Examination of the effect of impairment in attentional processes on other cognitive domains: 6 years follow-up study

Objective: Mild cognitive impairment multiple cognitive domain type (MCI MCDT) is defined as impairment in at least 1 cognitive domain other than memory, or abnormal results in one test of at least 2 separate domains without sufficient severity or loss of activities of daily living (ADLs) to constitute dementia. The aim of this study is to assess whether impaired Digit Span (DS) subtest of Wecshler Memory Scale-Revised (WMS-R), can be alerting for wider decline in other cognitive domains to constitute MCI MCDT in incoming years. Method: We evaluated twenty-eight subjects (9 men and 19 women; mean age 59.7±9.9 with a range of 37 -77 years, mean education 10.0±4.1 with a range of 5 -15 years) with impaired attention in which DS scores were one standard deviation (SD) below of age and education specific standards but preserved memory and executive functions and sixteen subjects (5 men, 11 women, mean age 57.6±8.1 with a range of 44 -69 years, mean education 10.1±4.3 with a range of 5 -15 years) with intact cognitive function in all domains. The neuropsychological evaluation included DS, visual reproduction and associate learning subscales of WMS-R, Verbal Memory Processes Test (SBST), Stroop Test and Category Fluency Test. Both groups were reassessed after 6.6±1.1 years with the same neuropsychological test battery. Wilcoxon test was used to compare re-evaluation of neuropsychological measures in both groups. Results: In longitudinal assessment, compared to normal DS (NSM) group, impaired DS (IDS) group showed significant decreased scores of the highest verbal learning (p=0.001), verbal total learning (p=0.02) and animal list of category verbal fluency (p=0.011). Discussion: Impaired DS scores can predict wider cognitive decline in upcoming years. Also DS seems to be an important immediate step for persons with subjective memory complaint (SMC) converting to MCI-MCDT.Key words: Mild cognitive impairment multiple cognitive domain type; MCI, digit span; neuropsychological assessment; verbal memory; category verbal fluency