Basal Serum Cortisol Levels, Depression And Medial Temporal Lobe Atrophy In Patients With Mild Cognitive Impairment And Alzheimer’s Disease

Objectives: Changes in serum cortisol levels have been reported in Alzheimer's disease (AD) and Mild Cognitive Impairment (MCI). Atrophy of Medial Temporal Lobes (MTLs) is common in both conditions. Glucocorticoids are known to be neurotoxic and have been believed to cause damage to memory mechanisms in the brains; whether the same is applicable to AD/MCI is not known. Also, they have long been hypothesized to cause atrophy of MTLs but the proof of the same is lacking. The present study was performed to delineate correlations between serum Cortisol levels, Depression in Dementia and Medial Temporal Lobe Atrophy in patients with AD/MCI. Methods: We randomly recruited 28 patients out of a total of 65 presenting with subjective memory complaints to the Department of Neurology, at a tertiary care institute during the study period (July 2014-2015). Morning serum Cortisol levels (8 AM) were analyzed in all patients (n=28) who met the diagnostic criteria for diagnosis of probable AD e.g. National Institute of Neurological and Communicative Disorders and Stroke, Alzheimer's disease related Disease Association criteria (NINCDS-ARDA) and Clinical Dementia Rating (CDR) for AD and MCI respectively. The Cornell Scale for Depression in Dementia (CSDD) was used to evaluate Depression. Visual Rating of Medial Temporal Lobe Atrophy (MTLA) was done using the Scheltens Visual Rating Scale. An association between the Depression and MTLA was evaluated using Pearson correlation coefficient. Results: A total of 28 Patients (M: F=24:4, AD=13, MCI=15) were recruited for the present study. The mean age was 73.39 ±7.6 years and mean duration of illness was 3.4±3 years. Mean Mini Mental State Examination (MMSE) score was 21.7±7.4. A total of 4 patients (14%) had a high basal serum cortisol. Only one case out of these 4 had MCI and the rest had AD. There was a statistically significant correlation between serum Cortisol levels and MTLA (Pearson Correlation Coefficient=0.39, p<0.05). Similarly, a statistically significant correlation was found between serum Cortisol levels and CSDD scores (Pearson Correlation Coefficient=0.49, p<0.05). Likewise, there was a statistically significant negative correlation between MMSE and CSDD (Pearson Correlation Coefficient=-0.48, p<0.001). Conclusion : Statistically significant correlation between Serum Cortisol and MTA Scores as assessed by Scheltens Visual Rating Scores was found (Pearson Correlation Coefficient=0.39, p<0.05; 95% confidence interval=0.02 to 0.66). Similarly, a significantly correlation was present between serum cortisol and CSDD Scores (Pearson Correlation Coefficient=0.49, p<0.05; 95% confidence interval=0.144 to 0.729). This suggests that glucorticoids and depression and MTA in AD/MCI are inter-related and points towards the possible role that increase in endogenous glucocorticoids may play in pathophysiol-ogy of AD/MCI.