Objective. To assess selected demographic characteristics (age, gender, education level), clinical variables (cognitive deficit severity, co-morbid cardiovascular disorders) and biochemical parameters (Aβ peptides plasma levels) as potential predictors of amnesic mild cognitive impairment (aMCI) to dementia progression.
Method. An initial cohort of 93 non-demented patients with memory disorders referred to an Outpatient Clinic for Persons with Alzheimer's Disease were examined, and 54 patients with either current somatic disorders or past history that might explain their apparent cognitive deficit were excluded from further study. The remaining 39 patients with aMCI participated in a two-year prospective study: their clinical observation was supplemented with periodic psychometric evaluations using the ADAS-cog, MMSE and CDR. Their plasma levels of Aβ1-40 and Aβ1-42 were measured using the commercially available colorimetric „sandwich" ELISA method.
Results. The aMCI patients who progressed to dementia over the two years, as compared to their clinically stable counterparts, were significantly older (78.5±3.1 vs. 73.0±2.8, respectively, p<0.001); their cognitive dysfunction severity at baseline as measured by the ADAS-cog was more marked (14±2.4 vs. 10.6±1.8, respectively; p<0.01); besides, their ADAS-cog performance was more deteriorated at the 1-year follow-up (4.7 ±1.2 vs. 1.4±2.1, respectively; p<0.01). Additionally, progressors were characterized by lower Aβ1-42 peptide plasma levels (44.7±4.8 vs. 59.2±8.4; p<0.001), and by a lower body mass index (BMI: 26.7±0.5 vs. 27.4±1.0, respectively; p = 0.01). There were no significant differences between the clinically stable and progressing groups with respect to demographic variables such as gender or education level, or the presence of well-controlled cardiovascular disorders.
Conclusions. Older age and higher severity of cognitive dysfunction at baseline (as measured by appropriate psychometric instruments) may be useful predictors of aMCI progression to dementia within two years. Additional factors allowing to assess the risk ofprogression to dementia are lower plasma levels of the Aβ1-42 peptide and lower BMI. However, usefulness of these parameters requires confirmation in larger cohorts. An optimal general medical care, especially in patients with cardiovascular disorders, may be crucial for reducing the risk of dementia development.