Biomedical subjects

Ramona O Hopkins

Publications and source records attributed to Ramona O Hopkins.

At least 19 recordsLinked to original sources

PubMed2007

Early activity is feasible and safe in respiratory failure patients.

OBJECTIVE: To determine whether early activity is feasible and safe in respiratory failure patients. DESIGN: Prospective cohort study. SETTING: From June 1, 2003, through December 31, 2003, we assessed safety and feasibility of early activity in all consecutive respiratory failure patients who required mechanical ventilation for >4 days admitted to our respiratory intensive care unit (RICU). A majority of patients were treated in another intensive care unit (ICU) before RICU admission. We excluded patients who required mechanical ventilation for < or =4 days. PATIENTS: Eight-bed RICU at LDS Hospital. INTERVENTIONS: We assessed patients for early activity as part of routine respiratory ICU care. We prospectively recorded activity events and adverse events. We defined three activity events as sit on bed, sit in chair, and ambulate. We defined six activity-related adverse events as fall to knees, tube removal, systolic blood pressure >200 mm Hg, systolic blood pressure <90 mm Hg, oxygen desaturation <80%, and extubation. MEASUREMENTS AND MAIN RESULTS: During the study period, we conducted a total of 1,449 activity events in 103 patients. The activity events included 233 (16%) sit on bed, 454 (31%) sit in chair, and 762 (53%) ambulate. In patients with an endotracheal tube in place, there were a total of 593 activity events, of which 249 (42%) were ambulation. There were <1% activity-related adverse events, including fall to the knees without injury, feeding tube removal, systolic blood pressure >200 mm Hg, systolic blood pressure <90 mm Hg, and desaturation <80%. No patient was extubated during activity. CONCLUSIONS: We conclude that early activity is feasible and safe in respiratory failure patients. A majority of survivors (69%) were able to ambulate >100 feet at RICU discharge. Early activity is a candidate therapy to prevent or treat the neuromuscular complications of critical illness.

Accidental Falls↗

PubMed2006

The fate of old memories after medial temporal lobe damage.

Damage to the hippocampal region and related medial temporal lobe structures (perirhinal, entorhinal, and parahippocampal cortices) impairs new learning (anterograde amnesia) as well as memory for information that was acquired before the damage occurred (retrograde amnesia). We assessed retrograde amnesia with the Autobiographical Memory Interview (AMI) and with a news events test in six patients with damage limited primarily to the hippocampal region (H group) and two patients with large medial temporal lobe lesions (MTL group). On the news event test, the H group exhibited temporally limited retrograde amnesia covering approximately 5 years. On the same test, the MTL group exhibited an extensive retrograde amnesia covering decades. Nevertheless, performance was relatively spared for very remote time periods. On the AMI, all patients had intact remote autobiographical memory. Because our patients with hippocampal lesions, as well as our patients with large MTL lesions, performed normally on the AMI, patients who perform poorly on the same test presumably have damage beyond the hippocampus and related structures in the medial temporal lobe. The findings emphasize the difference in the extent of retrograde amnesia associated with hippocampal lesions and large MTL lesions.

Adult↗

PubMed2006

Experience-dependent eye movements, awareness, and hippocampus-dependent memory.

We asked what kind of memory is operating when eye movements change as the result of experience. Participants viewed scenes that were either novel, repeated, or manipulated (i.e., a change was introduced in one region of the scene). Eye movements differed depending on the past viewing history of each scene. Participants made fewer fixations and sampled fewer regions when scenes were repeated than when scenes were novel. When scenes were altered, participants made more fixations in the altered region, spent more time looking at the altered region, and made more transitions into and out of the altered region than in unchanged (matched) regions in the repeated scenes. Importantly, these effects occurred only when individuals were aware that a change had occurred. Participants who were unaware that the scene had been altered looked at the changed scenes in the same way that they looked at repeated scenes. Thus, there was no indication that eye movements could reveal an unaware (unconscious) form of memory. Instead, eye movements reflected conscious memory of whether the scene was repeated or manipulated. The findings were the same when awareness was assessed after viewing all the scenes (experiment 1) and when awareness was assessed after each scene was presented (experiment 2). In experiment 3, memory-impaired patients with damage limited to the hippocampus were impaired at deciding whether scenes were novel, repeated, or manipulated. Thus, the ability to consciously recollect recent encounters with scenes reflects a form of hippocampus-dependent memory. The findings show that experience-dependent eye movements in response to altered scenes reflect conscious, declarative memory, and they support the link between aware memory, declarative memory, and hippocampus-dependent memory.

Adult↗

PubMed2006

Single-item memory, associative memory, and the human hippocampus.

We tested recognition memory for items and associations in memory-impaired patients with bilateral lesions thought to be limited to the hippocampal region. In Experiment 1 (Combined memory test), participants studied words and then took a memory test in which studied words, new words, studied word pairs, and recombined word pairs were presented in a mixed order. In Experiment 2 (Separated memory test), participants studied single words and then took a memory test involving studied word and new words. In a separate test, they studied word pairs and then took a memory test involving studied word pairs and recombined word pairs. In both experiments, patients were impaired at memory for single items as well as memory for associations, suggesting that the hippocampus is important for both of these memory functions. In Experiment 1, patients appeared to be more impaired at associative memory than item memory. In Experiment 2, patients were similarly impaired at associative memory and item memory. These different findings are considered, including the fact that in Experiment 1 the results depended on the fact that controls produced unexpectedly low false-alarm rates to recombined pairs. We discuss single-item and associative memory from the perspective that the hippocampus and adjacent cortex work cooperatively to signal recognition and that simple dichotomies do not adequately describe the division of labor within the medial temporal lobe.

Adult↗

PubMed2006

Item memory, source memory, and the medial temporal lobe: concordant findings from fMRI and memory-impaired patients.

We studied item and source memory with fMRI in healthy volunteers and carried out a parallel study in memory-impaired patients. In experiment 1, volunteers studied a list of words in the scanner and later took an item memory test and a source memory test. Brain activity in the hippocampal region, perirhinal cortex, and parahippocampal cortex was associated with words that would later be remembered (item memory). The activity in these regions that predicted subsequent success at item memory predicted subsequent source memory to a similar degree. In experiment 2, memory-impaired patients with damage thought to be limited to the hippocampal region were given an item memory test and a source memory test, as in experiment 1. The patients were similarly impaired on the item memory test and the source memory test. Together, the findings suggest that medial temporal lobe structures broadly support recognition memory function and that item memory and source memory similarly depend on these structures.

Adult↗

PubMed2006

Cognitive, emotional, and quality of life outcomes in patients with pulmonary arterial hypertension.

BACKGROUND: The effects of pulmonary arterial hypertension on cardiovascular and physical function are well documented. Limited information exists regarding the effects of pulmonary arterial hypertension on cognitive function despite patient reports of problems with memory and attention. Our primary purpose was to determine if a prospectively identified cohort of pulmonary arterial hypertension patients had cognitive sequelae. Our secondary purpose was to determine the relationships between cognitive sequelae and neuropsychological test scores with depression, anxiety, and quality of life. METHODS: Forty-six adults with pulmonary arterial hypertension underwent assessment of cognitive function, depression, anxiety, and quality of life using standardized neuropsychological tests and questionnaires. The patients' scores were compared to normal population data. Medical, affective, neuropsychological, and quality of life data for patients with and without cognitive sequelae were compared using analysis of variance, Chi-square, or Fisher exact tests for categorical data. Correlations assessed relationships between neuropsychological test scores, depression, anxiety, quality of life, and medical data. RESULTS: Cognitive sequelae occurred in 58% (27/46) of the pulmonary arterial hypertension patients. Patients with cognitive sequelae had worse verbal learning, delayed verbal memory, executive function, and fine motor scores compared to patients without cognitive sequelae. Twenty-six percent of patients had moderate to severe depression and 19% had moderate to severe anxiety. Depression, anxiety and quality of life were not different for patients with or without cognitive sequelae. Our patients had decreased quality of life, which was associated with worse working memory. CONCLUSION: Patients with pulmonary arterial hypertension have cognitive impairments, depression, anxiety, and decreased quality of life. Depression, anxiety, and quality of life were similar for patients with cognitive sequelae compared to those without cognitive sequelae. Decreased quality of life was associated with worse verbal and working memory. Clinicians should be aware of adverse brain related outcomes in PAH patients. Attention to proximal determinants and possible interventions to prevent or reduce cognitive and emotional morbidity and decreased quality of life are warranted and should be an emphasis in outcomes research.

Adult↗

PubMed2006

Strategies in probabilistic categorization: results from a new way of analyzing performance.

The "Weather Prediction" task is a widely used task for investigating probabilistic category learning, in which various cues are probabilistically (but not perfectly) predictive of class membership. This means that a given combination of cues sometimes belongs to one class and sometimes to another. Prior studies showed that subjects can improve their performance with training, and that there is considerable individual variation in the strategies subjects use to approach this task. Here, we discuss a recently introduced analysis of probabilistic categorization, which attempts to identify the strategy followed by a participant. Monte Carlo simulations show that the analysis can, indeed, reliably identify such a strategy if it is used, and can identify switches from one strategy to another. Analysis of data from normal young adults shows that the fitted strategy can predict subsequent responses. Moreover, learning is shown to be highly nonlinear in probabilistic categorization. Analysis of performance of patients with dense memory impairments due to hippocampal damage shows that although these patients can change strategies, they are as likely to fall back to an inferior strategy as to move to more optimal ones.

Adult↗

PubMed2006

Intact visual perception in memory-impaired patients with medial temporal lobe lesions.

A recent proposal that structures of the medial temporal lobe support visual perception in addition to memory challenges the long-standing idea that the ability to acquire new memories is separable from other cognitive and perceptual functions. In four experiments, we have put this proposal to a rigorous test. Six memory-impaired patients with well characterized lesions of either the hippocampal region or the hippocampal region plus additional medial temporal lobe structures were assessed on difficult tests of visual perceptual discrimination. Across all four experiments, the patients performed as well as controls. The results show that visual perception is intact in memory-impaired patients with damage to the medial temporal lobe even when perception is assessed with challenging tasks. Furthermore, the results support the principle that the ability to acquire new memories is a distinct cerebral function, dissociable from other perceptual and cognitive functions.

Aged↗

PubMed2006

Mnemonic functions of the hippocampus: a comparison between animals and humans.

This review summarizes a series of experiments aimed at answering the question whether the hippocampus in rats and humans performs parallel functions focusing on studies that assess spatial and temporal pattern separation, sequential learning, spatial and temporal pattern association, spatial and temporal pattern completion, and short-term and intermediate-term memory. It is recognized that a comparison of the functions of the rat hippocampus with human hippocampus is difficult, because of differences in methodology, differences in complexity of life experiences, and differences in the degree of hippocampal damage as well as damage to interconnected brain regions. Yet, in general the data support the idea that with respect to spatial and temporal pattern separation, sequential learning, spatial and temporal pattern associations, spatial and temporal pattern completion, and short-term and intermediate-term memory, similar functions are observed in rats and humans with hippocampal damage using analogous tasks. These data provide support for evolutionary continuity in cognitive function assigned to the hippocampus of rats and humans.

Animals↗

PubMed2006

The hippocampus supports both the recollection and the familiarity components of recognition memory.

The receiver operating characteristic (ROC) has been used to investigate the component processes of recognition memory. Some studies with this technique have been taken to indicate that the hippocampus selectively supports the process of recollection, whereas adjacent cortex in the parahippocampal gyrus supports the process of familiarity. We analyzed ROC data from young adults, memory-impaired patients with limited hippocampal lesions, and age-matched controls. The shape of the ROC changed in similar ways from asymmetric to symmetric, as a function of the strength of memory (strong to weak) in both the young adults and the patients. Moreover, once overall memory strength was similar, the shape of the patient ROC was asymmetric and matched the control ROC. These results suggest that the component processes that determine the shape of the ROC are operative in the absence of the hippocampus, and they argue against the idea that the hippocampus selectively supports the recollection process.

Adult↗

PubMed2006

Quality of life, emotional abnormalities, and cognitive dysfunction in survivors of acute lung injury/acute respiratory distress syndrome.

This article provides a brief discussion of the recent literature linking quality-of-life impairment to physical dysfunction after acute lung injury/acute respiratory distress syndrome. Its main focus is a review of the current knowledge concerning cognitive and emotional outcomes after lung injury and their impact on long-term quality of life.

Affective Symptoms↗

PubMed2006

Formation and validation of a telephone battery to assess cognitive function in acute respiratory distress syndrome survivors.

PURPOSE: Describe initial development and validation of a test battery composed of established instruments designed to detect, via telephone interview, cognitive abnormalities in survivors of acute respiratory distress syndrome. METHODS: Two cross-sectional studies were performed, including the following phases: (1) initial battery construction, (2) feasibility, (3) item reduction, (4) convergent and divergent validity, and (5) telephone administration compared with in-face interviews in a separate population. RESULTS: There was a broad range of cognitive function detected in the derivation population, and all subjects completed the interview. There was convergence of cognitive impairment with moderate/severe anxiety (P = .008), the Sickness Impact Profile Psychosocial Summary Score (mean difference, 15.3; 95% CI, 7.74-22.9; P = .0001), and the mental health domains of the Short Form 36. Subjects with cognitive impairment had no detectable difference in the physical function domains of the Short Form 36. When administered to the validation population, telephone tests of memory, attention, reasoning, and executive functions had good intraclass correlation with the in-face interviews (P < .01). CONCLUSIONS: Detection of cognitive abnormalities in acute respiratory distress syndrome survivors using a telephone-administered test battery derived from standard cognitive tests is feasible and has evidence of construct validity. This battery may be useful as a research tool when in-face interviews are not feasible.

Adult↗

PubMed2006

Basal ganglia lesions following carbon monoxide poisoning.

PRIMARY OBJECTIVES: Carbon monoxide (CO) is the most common cause of poisoning and may result in basal ganglia lesions. This study reviewed the literature of carbon monoxide poisoning and basal ganglia lesions and prospectively assessed the prevalence of basal ganglia lesions in a cohort of patients with CO poisoning. RESEARCH DESIGN: Literature review and prospective cohort study. METHODS: This study conducted a comprehensive review of the literature and assessed 73 CO-poisoned patients for basal ganglia lesions on sequential MR scans. Magnetic resonance scans were obtained on day 1, 2 weeks and 6 months post-CO poisoning. RESULTS: The literature review found basal ganglia lesions occur in 4-88% of subjects. Only one patient was found with globus pallidus lesions at 2 weeks and 6 months following CO poisoning, that were not present on the initial day 1 MR scan. CONCLUSIONS: Basal ganglia lesions, including lesions of the globus pallidus, may be less common than previously reported.

Adolescent↗

PubMed2006

Brain atrophy and cognitive impairment in survivors of Acute Respiratory Distress Syndrome.

PRIMARY OBJECTIVES: Acute Respiratory Distress Syndrome (ARDS) is characterized by severe acute lung injury, hypoxemia and is associated with neurological and cognitive impairments. This study assessed quantitative brain and ventricular volumes in survivors of ARDS with brain computed tomography (CT) scans compared to normal controls. It also compared the medical and cognitive outcome data of patients with ARDS with and without CT scans. RESEARCH DESIGN: Observational cohort study. METHODS: Sixty-six consecutive acute respiratory distress patients, of which 15 patients with ARDS underwent brain CT and 51 patients had no brain imaging. Brain CT scans from 15 survivors of ARDS were compared to age- and sex-matched normal controls. Clinical radiological findings and ventricular volumes, brain volume and generalized brain atrophy. RESULTS: The patients with ARDS and brain imaging had cognitive impairments, significant brain atrophy, ventricular enlargement and 53% had atrophy or lesions by radiological report. CONCLUSIONS: Clinicians need to be aware that ARDS can cause significant long-term brain-related morbidity manifest by brain atrophy, lesions and neurocognitive impairments.

Acute Disease↗

PubMed2006

Assessing neurocognitive outcomes after critical illness: are delirium and long-term cognitive impairments related?

PURPOSE OF REVIEW: Critically ill patients have a high risk of developing neurologic dysfunction including delirium and long-term cognitive impairment. In this paper we examine possible relationships between delirium and long-term cognitive impairments and explore this in the context of critical illness. RECENT FINDINGS: Critical illness and its treatment can lead to neurologic morbidity including neuropathological abnormalities, delirium, and cognitive impairments. The association between delirium and long-term cognitive impairments has been shown in a number of populations. Among intensive care unit cohorts, delirium appears to be one of many possible causes of cognitive impairments and may be a leading modifiable cause. The mechanisms of both delirium and intensive care unit related cognitive impairment remain unclear, although a variety of common mechanisms have been proposed. SUMMARY: Potential neurologic consequences of critical illness include delirium and long-term cognitive impairments. Defining the extent of their association in intensive care unit cohorts is an important research priority due to the high prevalence of delirium and persistent cognitive impairments in critically ill patients. Future research should focus on strategies for the early identification of delirium and cognitive impairments, elucidating mechanisms of brain injury, and the development and implementation of therapeutic modalities designed to prevent or decrease delirium and cognitive morbidity.

Cognition Disorders↗

PubMed2006

Prevalence of white matter hyperintensities in a young healthy population.

BACKGROUND AND PURPOSE: White matter hyperintensities (WMHs) are bright objects observed in the white matter on brain magnetic resonance (MR) imaging. WMHs are often reported as "normal" findings but may represent pathological changes. The prevalence of WMHs appears to increase with increasing age although both the typical timing and clinical significance of their appearance among medically and neurologically healthy persons remains unclear. We assessed the prevalence of WMHs in a cohort of younger healthy subjects. METHODS: Our study comprised 243 healthy subjects ages 16-65 years from our prospective normative MR imaging database. MR scans were rated for presence of periventricular and centrum semiovale WMHs using a four-point visual semi-quantitative scale. RESULTS: WMHs occurred in 5.3% (13 of 243) of subjects. All WMHs were small (rating of 0.5) except one subject age 65 years who had large WMHs (ratings of 2). The median age for subjects with no WMHs was 34.5 years compared to 57.0 years for subjects with WMHs. There were no gender differences (P= .76). Older age correlated with presence of WMHs (r = 0.24; P= .01). Age greater than 55 years had a 10-fold increase in the prevalence of WMHs compared to age < or =55 years (odds ratio = 10.01; 95% confidence interval = 3.1-32.3; P < .001). CONCLUSION: WMHs were uncommon in a younger healthy population screened for comorbid diseases, but increased 10-fold in subjects over 55 years of age. When present, the WMHs are generally small (rating of 0.5). While large WMHs appear to be associated with cognitive deterioration, the optimum threshold for identification, clinical significance, and prognostic value of smaller white matter changes requires further research.

Adolescent↗

PubMed2006

Neuroimaging, cognitive, and neurobehavioral outcomes following carbon monoxide poisoning.

Carbon monoxide is a colorless, odorless gas produced as a byproduct of combustion. Carbon monoxide is the leading cause of poisoning injury and death worldwide. Morbidity following CO poisoning includes neurologic sequelae, neuropathologic abnormalities on brain imaging, neurobehavioral changes, and cognitive impairments. It is estimated that as high as 50% of individuals with carbon monoxide poisoning will develop neurologic, neurobehavioral, or cognitive sequelae. Carbon monoxide related cognitive impairments included impaired memory, attention, executive function, motor, visual spatial, and slow mental processing speed. Given the high rate of brain related morbidity and the fact that the majority of carbon monoxide is avoidable, awareness and prevention of carbon monoxide poisoning is warranted.

Brain Injuries↗

PubMed2006

Long-term neurocognitive function after critical illness.

BACKGROUND: Until relatively recently, critical care practitioners have focused on the survival of their patients and not on long-term outcomes. The incidence of chronic neurocognitive dysfunction has been underestimated and underreported, and only recently has it been studied in critically ill patients. However, neurocognitive outcomes have been the subject of extensive investigation in other medical populations for many years. METHODS: Review of the current literature regarding long-term neurocognitive outcomes following critical illness. RESULTS: Data from studies to date indicate that critical illness can lead to significant neurocognitive impairments. The neurocognitive impairments persist for months and years, and may have important consequences for quality of life, the ability to return to work, overall functional ability, and substantial economic costs. The mechanisms of the neurocognitive impairments are not fully understood but likely include delirium, hypoxia, glucose dysregulation, metabolic derangements, inflammation, and the effects of sedatives and narcotics among other factors. The contributions of these factors may be particularly significant in patients with preexisting vulnerabilities for the development of cognitive impairments such as mild cognitive impairment, dementia, prior traumatic brain injury, or other comorbid disorders associated with neurocognitive impairments. CONCLUSIONS: Current research indicates that neurocognitive sequelae following critical illness are common, may be permanent, and are associated with impairments in daily function, decreased quality of life, and an inability to return to work. Research needs to be done to better understand the prevalence, nature, risk factors, and nuances of the neurocognitive impairments observed in ICU survivors.

Central Nervous System↗