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Biomedical subjects

M P McAndrews

Publications and source records attributed to M P McAndrews.

16 recordsLinked to original sources
PubMed2005

Comparing language lateralization determined by dichotic listening and fMRI activation in frontal and temporal lobes in children with epilepsy.

We investigated the relationship between ear advantage scores on the Fused Dichotic Words Test (FDWT), and laterality of activation in fMRI using a verb generation paradigm in fourteen children with epilepsy. The magnitude of the laterality index (LI), based on spatial extent and magnitude of activation in classical language areas (BA 44/45, 21/22, 39) differed significantly for patients classified with unilateral left, compared to bilateral, language representation based on FDWT scores. Concordance with fMRI was higher for those classified with unilateral left, than bilateral language representation on the FDWT. Of note, asymmetry in temporal lobe, rather than frontal lobe, activation was more strongly related to the LI from the dichotic listening test. This study shows that the FDWT can provide a quick and valid estimate of lateralization in pre-surgical candidates, which can be readily adopted for other clinical or research purposes when an estimate of language dominance is desired.

Brain Mapping↗
PubMed2002

Encoding and retrieval in aging and memory loss, a fMRI study.

Mild cognitive impairment (MCI) is a term for nondemented individuals with memory complaints and deficits greater than age-adjusted normal performance. Functional MRI (fMRI) may be a more sensitive method than other techniques to reveal functional abnormalities in individuals with MCI, only a proportion of whom progress to Alzheimer's disease (AD). fMRI was carried out while subjects (four MCI, five age-matched normal controls, and one AD) performed incidental encoding (deep and shallow) and recognition tasks for colored and black and white photographs contrasted to baseline fixation. fMRI revealed interesting dissociations between activation patterns and behavioral performance when comparing the MCI and AD to the NC.

Aging↗
PubMed2001

Functional MRI of phonological and semantic processing in temporal lobe epilepsy.

Phonological and semantic aspects of language were examined in patients with unilateral temporal lobe epilepsy (TLE) and healthy controls using functional MRI. We expected to replicate previous findings in healthy individuals showing relatively greater activation in frontal regions for phonological compared with semantic processing, and greater activation in temporal regions for semantic compared with phonological processing. We hypothesized that differences between patients with left TLE and healthy controls would be found in the pattern of left temporal cortical activation associated specifically with semantic processing. Patients with right TLE were included as a seizure control group. All TLE patients previously showed left hemisphere language dominance on intracarotid sodium amytal studies. Greater blood oxygen level dependent activation was found during phonological processing compared with semantic processing in frontal regions for healthy participants but, contrary to expectation, semantic processing did not lead to increased temporal lobe activity relative to phonological processing. Furthermore, no differences between left temporal patients and controls were found specifically in left temporal cortex. Rather, patients with left temporal seizure foci showed significantly greater left dorsolateral prefrontal activity compared with controls, as well as increased signal change in left inferior frontal and right middle temporal gyrus. Surprisingly, patients with right, but not left, TLE showed poorer performance on the linguistic tasks compared with controls, as well as a decrease in right superior temporal activation. The results converge with studies of dyslexic patients showing increased left frontal activity in the presence of left temporal dysfunction and are suggestive of both inter- and intra-hemispheric functional reorganization of language representation in left TLE.

Adolescent↗
PubMed2000

Remote episodic memory deficits in patients with unilateral temporal lobe epilepsy and excisions.

The nature of remote memory impairment in patients with medial temporal lobe damage is the subject of some debate. While some investigators have found that retrograde amnesia in such patients is temporally graded, with relative sparing of remote memories (Squire and Alvarez, 1995), others contend that impairment is of very long duration and that remote memories are not necessarily spared (Sanders and Warrington, 1971; Nadel and Moscovitch, 1997). In this study, remote memory was assessed in 25 patients with unilateral temporal lobe epilepsy and 22 non-neurologically impaired controls using the Autobiographical Memory Interview (Kopelman et al., 1989). Results indicate that patients have impaired personal episodic memory but intact personal semantic memory. The impairment extends even to the most remote time periods in early childhood, long before seizure onset in many patients. As well, patients awaiting temporal lobectomy for control of seizures perform as poorly as those who have already undergone resective surgery. These results support the hypothesis that temporal lobe damage or dysfunction, caused by recurrent seizures or surgical excision, results in extensive retrograde amnesia for personal episodic memories. Interestingly, patients with radiological evidence of hippocampal sclerosis were not significantly more impaired than those without obvious sclerosis. These results indicate that even minimal damage to medial temporal lobes results in significant impairment to autobiographical episodic memory. These findings are more compatible with a memory loss or retrieval deficit rather than a consolidation account of remote memory impairment.

Adult↗
PubMed2000

Information needs and decisional preferences among women with ovarian cancer.

OBJECTIVES: Studies show that women with cancer want more information about and participation in all aspects of their healthcare including decision-making. However, most studies have been done on women with breast cancer, which often runs a lengthy course and has strong patient-advocacy groups. Little is known about the preferences of women with ovarian cancer, the fifth leading cause of cancer death in women, which often has a more rapidly fatal course. METHODS: This study of women with ovarian cancer investigates what information is most vital for women with ovarian cancer, their preferred role in decision-making, and the influence of sociodemographic, disease-related, and psychological factors. RESULTS: Questionnaires were completed by 105 women with ovarian cancer in two Canadian university hospital oncology clinics. Their mean age was 55.8 +/- 14. 9 years. Most were married, well-educated, and considered their health status to be excellent or good, even though over 60% had metastatic disease. Over 80% of these women wanted detailed information about ovarian cancer during the diagnosis, treatment, and posttreatment stages of their disease. In particular, they wanted information pertaining to the disease, treatment, and self-care issues. Approximately 60% of women preferred to share decision-making with their doctors at every stage of the illness. Psychological variables and disease severity were found to influence information needs and decisional preferences. In general, the more psychologically distressed the women, the more information they wanted about coping strategies and the more serious the illness, the more shared decision-making was desired. CONCLUSION: These results present a challenge to health care providers in more adequately meeting the individual information needs of women with ovarian cancer and involving them to the extent that they wish in the decision-making process.

Adult↗
PubMed2000

Men with prostate cancer: influence of psychological factors on informational needs and decision making.

OBJECTIVES: Studies indicate that men with prostate cancer (MPC) adopt passive roles in cancer management; however, increasing public awareness of prostate cancer and advocacy by MPC and their allies suggest otherwise. This study looks at the information that is important to MPC; their preferred participation in decision making; and the influence of sociodemographic, disease, and psychological factors on information needs and decision preferences. METHOD: Consecutive men diagnosed with prostate cancer and attending two tertiary care cancer clinics completed questionnaires on information needs and decision preferences. Questions included demographic information, health and disease status, psychosocial functioning, optimism, and decisional preferences and information preferences for content, type, focus, format, and amount. RESULTS: Questionnaires were completed by 101 MPC. Their mean age was 70 years and most were married and well-educated. Over 70% wanted detailed information at all illness stages focusing on their disease, treatment, survival, self-care, and empowerment. Over 60% of MPC wanted shared decision making with their physician. Psychological variables were found to influence information needs but not involvement in decision making. CONCLUSION: These results represent a challenge to health-care providers for accomodating the informational needs and decision preferences of individual MPC.

Adaptation, Psychological↗
PubMed2000

Material-specific and non-specific attention deficits in children and adolescents following temporal-lobe surgery.

Attentional control in children and adolescents with unilateral temporal-lobe excisions was examined using two experimental tasks, a lexical-decision and a spatial-cue task, and a standardized vigilance task. Participants with left temporal excisions took longer than controls to reorient their attention after invalid cues compared to neutral cues in the lexical task and they made more errors on all three of the tasks. Participants with right temporal excisions differed from controls in the number of errors made on the spatial task. No differences were found between the lesion and control groups on reaction-time measures of the spatial task. The results suggest that a material-specific inhibition impairment, as well as a more general sustained attention deficit, may result after a left temporal excision in childhood or adolescence. These deficits are considered in the context of neuroanatomical models of attentional control.

Adolescent↗
PubMed1994

Alcohol-related dementia in the institutionalized elderly.

This study examined the distribution of alcohol-related and other dementias in a sample of 130 cognitively impaired residents of long-term care facilities in a Northern Ontario community. Study procedures entailed standardized psychiatric, neurological, and neuropsychological evaluations. Diagnoses of dementia of the Alzheimer type (DAT) and vascular dementia were based on criteria of the National Institute of Neurological and Communicative Disorders and Stroke and the Alzheimer's Disease and Related Disorders Association. The diagnosis of alcohol-related dementia (ARD) was based on extensive review of medical history to assess before alcohol abuse and stabilization or improvement in cognitive functioning following institutionalization in conjunction with no other identifiable cause of dementia. ARD comprised 24% of this population compared with DAT (35%), vascular dementia (19%), and other causes (22%). The ARD group was, on average, 10 years younger than the other groups. It had nearly twice the average length of institutionalization and had milder cognitive impairment on both clinical ratings and neuropsychological tests. A diagnosis of ARD was present in the medical records for only 25% of patients in this group. These findings suggest that ARD may be more common than previously suspected in the distribution of dementias in long-term care facilities.

Aged↗
PubMed1991

The frontal cortex and memory for temporal order.

Patients with unilateral frontal- or temporal-lobe excisions and normal control subjects made relative-recency decisions about objects presented sequentially. Several objects within each series were presented in the context of actions to be performed using them, such as "squeeze the sponge", whereas others had only to be named. Both left and right frontal-lobe groups were impaired on order judgements for named items, but their performance was normal for action items. The results suggest that providing salient and distinctive items, involving meaningful actions and multimodal cues, helps compensate for deficits in memory for temporal information associated with frontal-lobe damage.

Adolescent↗
PubMed1987

When priming persists: long-lasting implicit memory for a single episode in amnesic patients.

This experiment investigated the durability of implicit memory for a single episode in normal and amnesic subjects. The target materials consisted of sentence puzzles that were difficult to comprehend in the absence of a key word or phrase. Sentences were re-presented at delays ranging from one minute to one week, and implicit memory was indicated by facilitation in solving previously incomprehensible sentences on subsequent exposures. Patients with severe memory impairments on tests of explicit recall and recognition showed substantial and robust facilitation, or priming, from a single prior presentation and there was no evidence of a systematic decay of facilitation over retention intervals up to one week. The long-lasting implicit memory observed in the sentence puzzle task contrasts with previous findings of rapid decay of priming effects in amnesic patients.

Adult↗
PubMed1981

Semantic priming of lexical decisions in young and old adults.

Twenty-four young (M = 28 years) and 24 old (M = 70 years) adults completed a lexical decision task in which they saw two strings of letters on each trial and were asked to respond "yes" only if both strings were words. For both ages, decisions were faster when the words were associated than when they were not. This pattern emerged for both ages, regardless of whether the associated pairs were category-member or descriptive-property associates. The same participants were also presented with a list of words to free recall. There was a decline with age both in the number of words recalled and in the degree of categorical clustering, particularly of low frequency category exemplars. Viewed from the perspective of two-process semantic activation models, these results place constraints on processing-deficit theories, and are consistent with the hypothesis that effortful processes change with aging, whereas automatic processes do not.

Adult↗
PubMed1980

Semantic activation during memory encoding across the adult life span.

The hypothesis that automatic processes do not change during aging was investigated using Warren's (1972) modification of the Stroop procedure. The subjects were 14 adults in each of three age groups: young (20 to 39), middle (40 to 59), and old (60 to 79). On each trial, subjects held three category members in memory while they named the ink color in which a base item was printed. For all three age groups, color naming latencies were longer when the base item was from the same category as the memory list items. According to network theories of long-term memory, these findings suggest that, throughout adulthood, holding words in working memory results in activation of the memory nodes corresponding to the words themselves, and also in activation spreading to semantically related nodes. The results are consistent with the hypothesis that acquired automatic processes do not deteriorate with aging.

Adult↗