Mild cognitive impairment – A hospital-based prospective study

Abstract

Background: Mild cognitive impairment (MCI) is regarded as a transitional state between normal aging and dementia. It may progress to dementia, remain same, or revert to normalcy. Most western studies report an annual conversion of 10%–15% of MCI to dementia. There is a paucity of literature on prospective studies on MCI in India. Objective: The objective is to prospectively study the cognitive status of MCI patients at least 1 year after their diagnosis. The other objective was to find the conversion among the MCI patients to Alzheimer's dementia. Methodology: We followed up persons with MCI above 50 years evaluated in the Geriatric Clinic of National Institute of Mental Health and Neurosciences (NIMHANS) between 2012 and 2014, reassessed their cognitive abilities (neuropsychological measures) 1 year later, and compared them with earlier assessment and the conversion rate among this sample. Hindi Mental Status Examination (HMSE), Everyday Abilities Scale for India (EASI), NIMHANS neuropsychological battery for Indian elderly, and Clinical Dementia Rating (CDR) scale instruments were used for assessment. Results: Twenty-seven persons with a diagnosis of MCI were contacted. Twenty-one participated and underwent repeat clinical and neuropsychological evaluations. The mean duration of follow-up was 1.43 (standard deviation: ± 0.46) years. Six participants (28.6%) had progressed to mild Alzheimer's disease (AD) based on EASI, CDR, and neuropsychological scores, 15 (71.4%) retained their MCI status, and none had reverted back to normal status. The mean age of converters (progressed to mild AD) was 72 ± 5.69 years and nonconverters (remained as MCI) was 72.6 ± 7.16 years. Multiple medical comorbidities were found in both the groups with hypertension being the higher in converters (P = 0.04). Among the converters compared to nonconverters, there was a significant decline in total word list learning (P = 0.006), design construction copy (P = 0.042), total figures canceled in figure cancellation test (P = 0.009), and total omissions on figure cancellation test (P = 0.02). Discussion and Conclusion: Scores on episodic memory, attention, and visuospatial skills were low in the MCI compared to normal controls to start with – there was a further significant decline in few of these parameters over the follow-up. The conversion rate in our study was 28.6% for 1.43 years, which is higher compared to the western studies. Executive function learning and memory were the domains predominantly affected in the converters compared to nonconverters. The study based on tertiary hospital and help seeking with a specialist by those who perceived/were perceived to worsen could be probable reason for this higher rate. Higher medical comorbidities, lower HMSE scores, and executive function and memory at baseline are found to increase the risk of progression to AD.

Keywords

• Dementia
• elderly
• mild cognitive impairment
• neuropsychological measures