Screening for and diagnosing dementia in an elderly residential home population : a validation study.
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Date
2014
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Abstract
Background: With the projected increase in the elderly population and expected rise in the
prevalence of dementia, particularly in low-and-middle-income countries, early case identification
is necessary for planning and delivering clinical services. The effectiveness of
dementia screening depends on the availability of suitable screening tools with good
sensitivity and specificity to confidently distinguish normal age-related cognitive decline
from dementia. The aims of this research study were to report on the prevalence of
cognitive impairment (dementia and Mild Cognitive Impairment-MCI), and to assess the
performance of selected screening tools and a neuropsychological battery of tests in a
heterogeneous local population.
Methodology
A cross-sectional study was conducted in a heterogeneous elderly South African population
and consisted of three stages of data collection. In the first stage, cognitive screening
measures were administered to a group of 302 participants, aged +60 years, living in a
residential facility for the aged. The second stage consisted of a sub-sample of 140
participants who were assessed for cognitive impairment based on the Diagnostic and
Statistical Manual of Mental Disorders 4th Edition-Text Revised criteria (DSM-IV-TR). Criteria
A and B for Alzheimer’s and Vascular dementia were applied to assign a diagnosis of
dementia without reference to aetiology. The participants were also assessed for Mild
Cognitive Impairment (MCI), based on the criteria of the International Working Group on
Mild Cognitive Impairment. Of the 140 participants in stage two, 117 were administered a
neuropsychological battery of tests in the third stage. The influence of demographic
variables and the sensitivity, specificity and optimum cut-off scores were determined for the
following seven selected screening measures, individually and in combination: the Mini-
Mental State Examination (MMSE), Subjective Memory Complaint (SMC), Subjective
Memory Complaint Clinical (SMCC), Subjective Memory Rating Scale (SMRS), Deterioration
Cognitive Observee (DECO), Subjective Memory Complaint Clinical (SMCC) and the Clock
Drawing Test (CDT). The sensitivity and specificity of the neuropsychological tests in the
detection of dementia were also determined.
Results
Eleven (7.9%) dementia and 38 (27.1%) MCI cases were diagnosed. Performance on the
screening measures was influenced by race, age and education. Using ROC analyses, the
SMCC, MMSE and CDT were found to be moderately accurate in screening for dementia
with AUC >.70. Neuropsychological test performance was influenced by the age, gender,
race and education level of participants. With the exception of the Digit Span (forward),
Digit Span (total), COWAT-A, Narrative Memory Test (delayed recall), Token Test and the
Luria Hand Sequence Test, all the neuropsychological test measures displayed significance in
distinguishing between the three classification groups (controls, MCI, dementia).
Conclusion
SMCC’s are valid screening questions as a first level of ‘rule-out’ screening. The MMSE can
be included at a second stage of screening at general hospital level and the CDT in specialist
clinical settings. Several measures from the neuropsychological battery of tests evaluated
have discriminant validity and diagnostic accuracy for the differential diagnosis of cognitive
disturbances in an elderly heterogeneous South African population .
Description
Ph. D. University of KwaZulu-Natal, Durban 2014.
Keywords
Dementia., Dementia--Diagnosis., Mild cognitive impairment., Neuropsychological tests., Theses--Psychiatry.