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Biomedical subjects

A R Dobbs

Publications and source records attributed to A R Dobbs.

15 recordsLinked to original sources
PubMed2001

Working memory deficits associated with chronic fatigue syndrome.

Cognitive impairments are among the most frequently reported and least investigated components of the chronic fatigue syndrome (CFS). As part of a multifaceted study of the CFS, the present study investigated the cognitive functioning of chronic fatigue patients. The performance of 20 CFS patients was compared to that of controls (N = 20) on 4 tests of working memory (WM). Digit Span Forward was used to assess the storage capacity of WM. Multiple aspects of central executive functioning were assessed using several standard measures: Digit Span Backward, and Trails A and Trails B. More recently developed measures of WM were used to assess control of processing under temporal demands (working memory task) and resistance to interference (a sustained attention task). Deficits were restricted to more demanding tasks, requiring resistance to interference and efficient switching between processing routines. The overall results clearly implicate deficits in the control aspects of central executive function in CFS.

Adolescent↗
PubMed1998

A comparative approach to identify unsafe older drivers.

The identification of unsafe older drivers is a current and important challenge. In the present research, a comparative approach was used in which the on road driving errors and expert evaluations of older drivers with clinically significant declines in mental abilities (N = 155) were compared to the errors and evaluations of a normal elderly control group (N = 68) and a normal younger control group (N = 30). The results indicate that the conventional criteria used in North America for licensing new drivers is inappropriate for license removal in experienced drivers. The results also indicate that hazardous errors were the single best indicator of membership in the group of older drivers with clinical impairment. This group also differs from the two normal control groups on turn positioning errors, minor positioning errors and overcautiousness. All groups differ from each other on scanning errors. A regression analysis further indicated that the five driving errors listed above accounted for over 57% of the variance associated with global ratings provided by expert driving instructors.

Accidents, Traffic↗
PubMed1997

Classification and staging of dementia of the Alzheimer type: a comparison between neural networks and linear discriminant analysis.

OBJECTIVE: To examine the utility of artificial neural networks (ANNs) for differentiating patients with Alzheimer disease from healthy control subjects and for staging the degree of dementia. DESIGN: Comparison of the classification abilities of ANNs with the statistical technique of linear discriminant analysis (LDA) using the results of 11 neuropsychological tests as predictors. PARTICIPANTS: Ninety-two patients with a diagnosis of probable Alzheimer disease (referred from a geriatric clinic) and 43 elderly control subjects (independently solicited). The patients met National Institute of Neurological and Communicative Disorders and Stroke-Alzheimer's Disease and Related Disorders Association criteria for probable dementia, with clinical ratings of dementia severity derived from the Cambridge Examination for Mental Disorders of the Elderly (CAMDEX). MAIN OUTCOME MEASURES: Classifications between and within groups were determined by using LDA and ANNs, and more detailed comparisons of the 2 methods were performed by using chi2 analyses and unweighted and weighted kappa statistics. RESULTS: Linear discriminant analysis correctly identified 71.9% of cases. Artificial neural networks, trained to classify the subjects using the same data, correctly classified 91.1% of the cases. Subsidiary analyses showed that although both techniques effectively discriminated between the control subjects and patients with dementia, the ANNs were more powerful in discriminating severity levels within the dementia population. The analyses for goodness of fit revealed that the ANN classification produced a better fit to the actual data. A comparison of the weighted proportion of agreement between the criterion and predictor variables also showed that the ANNs clearly outperformed LDA in classification accuracy for the full data set and patients-only data set. CONCLUSION: The results demonstrate the utility of ANNs for group classification of patients with Alzheimer disease and elderly controls and for staging dementia severity using neuropsychological data.

Aged↗
PubMed1997

Evaluating the driving competence of dementia patients.

The driving behaviors of dementia patients have received little in the way of empirical scrutiny except through retrospective reports of crash rates. Understanding the driving errors of dementia patients and how they differ from those of normal older and younger drivers is important. This knowledge is basic to the development of road tests and scoring procedures to evaluate the driving competence of older, experienced drivers, especially those whose fitness to drive may have been compromised by a medical illness that alters their mental abilities. We have drive tested over 100 currently driving elderly patients with clinically significant cognitive decline (mostly diagnosed as the early stages of Alzheimer disease) and compared their performance with that of normal drivers. The study identified the types of driving errors that distinguish and differentiate the cognitively impaired group as well as a set of driving errors typical of both cognitively impaired and normal experienced drivers but differing in the number and severity of errors. A set of errors was also identified that did not differentiate the groups and should not be used in evaluating a person's competence to drive.

Adult↗
PubMed1994

Age differences in the interpretation of misaligned "You-Are-Here" maps.

"You-Are-Here" (YAH) maps, common in shopping malls and office buildings, are difficult to interpret if not aligned with their surroundings. Younger and older adults made direction decisions after viewing simple maps representing a university campus. YAH arrows were either upright and coordinated with viewer position or contra-aligned 180 degrees. Contra-alignment caused subjects, especially older adults, to take more time and be less accurate. Women were slower on contra-aligned maps, although no less accurate, than men. The need to mentally realign such incongruent maps in order to make correct direction decisions can cause serious difficulty for older adults trying to navigate through large, complex environments.

Adult↗
PubMed1993

Parental presence during treatment of the child patient: a study with British parents.

A clinical study was carried out to determine if parental presence during dental treatment alters the child's behaviour when compared with parental absence. Thirty-two children who attended with a parent for a dental recall visit were randomly assigned to a parent present or a parent absent group. The age of the children ranged from 4 to 12 years. Twenty-three mothers and nine fathers attended during the study. Those parents absent during the visit viewed proceedings from behind a one-way mirror. Each visit was standardised in procedure and recorded on video tape. The results showed that 4 to 8-year-old children exhibited significantly more negative behaviour, regardless of parental presence, than the 9 to 12-year-olds. The presence of the parent did not lead to significantly greater negative behaviour. The parent's need to see what happened during the visit and the child's need to have a parent present were the most important reasons for having a parent present. Parents viewing from behind a one-way mirror were as satisfied with their position as parents who had been actually present in the surgery.

Age Factors↗
PubMed1993

Age differences in word finding in discourse and nondiscourse situations.

Measures of word finding in discourse (video description task) and nondiscourse situations (word fluency tasks) were obtained from a sample of 90 community-dwelling healthy adults. Age differences were found in the accuracy and uncertainty of the labels used to refer to the characters and objects depicted in the video description task and in the number of correct responses in the category fluency task. There was a significant amount of shared variance between the 2 types of tasks. More important, there was a significant amount of variance in the video discourse task associated with age that was independent of performance in the word fluency task. The communicative impact of a word-finding problem and need for discourse level study are discussed.

Adult↗
PubMed1992

Communicative function in patients with questionable Alzheimer's disease.

The communicative skills of patients with questionable Alzheimer's disease (AD) were examined by having patients describe events shown in a silent video cartoon. As anticipated, questionable AD patients provided fewer clauses in their descriptions than did education- and age-matched controls. This finding was independent of differences in word finding ability. More important, the patients failed to describe as many of the thematically important events as did the controls, a difference that affected the overall informativeness of the communication. Even though the patients were sensitive to event importance, there was no evidence of compensation in their descriptions (i.e., a greater concentration of important events). Several interpretations are presented that focus on possible deficits in the pragmatic or semantic systems of language or both as an early symptom of Alzheimer's disease.

Aged↗
PubMed1992

The impact of pacemaker implantation on cognitive functioning in elderly patients.

OBJECTIVE: To describe and quantify the impact of pacemaker implantation on cognitive functioning in the elderly. DESIGN: Prospective case-control, non-randomized trial. Data were collected from clinical and family interviews and from a psychological test battery. SETTING: Pacemaker clinic in a tertiary care hospital. PARTICIPANTS: Nineteen elderly (65+ years) patients undergoing new or replacement pacemaker implantation for dysrhythmias and volunteer controls matched for age, sex, and short Mental Status Questionnaire test results, without dysrhythmia or intervention. MAIN OUTCOME MEASURES: Subjective and clinical impressions based on family interviews; results of psychological test battery before and 6-12 months after pacemaker implantation. RESULTS: Prior to pacemaker implantation, three patients met DSM-III criteria for dementia and two for delirium. Paced patients demonstrated deficiency in immediate memory, language, memory for less structured information, and learning of abstract materials. These deficits were due primarily to the poor performance of patients with complete heart block. Despite clinical and subjective impressions of improvement, there was no change in psychologic test performance subsequent to pacemaker implantation. CONCLUSIONS: Impaired cognitive functioning is not always clinically apparent but appears common in patients with cardiac dysrhythmias; it is not altered 6-12 months after pacemaker implantation.

Aged↗
PubMed1992

Design of institutions: cognitive functioning and social interactions of the aged resident.

Older people experience sensory, cognitive, and social deficits that adversely affect their interaction with the environment. Design of institutions for the elderly resident should be prosthetic to ensure that environments optimally accommodate the functioning of the residents. The sensory and cognitive state of the residents should be considered in every facility. This review discusses how sensory and cognitive changes in aging affect orientation and wayfinding as well as how the physical aspects of the environment can accommodate these changes to reduce confusion and disorientation. Environmental features that promote social interaction are reviewed. Because the environmental needs and unique characteristics of the cognitively impaired resident differs from that of the nonimpaired resident, special issues in the design of facilities for demented residents are reviewed. Conclusions are offered with regard to research needs and applied problems.

Aged↗
PubMed1990

Age and sex differences in the mental realignment of maps.

Community-residing young and elderly persons were given six maps with routes indicated by lines connecting dots. The dots were arranged in a 3 x 3 matrix that corresponded to the placement of discs affixed to the testing room floor. Route lengths increased by one segment with each subsequent map. In one condition participants were instructed not to turn the map while walking the indicated route and thus the orientation of the map to the room varied as the person followed the path. In a second condition participants turned the map while following the route, keeping it aligned with the room. Elderly persons made fewer correct choices and took more time to make direction decisions than younger people as did females compared to males. When the map could not be turned, decision times were related to the amount of misalignment between the map and the room. Elderly persons, especially females were influenced more by map misalignment than were young people. The results indicate that mental realignment is an important aspect of route following and may explain some of the difficulty older people have with such tasks.

Adult↗
PubMed1989

Attentional demands of visual word recognition.

Becker's (1976, 1979, 1980, 1985; Becker & Killion, 1977; Eisenberg & Becker, 1982) verification model was used as a framework to investigate the attentional demands of word recognition. In two experiments, a lexical decision task and an auditory probe task were performed in single- and dual-task conditions. Responses to probes were divided into detection and movement measures that indexed the demands of recognition and response output, respectively. In Experiment 1, single- to dual-task decrements in probe detection performance were larger during low-frequency as compared with high-frequency trials. This finding indicates that the attentional demands of word recognition vary with word frequency. These findings were replicated in Experiment 2, which was designed to separate a response compatibility and a capacity interpretation of the results. The findings are interpreted within Becker's verification model.

Adult↗
PubMed1989

Adult age differences in working memory.

Active and passive measures of short-term memory over a large segment of the adult life span were compared. Two hundred twenty-eight volunteers, aged 30 to 99 years, performed the digit span forward and backward task, the Peterson-Peterson task, and a new working memory task in which active manipulation of information is emphasized. Age differences were slight for passive tasks. For the working memory task, significant declines were found between the ages of 60 to 69 and 70+ years. It is suggested that the age differences may be due to a decrease in the flexibility with which processing changes are made.

Adult↗
PubMed1989

Laypersons' knowledge about the sequelae of minor head injury and whiplash.

Even minor head injuries can result in the post traumatic syndrome, a symptom complex that includes physical discomfort and sleep, sexual, affective, and memory disturbance. Little is known about the layperson's knowledge of the syndrome but this may influence judgements about malingering and attitudes towards victims of minor head injury. Descriptions of rear-end automobile accidents were presented to two groups. One group (n = 22) rated the likelihood of a variety of physical, affective, cognitive, and distractor (never or rarely reported by trauma victims) symptoms. A second group (n = 21) judged the speed necessary to cause each of the symptoms. The results indicated that highly exaggerated speeds were thought necessary to produce even the most common physical symptoms. Moreover, cognitive symptoms were thought to be no more likely than were distractor symptoms. In contrast, the knowledge about physical symptoms, the effects of loss of consciousness and whiplash versus direct head injuries was consistent with what is known from research literature.

Adult↗