Baseline Predictors of Longitudinal Cognitive Outcomes in Persons with Mild Cognitive Impairment

Abstract

<b><i>Introduction:</i></b> The study aimed to explore longitudinal cognitive outcomes and to ascertain predictors of conversion to dementia in a hospital-based mild cognitive impairment (MCI) cohort classified according to the neuropsychological phenotype at baseline. <b><i>Materials and Methods:</i></b> Subjects aged >55 years who had a clinical diagnosis of MCI at initial visit between 2010 and 2018, with at least one formal neuropsychological assessment at baseline and follow-up of a minimum of 2 years were included. The prospective study was completed based on evaluation at last follow-up to gauge conversion to dementia, quantification of performance on activities of daily living and when available, longitudinal neuropsychological test scores. <b><i>Results:</i></b> Ninety-five patients with MCI met the inclusion criteria with a mean age of 68.4 ± 6.4 years at baseline and a mean duration of follow-up for 6.4 ± 3.2 years. The cumulative conversion rate to dementia was 22.2% (21/95) and the annualized conversion rate was 3.3% per year of follow-up. The majority of subjects who had converted had multidomain MCI (66%). Only white matter changes on MRI brain revealed correlation with baseline neuropsychology tests. The multivariate logistic regression analysis revealed the utility of lower baseline list recognition (adjusted odds ratio: 0.735 [95% confidence interval: 0.589–0.916]; <i>p</i> 0.006), lower immediate logical memory (0.885 [0.790–0.990]; <i>p</i> 0.03), and high perseverative error scores on set shifting (3.116 [1.425–6.817]; <i>p</i> 0.004) as predictors of conversion. A model score of +2.615 could predict conversion with sensitivity of 72% and specificity of 98% over 6.4 years follow-up. <b><i>Conclusion:</i></b> There was a higher risk of conversion associated with multidomain MCI. Logistic regression-based estimations of dementia risk utilizing domain-based neuropsychology test scores in MCI have high specificity for diagnosis at baseline.

Dementia onset among community-dwelling older adults with mild cognitive impairment: A longitudinal study

“…First, the transition rate to dementia is as follows: among 1,375 older adults diagnosed with MCI through an early dementia screening in the community, 83.0% (1,141 people) remained with MCI for 3 years, and 17.0% (234 people) transitioned to dementia. A longitudinal study of cognitive changes over 8 years in older adults with MCI aged 55 years or older enrolled in a dementia clinic in Switzerland [15] reported that 22.2% (n = 21) of 95 individuals transitioned to dementia, which is approximately 5.0% higher than this current study. In South Korea, a study analyzing cognitive changes and influencing factors over a 2-year period in older adults with MCI aged 65 years and older using data from the 6th and 7th KLoSA [8] reported that 21.0% (n = 162) of the 773 subjects transitioned to dementia, which was 4.0% higher than this current study.…”

“…The differences or similarities with our results may be due to the following reasons. First, the time of change in cognitive function in previous studies varied from 1 year [16] to 8 years [15], whereas in this study, dementia transition was tracked for 3 years, which may have affected the transition rate. Second, the diagnostic process of MCI in this study was based on the MMSE-DS; if the sex-, age-, and education-adjusted z-score was less than -1.5 standard deviations from the mean score, the patient was classified as cognitively impaired and was referred to the detailed examination.…”