did not differ in regional cerebellar volumes, but male patients demonstrated significantly reversed anterior and posterior asymmetry compared with healthy male subjects. Among male patients, greater reversals in a composite measure of cerebellar asymmetry (i.e., torque) correlated significantly with increased negative symptoms before the initiation of antipsychotic medication. CONCLUSIONS: These findings implicate an aberrant neurodevelopmental process involving the metencephalon in the pathophysiology of schizophrenia and are consistent with prior studies implicating abnormal asymmetry in schizophrenia at the neocortical level.

Adult↗

PubMed2003

Lack of normal association between cerebellar volume and neuropsychological functions in first-episode schizophrenia.

OBJECTIVE: Functional neuroimaging studies have identified a role for the cerebellum in the neuropsychology of schizophrenia. Few studies, however, have examined the relationship between cerebellar size and neuropsychological functioning in schizophrenia. The authors' goal was to examine this relationship in patients and healthy comparison subjects. METHOD: Total cerebellar volume was computed from magnetic resonance images in 48 male and 33 female patients experiencing a first episode of schizophrenia and in 14 male and nine female healthy comparison subjects. Patients and comparison subjects completed a comprehensive neuropsychological assessment encompassing six domains of functioning: executive, motor, language, visuospatial, memory, and attention. A global domain of functioning was computed as the mean of these six domains. RESULTS: Larger cerebellar volume correlated significantly with better global functioning in healthy subjects but not among patients with schizophrenia; this relationship was significantly stronger in healthy subjects than in patients. Additional analyses revealed significant associations between cerebellar volume and visuospatial, executive, and memory functions in healthy volunteers but not among patients. CONCLUSIONS: The cerebellum plays a role in higher cognitive functions in healthy individuals, and normal associations between cerebellar size and function are absent in patients experiencing a first episode of schizophrenia. These findings are consistent with neurobiological models implicating the cerebellum in the pathogenesis of schizophrenia.

Adult↗

PubMed2003

Differential aging of the human striatum: longitudinal evidence.

BACKGROUND AND PURPOSE: Information about age-related changes in the striatum comes almost exclusively from cross-sectional studies. We examined age-related differences and longitudinal changes in the volume of the striatal nuclei, compared longitudinal measures of changes with their cross-sectional estimates, and addressed the question of differential aging of the basal ganglia. METHODS: We measured the volumes of the caudate nucleus (head), the putamen, and the globus pallidus on MR images of 53 healthy adults whose ages at baseline ranged between 20 and 77 years. The measurements were conducted twice, 5 years apart. RESULTS: On both measurement occasions, the volume of the neostriatal nuclei (caudate and putamen) but not of the globus pallidus correlated negatively with age. However, longitudinal comparison revealed significant declines in the neostriatal volumes and smaller (but statistically significant) shrinkage of the paleostriatum. In 5 years, the striatal components (caudate, putamen, and globus pallidus) shrunk by 1.21, 0.85, and 0.55 standard deviation units, respectively. The average annual shrinkage rate was 0.83% in the caudate nucleus, 0.73% in the putamen, and 0.51% in the globus pallidus. CONCLUSION: Although cross-sectional estimates suggested preservation of some striatal nuclei, longitudinal shrinkage of the whole striatum was evident even in a selected group of healthy adults. Moreover, the magnitude of observed longitudinal change was greater than predicted from cross-sectional studies.

Adult↗

PubMed2002

Prefrontal volumes in habitually violent subjects with antisocial personality disorder and type 2 alcoholism.

Pathology of the prefrontal cortices has been suggested to be a part of neural networks underlying deviant behavioral patterns. Recently, reduced overall prefrontal cortical volumes have been proposed in subjects with antisocial personality disorder (ASP). It is not known whether there are specific patterns of volume loss within the prefrontal regions. Nor is it known if there are correlations between the prefrontal volumes and degree of psychopathology. In this study, total prefrontal, prefrontal white, and cortical (dorsolateral, orbitofrontal, medial frontal) prefrontal volumes were measured from magnetic resonance images in 24 non-psychotic, violent male subjects who had a diagnosis of ASP in combination with type 2 alcoholism, and 33 age-matched control males. The degree of psychopathy in the ASP subjects was assessed using the Psychopathy Checklist-Revised (PCL-R). Compared with the controls, the ASP subjects had significantly smaller volumes of all three cortical regions on the left, but this significance disappeared after controlling for differences in education and duration of alcoholism. For the dorsolateral and orbitofrontal cortices, only duration of alcoholism was significantly associated with the observed volume deficit, and for the medial frontal cortex it was the difference in education. Thus, the observed volume deficits in this sample were related more to alcoholism or differences in education rather than to the diagnosis of ASP. Moreover, no significant correlations between any of the volumes and the degree of psychopathy were found.

Adult↗

PubMed2002

Age-related differences in the course of cognitive skill acquisition: the role of regional cortical shrinkage and cognitive resources.

This study examined the impact of age-related differences in regional cerebral volumes and cognitive resources on acquisition of a cognitive skill. Volumes of brain regions were measured on magnetic resonance images of healthy adults (aged 22-80). At the early stage of learning to solve the Tower of Hanoi puzzle, speed and efficiency were associated with age, prefrontal cortex volume, and working memory. A similar pattern of brain-behavior associations was observed with perseveration measured on the Wisconsin Card Sorting Test. None of the examined structural brain variables were important at the later stages of skill acquisition. When hypertensive participants were excluded, the effect of prefrontal shrinkage on executive aspects of performance was no longer significant, but the effect of working memory remained.

Adult↗

PubMed2002

Sex differences in temporo-limbic and frontal brain volumes of healthy adults.

Sex differences have been observed in neurobehavioral measures and in neuroanatomic studies. Men and women differ in emotion processing, including perception, experience and expression, most notably reflected in greater male aggression. We examine temporo-limbic and prefrontal structures volumetrically in a large well-characterized sample of healthy adults, applying morphometric methods across cerebral regions that regulate emotions. Quantitative magnetic resonance imaging (MRI) was performed in 116 healthy adults, 57 men and 59 women, age range 18-49 years. We used reliable methods of region of interest identification to examine sex differences in volume of temporo-limbic and frontal regions. An automated tissue segmentation procedure was used to obtain separate measurements for gray and white matter. After correcting for cranial volume, men and women had identical volumes of amygdala and hippocampus, as well as dorsal prefrontal cortex. However, women had larger orbital frontal cortices than men, resulting in highly significant difference in the ratio of orbital gray to amygdala volume (P = 0.002). The larger volume of cortex devoted to emotional modulation may relate to behavioral evidence for sex differences in emotion processing.

Adolescent↗

PubMed2002

Working memory for complex figures: an fMRI comparison of letter and fractal n-back tasks.

n-back letter and fractal tasks were administered to 11 participants during functional magnetic resonance imaging to test process specificity theories of prefrontal cortex (PFC) function and assess task validity. Tasks were matched on accuracy, but fractal n-back responses were slower and more conservative. Maintenance (1-back minus 0-back) activated inferior parietal and dorsolateral PFC, with additional activation in right ventrolateral PFC during letter n-back and left lingual gyrus during fractal n-back. Maintenance plus manipulation (2-back minus 0-back) activated inferior parietal, Broca's area, insula, and dorsolateral and ventral PFC, with greater right dorsolateral PFC activation for letter n-back. Manipulation only (2-back minus 1-back) produced additional and equivalent dorsolateral PFC and anterior cingulate activation in both tasks. Results support fractal n-back validity and indicate substantial overlap in working memory functions of dorsal and ventral PFC.

Adult↗