Study Of The Relationship Between Serum Cortisol And Dehydroepiandrosterone Sulfate (DHEAS) Levels And Degree Of Cognitive Impairment In The Aged With Alzheimer's Disease And Vascular Dementia

Abstract

Background: Dementia is the general term that refers to the decline of mental abilities including memory and other thinking skills while a person is alert and awake. Dementia is considered a late-life disease because it tends to develop mostly in elderly people. The two most common forms of dementia in older people are Alzheimer’s disease and multi-infarct dementia (vascular dementia). Alzheimer's disease accounts for around 60 % of all cases of dementia, while vascular dementia accounts for up to 20 % of all cases of dementia. Cortisol and dehydroepiandrosterone (DHEA) and its sulfate ester (DHEAS) are adrenal steroid hormones. These hormones have been suggested to have a role in many aging related diseases and perhaps in aging itself. These hormones have been shown to multiple effects on the function of the hippocampus, which is involved in learning and memory processes. These adrenal steroids may thus be associated with cognitive impairment, which is a major symptom of dementia.

Objectives: To study the relationship between serum cortisol and dehydroepiandroesterone sulfate (DHEAS) levels and degree of cognitive impairment in the aged persons with Alzheimer's disease and vascular dementia.

Methods: Study was conducted on 30 elderly demented patients selected randomly from the general population. Their ages ranged from 52 to 85 years with a mean of 68.5 years and they were 13 males and 17 females, they were divided into two groups; group I: 15 patients (7 males and 8 females) with probable Alzheimer's disease diagnosed according to diagnostic and statistical manual of mental disorder (DSM- IV criteria), group II: 15 patients (6 males and 9 females) with vascular dementia, group III consisted of 15 elderly healthy volunteers, matched for age and sex with no evidence of dementia have been served as control group. All were submitted to morning collection of blood for determination of the plasma cortisol and DHEAS measured by chemiilluminescence. The 30 points Mini Mental State Examination (MMSE) was used to assess cognition.

Results: The present study firstly showed that mean serum cortisol level increase while mean serum DHEAS
level decrease with age and mean serum cortisol levels was higher in both AD  and VD than normal controls
while mean serum DHEAS levels in both AD and VD) was lower than normal controls. Gender did not
play a significant role in variability of cortisol and DHEAS. Also, most of Alzheimer's disease patients were none educated in comparison to vascular dementia patients and this indicates that a low level of education has been associated with a greater risk of developing AD. There is an association between serum cortisol and DHEAS levels and severity and duration of dementia and cognitive decline in demented patients.

Conclusion: There is a strong association between cortisol and DHEAS and prevalence of dementia in the elderly. There was a trend of high serum cortisol level in males and high serum DHEAS level in females but, gender did not play a significant role in variability of cortisol and DHEAS. Low level of education has been associated with a greater risk of developing dementia and there is association between serum cortisol and serum DHEAS levels and duration and severity of dementia.