General introduction 25 1 and show a decline (from a previous level), that is, requiring (minimal) assistance with instrumental activities of daily living (IADL)’. These definitions attempt to create a theoretical yes or no situation or a sharp line on the cognitive continuum. However, in clinical practice, there is a grey area, or rather a rainbow, of interpretation differences. Attempts have been made to categorise this continuum. The DSM 5 uses the words ‘modest’ versus ‘substantial cognitive decline from a previous level of performance in one or more of the domains’ to capture the difference between not (yet) having dementia (minor Neurocognitive disorder (NCD)/MCI) and patients with dementia in words. An attempt to operationalize this is by stating ‘test performance in the range of one and two standard deviations below appropriate norms’ for minor versus ‘test performance in the range of two or more standard deviations below appropriate norms’ for major NCD. This translates to a score between the 3rd and 16th percentiles for minor NCD and below the 3rd percentile for major NCD, whereas the (amnestic) MCI was defined to have a delayed recall of 1.5 standard deviations below appropriate norms on a 15-word verbal learning test (Petersen et al., 1999). One method is to quantify the cognitive continuum by using severity or rating scales. The CDR (0-3) (Hughes et al., 1982) and GDS (1-7) (Reisberg et al., 1982) are the most wellknown (Table 3). This is to (try to) objectify the staging of cognitive impairment/dementia and is used for multiple purposes such as research, renewal of the driving licence, and nursing home allocations. Table 3. Rating scales for cognitive impairment. CDR Clinical Dementia Rating Scale GDS Global Deterioration Scale CDR0 No cognitive impairment GDS1 No cognitive impairment GDS2 Age-associated impairment CDR0.5* Very Mild Dementia GDS3 MCI CDR1 Mild Dementia GDS4 Mild Dementia CDR2 Moderate Dementia GDS5 Moderate Dementia CDR3 Severe Dementia GDS6 Moderate Severe Dementia GDS7 Severe Dementia * In clinical practice, CDR0.5 is often considered as equivalent to MCI but formally, it is already called dementia while this is an exclusion criterion for MCI Another factor in dementia diagnostics is to express the diagnostic certainty in terms of probability. This practice of the Alzheimer diagnostic guidelines of the NIA-AA/NINCDSADRDA (McKhann et al., 2011) are spreading to other diagnostic guidelines. The additions
RkJQdWJsaXNoZXIy MTk4NDMw