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Biomedical subjects

E K Warrington

Publications and source records attributed to E K Warrington.

At least 19 recordsLinked to original sources
PubMed1997

Clinicopathological features of familial Alzheimer's disease associated with the M139V mutation in the presenilin 1 gene. Pedigree but not mutation specific age at onset provides evidence for a further genetic factor.

Sixteen affected individuals are described from two families with early onset autosomal dominant familial Alzheimer's disease. A mutation at codon 139 in the presenilin 1 gene on chromosome 14 results in a methionine to valine substitution which cosegregates with the disease in these families. Onset of dementia was before the age of 50 years in all individuals. The ages at onset within each family were tightly clustered but were significantly different between the families; this difference could not be accounted for by apolipoprotein E status and suggests the existence of a further genetic factor that modifies age at disease onset. The pattern of cognitive decline was similar in both families: early memory loss (initially selective for verbal memory in some individuals) was followed soon after by loss of arithmetic skills while naming and object perception skills were relatively preserved. A speech production deficit was observed in three members of one family but not in the other. Seizures were common and usually predated by myoclonic jerks by a number of years. Serial MRIs showed progressive cortical atrophy with periventricular white matter change appearing 3-4 years into the disease. PET revealed parieto-temporal hypometabolism in all individuals scanned. The diagnosis of Alzheimer's disease was confirmed with typical histopathology in one individual from each family.

Adult↗
PubMed1997

The abstraction of numerical relations: a role for the right hemisphere in arithmetic?

Arithmetical reasoning ability has been investigated in a group study of patients with unilateral cerebral lesions. Two series of 38 and 39 patients, who had suffered unilateral cerebral lesions of the right and left cerebral hemisphere, respectively, were investigated. They completed a neuropsychological battery that included a test of computation (Graded Difficulty Arithmetic, GDA; Jackson & Warrington, 1986), and a new test of numerical series completion (Arithmetical Reasoning Test, ART). Whereas the left-hemisphere lesion group were markedly more impaired on the GDA compared to both the right-hemisphere lesion group and a standardization sample, both lesion groups were equally severely impaired on the ART. It is suggested that the abstraction of numerical relations, which is essential to numerical series completion, relies on the integrity of the right hemisphere. A global model of arithmetic processing that incorporates these findings is proposed.

Adult↗
PubMed1996

Studies of retrograde memory: a long-term view.

Studies of retrograde amnesia are reviewed. First, the issues of temporal gradients of retrograde amnesia are discussed. Second, the question of the anatomical substrates of this syndrome are considered. Finally, some evidence for fractionation of different classes of memoranda within the retrograde time period are presented.

Aged↗
PubMed1996

Atrophy of the hippocampal formation in early familial Alzheimer's disease. A longitudinal MRI study of at-risk members of a family with an amyloid precursor protein 717Val-Gly mutation.

The hippocampal formation (HF) is known from pathological and magnetic resonance imaging (MRI) studies to become severely atrophied in established Alzheimer's disease (AD). This study examined whether changes in the HF could also be detected in very early AD by scanning subjects at risk of developing familial AD (FAD). Five at risk members of a pedigree with the amyloid precursor protein (APP) 717 valine to glycine mutation underwent serial MRI scanning with volumetric measurement of the HF as well as neurological and neuropsychological assessments. Over a period of two years two subjects became clinically affected, a loss of up to 20% of the volume of the HF occurred in the two years over which symptoms first appeared. Asymmetrical HF atrophy was shown to have been present before the development of overt symptoms. This may have important implications for early diagnosis in AD more generally.

Adult↗
PubMed1996

Does recognizing orally spelled words depend on reading? An investigation into a case of better written than oral spelling.

In this study we describe an investigation into the residual spelling skills of a patient (BRK) with a deep dysgraphia. His written spelling was significantly superior to his oral spelling and he had grave difficulties in recognizing orally spelled words. In addition, his impairment in recognizing orally spelled words was qualitatively very similar to his difficulties in oral spelling. In contrast, he could read and repeat the stimuli he could no longer spell. It seems therefore that, recognizing orally spelled words is dependent on the same procedures used in spelling rather than in reading. It is argued that BRK's discrepancy between oral and written spelling reflects a deficit in accessing a letter name code which translates abstract graphemic representations into letter names. In addition, it is suggested that the letter name code has an additional synthesizing function that is involved both in checking self-generated oral spellings and in recognizing orally spelled words.

Aphasia, Wernicke↗
PubMed1996

Two routes to naming: a case study.

We report the case of an aphasic patient, KP, whose spontaneous speech and ability to communicate verbally were severely reduced. His comprehension of written words was preserved. Naming was relatively preserved for objects but impaired for actions. We designed experiments to investigate his verb processing and sentence completion. KP's knowledge of verb syntax was impaired in contrast to his relatively preserved knowledge of verb semantics. His ability to retrieve a noun on visual confrontation was significantly better than his ability to retrieve the same pool of nouns through propositional language. We interpret the data in terms of two 'routes' to noun-retrieval, a nominal route and a propositional speech route. Furthermore, we suggest that the dissociation between verb syntax and verb semantics can also be accounted for within this framework.

Aged↗
PubMed1996

Spared retrograde memory with anterograde amnesia and widespread cognitive deficits.

A case is described of a young male who suffered head injuries in a motor accident and subsequently displayed a severe anterograde amnesia in the presence of a relatively intact retrograde memory. He also demonstrated marked impairment of general intellectual ability, naming, perceptual skills and executive functioning. This case demonstrates a striking dissociation between anterograde and retrograde memory. Moreover the retention of retrograde memory in the face of such severe and global cognitive impairment accentuates the dissociation or isolability of retrograde memory. It is further argued that while frontal impairment occurred in this case it lacks any of the hallmarks of frontal amnesia. The case is further evidence for the fractionation of amnesic syndromes.

Adult↗
PubMed1996

Topographical disorientation: selective impairment of locomotor space?

We report a single-case study of a patient who suddenly lost her ability to orient herself in her neighbourhood. On formal testing she demonstrated remarkably selective deficits in episodic and semantic memory of topographical items and rouse. Her general intellectual abilities were unaffected as were basic perceptual processes and episodic and semantic memory other than topography. We interpret her deficit as a further example of category-specific processing impairment affecting knowledge acquired through selective channels-in this case visuo-locomotor information.

Brain↗
PubMed1996

Short-term memory impairment and arithmetical ability.

We document the dissociation of preserved calculation skills in a patient with impaired auditory short-term memory. The patient (MRF) had a memory span of three digits. Furthermore, he showed rapid decrement in performance of single digits and letters with both auditory and visual presentation in the Brown-Peterson forgetting task. Analysis of his calculation skills revealed a normal ability to solve auditorily presented multidigit addition and subtraction problems such as 173 + 68 and to execute the Paced Auditory Serial Addition Task (Sampson, 1956, 1958; Gronwall, 1977). In addition, his performance on other tests, including arithmetic manipulation of natural numbers, decimals and fractions, approximation, magnitude, ratio, and percentage, appeared to be normal (Hitch, 1978b). It is argued that these findings require a revision of Baddeley and Hitch's (1974) concept of the function of working memory.

Amnesia↗
PubMed1996

Word comprehension. The distinction between refractory and storage impairments.

We report a series of experiments in which we compare the residual word comprehension skills of patients with cortical degenerative conditions and those with an "access' dysphasia. Using word-picture matching tasks it was shown that (i) the presentation rate (the response-stimulus interval) affected the word comprehension performance of the patients with an access dysphasia but not of the patients with degenerative conditions; (ii) the semantic relatedness of the stimulus arrays had a greater influence in the performance of the access dysphasic patients than with a degenerative condition; (iii) word frequency was a strong determinant of the performance of patients with degenerative conditions but not those with an access dysphasia; and (iv) response inconsistency was a characteristic of the patients with an access dysphasia, whereas this was not observed in those with a degenerative condition. These four effects clearly differentiate the word comprehension performance of these two types of patients. Thus, two types of word comprehension impairment have been identified. A unitary account of the pattern of performance in the access patients in terms of refractoriness has previously been proposed and it is reiterated here. Similarly, a unitary account of the patients with degenerative conditions in terms of storage deficit is advanced. It is speculated that these two types of deficit, refractoriness and storage, reflect two sources of damage to the stored representations underpinning a word, rather than a dichotomy between deficits affecting the procedures of accessing semantic representations and the stored representations themselves. The implications for neurological diagnosis and therapeutic intervention are discussed.

Aged↗
PubMed1996

Presymptomatic hippocampal atrophy in Alzheimer's disease. A longitudinal MRI study.

The hippocampal formation (HF) is known from pathological and MRI studies to be severely atrophied in established Alzheimer's disease. However, it is unclear when the earliest changes in the HF occur. We performed a longitudinal study of asymptomatic individuals at risk of autosomal dominant familial Alzheimer's disease in order to assess presymptomatic changes in the HF. Seven at risk members of a familial Alzheimer's disease pedigree associated with the amyloid precursor protein 717 valine to glycine mutation underwent serial MR scanning and neuropsychological assessments over 3 years. These assessments were compared with results from 38 normal controls. During the study three at risk subjects became clinically affected. Volumetric measurement of the HF showed that asymmetrical atrophy developed in these subjects before the appearance of symptoms. Verbal and visual memory measures declined in parallel with hippocampal loss. A loss of up to 8% per annum of the volume of the HF occurred in the 2 years over which symptoms first appeared. These findings may have implications for early diagnosis of Alzheimer's disease.

Aged↗
PubMed1995

The isolation of calculation skills.

The unusual preservation of calculation skills in a patient with severe global aphasia is described. The implications for the relationship between numerical and language abilities are discussed.

Aphasia↗
PubMed1995

Impaired naming and preserved reading: a complete dissociation.

This study examines the relationship between reading and naming in an anomic patient whose verbal comprehension skills were intact. In spite of very poor naming skills, his ability to read irregular words was well preserved. Moreover, his naming remained impaired in conditions when he had read the same word only a few minutes or even seconds before and there was unexpectedly little overlap between his performance on the two tasks. The implications of these results for current models of reading and naming are discussed.

Adult↗
PubMed1995

Selective impairment in manipulating Arabic numerals.

This paper describes an acalculic patient (B.A.L.) with an unusual selective deficit in manipulating arabic numerals. The patient was unimpaired in reading aloud letters, words and written number names but unable to read aloud single arabic numerals. Furthermore, his ability to produce the next number in the sequence and his ability to produce answers to simple addition and subtraction was relatively spared when the stimuli were presented as number names but impaired when the stimuli were presented as arabic numerals. Using magnitude comparison tasks it was demonstrated that his knowledge of cardinal values of arabic numerals was preserved. His impairment in manipulating arabic numerals was interpreted in terms of a deficit in the connection between format specific number codes and the verbal numeral production system.

Agraphia↗
PubMed1995

Word specific impairments in naming and spelling but not reading.

A patient, who had suffered a left-hemisphere CVA, is described. He had a major aphasic syndrome which encompassed both his propositional speech and literacy skills. However, his comprehension of both spoken and written language was intact. His superior ability to retrieve nouns as opposed to other word classes was systematically investigated. This superiority of noun processing was restricted to concrete nouns. It was found that he had a significant deficit in the naming of action pictures as compared with object pictures, and a significant deficit in the written spelling of verbs as compared with nouns when matched for concreteness. His single-word reading, for all word classes, was virtually intact. The theoretical significance of these findings is discussed. It is concluded that current information processing models, that postulate a unitary phonological output store, will require elaboration in order to account for these data. We tentatively suggest that there may be exclusive output stores for naming, reading and spelling.

Aphasia↗
PubMed1995

Semantic memory and reading abilities: a case report.

We document the unexpected dissociation of preserved reading skills in a patient with severely impaired semantic memory. The common co-occurrence between impairment of word meaning and surface dyslexia has not been observed. The patient (hereafter called DRN) had marked naming and word comprehension difficulties. A strong word frequency effect was observed on tests of word comprehension but was absent in a test of word reading. DRN's ability to read both regular and exception words that he failed to comprehend was remarkably well preserved. We will argue that these findings provide further support for the independence of semantic and phonological processing.

Aged↗
PubMed1995

A longitudinal study of reading ability in patients suffering from dementia.

The aim of this study was to investigate whether reading is a preserved ability in patients suffering from dementia, as was first suggested by Nelson and McKenna (1975). The 57 patients included in the study had possible or probable Alzheimer's disease or similar degenerative conditions and were assessed longitudinally. Their performance on the National Adult Reading Test [(NART); Nelson, 1982, 1991] is compared to that on a shortened version of the WAIS-R. It is found that although performance on the NART does decline gradually over time, the deterioration on formal tests of IQ is more rapid and more severe. It seems that the decline in reading across the group is due to those patients who have a lower verbal IQ (VIQ) than performance IQ (PIQ). It is concluded that generally the NART can be used as a predictor of the premorbid intellectual functioning of a patient with dementia, given that the VIQ is greater than PIQ.

Adult↗