Medical News

Overview

Gastroenterology

Gynaecology

Endocrinology

Others

The article below is extracted from Medical Tribune dated 15 - 31 Dec 2006. You can download the issue from Medical Tribune website at http://www.medicaltribune.com/

Mild cognitive impairment (MCI) is a transitional stage between normal aging and dementia, and is a high-risk condition for the development of Alzheimer’s disease (AD).1 In contrast to dementia, although people with MCI appear to have memory problems, they do not experience significant impairment in social or occupational functioning.

Heterogeneity of MCI

MCI is a heterogeneous condition due to numerous different causes, which may overlap in individual patients. There are 3 subtypes of MCI:

• Amnestic MCI

  The single domain affected is memory. Amnestic MCI generally represents the early stage of AD.2 Numerous studies have documented the progression to dementia and AD in MCI subjects. 3-5

• Multiple-domain MCI

  A person with multiple-domain MCI may have impairments in several cognitive domains (e.g.: judgment, language), with or without memory impairment. It usually progresses into AD or vascular dementia. Although multiple-domain MCI is most predictive of dementia, 6 it is not always a predictor of AD.7 Additionally, this form of MCI may also be associated with neuropsychiatric disorders, such as depression and personality changes.

• Single non-memory MCI

  A person with single non-memory MCI has impairment in a non-memory area (e.g.: executive function, language). The other cognitive domains, including memory, are essentially normal. This form of MCI evolves frequently into other dementing illnesses, such as frontotemporal dementia and Lewy-body dementia.

Diagnosis of MCI

Although it is difficult to precisely diagnose the cause of MCI due to the possibilities of neuropsychological profiles overlapping, a comprehensive work-up and more specific biological markers of MCI are required to help distinguish the underlying pathologies of dementia. Potentially useful markers include functional and structural abnormalities found on imaging studies (e.g.: hippocampal atrophy) 8,9 and putative biochemical markers (e.g.: cerebrospinal fluid biomarkers). 10 Neurophysiology tests (e.g.: quantitative electroencephalography) may also help improve the diagnosis of MCI.11

Memory complaints and dementia

Population studies show that new subjective memory complaints in elderly are highly predictive of dementia. 12 Although memory complaints are not always related to impaired memory performance, non-demented elderly subjects with MCI tend to have more frequent memory complaints than those without MCI. 13 Memory performance is also lower in non-demented subjects that have memory complaints. 14 Therefore, it is still important to perform memory tests in subjects with memory complaints.

References:
1. Peterson RC, et al. Arch Neurol 2001;58:1985-1992
2. Storandt M, et al. Neurology 2006;67:467-473.
3. Bennett DA, et al. Neurology 2002;59:198-205.
4. Morris JC, et al. Arch Neurol2001;58:397-405.
5. Jicha GA, et al. Arch Neurol 2006;63:674-681.
6. Busse A, et al. Psychol Med 2003;33:1029-1038.
7. DeCarli C. Lancet Neurol 2003;2:15-21.
8. Singh V, et al. Brain 2006; [Epub ahead of print].
9. Machulda MM, et al. Neurology 2003;61:500-506.
10. Blennow K. NeuroRX 2004;1:213-225.
11. Sneddon R, et al. Clin EEG Neurosci 2005;36:141-150.
12. Schofield PW, et al. Arch Neurol 1997;54:7560759.
13. Bassett SS, Folstein MF. J Geriatr Psychiatry Neurol 1993;6:105-111.
14. Jonker C, et al. J Am Geriatr Soc 1996;44-49.