The Goteborg MCI study: mild cognitive impairment is a heterogeneous condition
- 1Sahlgrenska Academy, Institute of Clinical Neuroscience, Göteborg University, Göteborg, Sweden
- 2Sahlgrenska University Hospital, Neuropsychiatric Clinic, Molndal, Sweden
- 3Department of Psychology, Göteborg University
- Correspondence to: Arto Nordlund Sahlgrenska Academy, Institute of Clinical Neuroscience, Sahlgrenska University Hospital/Mölndal, SE 431 80 Mölndal, Sweden; arto.nordlundneuro.gu.se
- Received 21 July 2004
- Accepted 14 February 2005
- Revised 28 January 2005
Abstract
Background: Mild cognitive impairment (MCI) has been considered a transitional state between normal aging and dementia, characterised by memory impairment but normal general cognitive functioning. Recently other cognitive deficits have been reported. This has led to a modification of MCI criteria.
Objective: To examine which neuropsychological tests most clearly distinguish MCI subjects from normal controls.
Methods: 112 consecutive MCI subjects and 35 controls were included in the study. The diagnosis of MCI was based on an objective history of cognitive decline and a neuropsychiatric examination, comprising instruments STEP, I-Flex, MMSE, and CDR. Participants were examined with 21 neuropsychological tests in the cognitive domains speed/attention, memory and learning, visuospatial function, language, and executive function.
Results: Controls were significantly older. No differences were found in education or general intellectual capacity. Controls performed significantly better than MCI on tests within all five cognitive domains. The clearest differences were seen on language tests, followed by executive function, and learning and memory. Only two subjects (1.8%) were purely amnestic; 17% showed no impairment compared with controls, with a cut off of 1.5 SD below age mean. These subjects were better educated and performed significantly better on measures of general cognitive capacity.
Conclusions: The results illustrate the heterogeneity of MCI, with a significant degree of impairment in all five cognitive domains. When examined with a comprehensive neuropsychological battery, very few subjects had an isolated memory impairment.
- AACD, aging associated cognitive decline
- AAMI, aging associated memory impairment
- AAN, American Academy of Neurology
- ASLD, assessment of subtle language disorders
- CDR, clinical dementia rating
- GDS, global deterioration scale
- I-Flex, short form of the executive interview (EXIT) test
- MCI, mild cognitive impairment
- MMSE, mini-mental state examination
- PaSMO, parallel serial mental operations
- PCA, principal components analysis
- RAVLT, Rey auditory verbal learning test
- RCF, Rey complex figure test
- STEP, stepwise comparative status analysis
- VOSP, visual object and space perception
- WCST, Wisconsin card sorting test
- WLM, Wechsler’s logical memory test
Footnotes
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Competing interests: none declared
