ementia has as its central feature impairment incognitive function. Clinically, the cognitive
deficit willmost often manifest itself as memory problems and mostusually as difficulties in the ability to retain new
infor-mation. However, a number of other areas of
cognitionare affected and it is important to realize that memory
isbut one of the cognitive skills compromised in dementia.Dementia is thus prima facie a disorder of cognition
andit is our cognitive facilities that underlie our abilities
toengage successfully in the activities of daily living
(ADL).From this it follows that enhancement to cognitive func-tion will facilitate performance of these ADL.The assess-ment and understanding of these impairments are crucialto any treatment of the disorder.Behavioral observation today has a very limited role
toplay in the assessment of mental ability, as it
is now knownthat many important aspects of cognitive function are
notreadily assessable by this technique. Cognition
can onlytruly be assessed accurately through the direct use
ofobjective psychometric tests. However, historically
thediagnosis of dementia has been largely the province
ofgerontologists and old-age psychiatrists, who, in the7 7C l i n i c a l r e s e a r c hThe evaluation of cognitive function
in thedementias: methodological and
regulatoryconsiderationsKeith A. Wesnes, PhD; John
E. Harrison, PhDKeywords: cognitive
testing; automated testing; cognitive function; dementia; Alzheimer’s
disease; dementia
with Lewy bodiesAuthor affiliations: Cognitive Drug Research Ltd, Reading, UK (Keith A. Wesnes); Human Cognitive Neuroscience Unit, Northumbria University,
Newcastle upon Tyne, UK (Keith A. Wesnes); Cambridge Psychometric
Consultants, Warminster, Wilts, UK
(John E. Harrison)Address for correspondence: Keith A. Wesnes, PhD, Cognitive Drug Research
Ltd, Portman Road, Reading
RG30 1EA, UK
(e-mail: Keithw@cdr.org.uk)Impairment of cognitive function is
the central feature of dementia. Although, clinically, the cognitive deficit
mostoften manifests itself as memory problems,
a number of other areas of cognition are affected, and memory is butone of the cognitive skills compromised
in dementia. Dementia with Lewy bodies, for example, accounts for 15% to25% of all dementias and does not
have memory deficits as a core feature. Our cognitive facilities underlie our
abil-ities to engage successfully in the
activities of daily living (ADL) and it follows that enhancement of cognitive
func-tion will facilitate performance of
ADL. The assessment and understanding of these impairments are crucial to anytreatment of the disorder. Unfortunately,
the principal instrument used to assess cognitive function in most of themajor clinical trials of Alzheimer’s
disease in recent years, the Alzheimer’s Disease Assessment Scale–CognitiveSubsection (ADAS-COG), primarily
assesses aspects of memory, which has resulted in other important cognitive deficitsin dementia being overlooked. Automated
cognitive tests are now available that can identify an earlier onset ofimprovements in dementia in smaller
samples than the ADAS. Regulatory authorities should encourage—or evenrequire—the use of automated
procedures alongside the ADAS in pivotal trials to help determine the relative
util-ity of the instruments in the fairest
way possible. Whatever the outcome, this will be of long-term benefit to patients,carers, drug developers, clinicians,
and regulators in this important area.Dialogues Clin Neurosci.
2003;5:77-88.D
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