Specificity of Cognitive Impairment in Neurological Disease: A Methodological Critique of Parkinson’s Disease

Multiple cognitive deficits have been recognized in many neurological disorders but the specificity of the findings and the relationship to the underlying neuropathology remain obscure. Definitions of dementia have been proposed based on symptom profiles of the cognitive disorder and qualitative dif...

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Main Author: H. J. Sagar
Format: Article
Language:English
Published: Wiley 1991-01-01
Series:Behavioural Neurology
Online Access:http://dx.doi.org/10.3233/BEN-1991-4205
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author H. J. Sagar
author_facet H. J. Sagar
author_sort H. J. Sagar
collection DOAJ
description Multiple cognitive deficits have been recognized in many neurological disorders but the specificity of the findings and the relationship to the underlying neuropathology remain obscure. Definitions of dementia have been proposed based on symptom profiles of the cognitive disorder and qualitative differences have been claimed between dementias of different aetiology. Some conditions have been claimed to show patterns of cognitive deficit that are distinguished from dementia and related to specific neuropathology or psychological processes, e.g. frontal lobe deficits in Parkinson's disease. Sometimes, a relationship has been established between certain cognitive deficits and particular neurochemical deficits which has led to the notion of specific drug treatment, e.g. cholinergic deficits and memory failure in Alzheimer's disease. However, these conclusions are often potentially flawed by methodological inadequacies. This critique presents some methodological issues relevant to the study of brain-behaviour and drug-behaviour relationships in syndromes of multiple cognitive deficit, using Parkinson's disease as the model. The following recommendations are made: rigid diagnostic criteria; representative patient groups; avoidance of arbitrary quantitative criteria to limit definitions of dementia; matching of groups for overall level of cognitive impairment in the search for qualitative cognitive differences related to neuropathology or effects of particular drugs; the use of suitable controls in patient groups, neuropsychological tests and treatment regimes; the use of specific quantitative tests of cognition, affect and motor disability; and longitudinal, compared with cross-sectional, study design.
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spelling doaj-art-8b1973e0110b42f0b49c05812fb2066a2025-02-03T05:45:40ZengWileyBehavioural Neurology0953-41801875-85841991-01-01428910210.3233/BEN-1991-4205Specificity of Cognitive Impairment in Neurological Disease: A Methodological Critique of Parkinson’s DiseaseH. J. Sagar0Department of Neurology, Royal Hallamshire Hospital, Sheffield S10 2JF, Yorkshire, UKMultiple cognitive deficits have been recognized in many neurological disorders but the specificity of the findings and the relationship to the underlying neuropathology remain obscure. Definitions of dementia have been proposed based on symptom profiles of the cognitive disorder and qualitative differences have been claimed between dementias of different aetiology. Some conditions have been claimed to show patterns of cognitive deficit that are distinguished from dementia and related to specific neuropathology or psychological processes, e.g. frontal lobe deficits in Parkinson's disease. Sometimes, a relationship has been established between certain cognitive deficits and particular neurochemical deficits which has led to the notion of specific drug treatment, e.g. cholinergic deficits and memory failure in Alzheimer's disease. However, these conclusions are often potentially flawed by methodological inadequacies. This critique presents some methodological issues relevant to the study of brain-behaviour and drug-behaviour relationships in syndromes of multiple cognitive deficit, using Parkinson's disease as the model. The following recommendations are made: rigid diagnostic criteria; representative patient groups; avoidance of arbitrary quantitative criteria to limit definitions of dementia; matching of groups for overall level of cognitive impairment in the search for qualitative cognitive differences related to neuropathology or effects of particular drugs; the use of suitable controls in patient groups, neuropsychological tests and treatment regimes; the use of specific quantitative tests of cognition, affect and motor disability; and longitudinal, compared with cross-sectional, study design.http://dx.doi.org/10.3233/BEN-1991-4205
spellingShingle H. J. Sagar
Specificity of Cognitive Impairment in Neurological Disease: A Methodological Critique of Parkinson’s Disease
Behavioural Neurology
title Specificity of Cognitive Impairment in Neurological Disease: A Methodological Critique of Parkinson’s Disease
title_full Specificity of Cognitive Impairment in Neurological Disease: A Methodological Critique of Parkinson’s Disease
title_fullStr Specificity of Cognitive Impairment in Neurological Disease: A Methodological Critique of Parkinson’s Disease
title_full_unstemmed Specificity of Cognitive Impairment in Neurological Disease: A Methodological Critique of Parkinson’s Disease
title_short Specificity of Cognitive Impairment in Neurological Disease: A Methodological Critique of Parkinson’s Disease
title_sort specificity of cognitive impairment in neurological disease a methodological critique of parkinson s disease
url http://dx.doi.org/10.3233/BEN-1991-4205
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