Summary and general discussion 7 183 4 There must be a recognizable latent or early symptomatic stage of the disease. As mentioned in Chapter 5, cognitive impairment is a continuum where the ‘disease’, as in dementia, or ‘health’ is identified by using classifications. These classifications are on either side of this continuum, creating states that are neither dementia nor ‘without cognitive complaints’. As mentioned in Chapter 1, the criteria for this intermediate state (MCI) are constantly evolving, with a tendency to capture more precise precursors of dementia without including the state of mild impairment due to other aetiologies such as several psychiatric disorders. A frequent mistake is that one considers MCI as a state before dementia in a categorical way, as it were. This mistake is understandable, as MCI increases the probability of converting to dementia substantially. This is even true when the cause is a depression for example. So if we look at MCI as a probability state it is most certainty ‘a recognizable early symptomatic stage’ of ‘being at risk’ to progress on severity and rating scales of cognitive impairment like the CDR and GDS in the near future. Still, experts should become more aware that MCI is not exclusively an early stage of dementia and we hope this theses adds to that. The diagnosis of MCI, when using a screener, is often only based on the (quantitative) cognitive impairment alone, translating to ‘less than dementia’. This phrase almost automatically implies MCI is an ‘early stage of dementia’. Of course a problem is that subjective complaints and informer reports often do not correspond to objective impairment. So without an objective test, it is difficult to recognise MCI, regardless of whether it should be considered a latent stage of dementia. However objective impairment, which is in my opinion not the same as a positive cognitive test, should also incorporate the qualitative component as well, the demographic and clinical characteristics of the patient so to speak. The MoCA fits the task to be this objective test, as it is shown to be reliable, fast, and easy to use. However the MoCA measures only the quantitative part, and it does not incorporate the qualitative part which can add to the differentiation between aetiologies, as an NPA normally would do. The MoCA cannot, as shown in Chapter 4, recognize the latent stage of dementia (MCI-ND) among all MCI’s, as to many cognitive impairment of other aetiologies meet the (quantitative) MCI criteria too. As shown in Chapter 5, using a double threshold, the MoCA can add more differentiation, as MCI patients with a lower MoCA (<21) have a higher probability of conversion to dementia than MCI patients with a higher MoCA score (≥21 MoCA <26). Therefore, if we consider ‘the disease’ as it is used in the criterion 4, being at high risk of (having or getting) severe cognitive impairment, the MoCA can identify MCI, meaning being at risk of conversion, and fulfil the criteria number 4.
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