Mild cognitive impairment – dementia precursor or normal aging?

Background. Mild cognitive change is common with increasing age and may generate concern. Two stages of mild cognitive changes have been defined; subjective cognitive impairment and mild cognitive impairment (MCI), which is confirmed through cognitive testing. Individuals referred to the Landspítali memory clinic and diagnosed with mild cognitive impairment were invited to participate in the study. The aim of the study was to evaluate the risk of individuals with MCI having a disorder leading to dementia. Material and Methods. 214 individuals diagnosed with mild cognitive impairment from 2014 to 2017, fulfilled the study inclusion criteria and signed an informed consent and participated in the study. Mean age was 72.5 years and mean MMSE score was 27.5 out of a maximum of 30. Results. Of 214 participants diagnosed with MCI at first visit, 73 (34%) were diagnosed with underlying disease causing the symptoms. Following neuropsychological test battery, 26 (12%) did not fulfill diagnostic criteria for mild cognitive impairment, as they did normal cognition on neuropsychological testing, and did not receive further follow-up. Consequently, 115 (54%) were followed up for one year and 79 after two years. At the end of the study, 47 (41%) did still fulfill diagnostic criteria for mild cognitive impairment but two participants had improved their cognitive performance and therefore no longer diagnosed with mild cognitive impairment. Ten participants did not finish the study. Conclusions. One third of participants with diagnosed mild cognitive impairment were diagnosed with underlying disease and a large proportion of participants were furthermore diagnosed with a progressive disease during the study period. Early diagnosis of mild cognitive impairment will be of increasing importance when new disease modifying drugs for common neurodegenerative diseases become accessible.