Salivary Cortisol and Memory Function

Researchers writing in the medical journal Neurobiology of Aging say their “results partially confirm previous findings that high cortisol is associated with impaired declarative memory function in non-demented older persons. In addition, our data show that high salivary cortisol concentrations predict a decline in memory function over the next 3 years.”

From the study abstract
Li G, Cherrier MM, Tsuang DW, Petrie EC, Colasurdo EA, Craft S, Schellenberg GD, Peskind ER, Raskind MA, Wilkinson CW. Salivary cortisol and memory function in human aging. Neurobiol Aging. 2006 Nov;27(11):1705-14. Epub 2005 Nov 4

OBJECTIVE: To examine the association of salivary cortisol with cognitive changes in a 3 year longitudinal study. Previous studies have suggested that elevated glucocorticoid concentrations alter hippocampal neuronal morphology, inhibit neurogenesis, and impair cognition.

METHODS: Salivary cortisol samples were collected at home by 79 cognitively intact older persons (mean age 78+/-7 years) at 08:00, 15:00 and 23:00h, and collections were repeated annually for 3 years. Cognitive function was also assessed annually.

RESULTS: The mean cortisol level of samples taken at three times of day and the cortisol concentration at 23:00h were significantly associated with poorer performance on tasks of declarative memory and executive function. Of 46 subjects who completed the entire 3 year study, higher initial cortisol concentration at 23:00h predicted a decline in performance of delayed paragraph recall.

CONCLUSION: These results partially confirm previous findings that high cortisol is associated with impaired declarative memory function in non-demented older persons. In addition, our data show that high salivary cortisol concentrations predict a decline in memory function over the next 3 years.

Alzheimer’s Disease Research

Insulin and Aging
A new study, to be published, says that high insulin levels, among both diabetics and non-diabetics, may contribute to Alzheimer’s disease.

To quote the authors of the study “Although this model has obvious relevance for diabetes mellitus, hyperinsulinemia and insulin resistance are widespread conditions that affect many nondiabetic adults with obesity, impaired glucose tolerance, cardiovascular disease, and hypertension. Our results provide a cautionary note for the current epidemic of such conditions, which, in the context of an aging population, may provoke a dramatic increase in the prevalence of AD (Alzheimer’s).”

You can read the entire article at the Journal of Neurology

Obesity and vascular risk factors at midlife and the risk of dementia and Alzheimer disease.
Kivipelto M, Ngandu T, Fratiglioni L, Viitanen M, Kareholt I, Winblad B, Helkala EL, Tuomilehto J, Soininen H, Nissinen A. Arch Neurol. 2005 Oct;62(10):1556-60.

From the abstract: “Obesity at midlife is associated with an increased risk of dementia and AD (Alzheimer’s Disease) later in life. Clustering of vascular risk factors increases the risk in an additive manner. The role of weight reduction for the prevention of dementia needs to be further investigated.”
Read the abstract

Brain Estrogen Deficiency and Alzheimer’s Disease
Writing in the Proceedings of the National Academy of Sciences (USA), researchers studied the effects of estrogen deficiency and Alzheimer’s Disease. They wrote: “Much evidence indicates that women have a higher risk of developing Alzheimer’s disease (AD) than do men. The reason for this gender difference is unclear. We hypothesize that estrogen deficiency in the brains of women with AD may be a key risk factor….Our results indicate that estrogen depletion in the brain may be a significant risk factor for developing AD neuropathology.”

Yue X, Lu M, Lancaster T, Cao P, Honda SI, Staufenbiel M, Harada N, Zhenyu Z, Shen Y, Rena Li R Brain estrogen deficiency accelerates Aβ plaque formation in an Alzheimer’s disease animal model Proc. Natl. Acad. Sci. USA, 10.1073/pnas.0505203102

Melatonin and Alzheimer-like neurodegeneration
Writing in the medical journal Acta Pharmacologica Sinica, researchers studied the effect of melatonin and cognitive impairment. They wrote: “Alzheimer disease (AD), an age-related neurodegenerative disorder with progressive loss of memory and deterioration of comprehensive cognition, is characterized by extracellular senile plaques of aggregated beta-amyloid (Abeta), and intracellular neurofibrillary tangles that contain hyperphosphorylated tau protein. Recent studies showed that melatonin, an indoleamine secreted by the pineal gland, may play an important role in aging and AD as an antioxidant and neuroprotector. Melatonin decreases during aging and patients with AD have a more profound reduction in this hormone. Data from clinical trials indicate that melatonin supplementation improves sleep, ameliorates sundowning, and slows down the progression of cognitive impairment in Alzheimer patients.” Wang JZ, Wang ZF. Acta Pharmacol Sin. 2006 Jan;27(1):41-9.

Read the abstract here

Obesity and Alzheimer’s Disease
Researchers say that obesity can lead to higher risk of Alzheimer’s disease.

From the press release issued by Thomas Jefferson University Hospital: “A team led by researchers at the Farber Institute for Neurosciences at Thomas Jefferson University in Philadelphia and Edith Cowan University in Joondalup, Western Australia has shown that being extremely overweight or obese increases the likelihood of developing Alzheimer’s. They found a strong correlation between body mass index and high levels of beta-amyloid, the sticky protein substance that builds up in the Alzheimer’s brain and is thought to play a major role in destroying nerve cells and in cognitive and behavioral problems associated with the disease.”

Exercise Delays Onset of Dementia and Alzheimer’s
Larson EB, Wang L, Bowen JD,McCormick WC, Teri L, Crane P, Kukull W. Exercise Is Associated with Reduced Risk for Incident Dementia among Persons 65 Years of Age and Older. Annals of Internal Medicine January 17, 2006 Volume 144 Issue 2 Pages 73-81.

A new study reports a reduced incidence rate of dementia for people who exercised 3 or more times a week compared with those who exercised fewer than 3 times per week.

Say the study authors: “We believe these findings may be useful if they are confirmed because Alzheimer disease is one of the most feared illnesses of aging and is frequently cited as a reason for not wanting to “get old”: People do not want to lose their independence and quality of life as a consequence of aging.”

They conclude: “These results suggest that regular exercise is associated with a delay in onset of dementia and Alzheimer disease, further supporting its value for elderly persons.”

Read the full article here at the Annals of Internal Medicine

Obesity and Alzheimer’s
Midlife Obesity Raises Risk of Alzheimer’s Disease Later
Researchers reporting at the American Academy of Neurology 58th Annual Meeting in San Diego this week say that midlife obesity raises the risk for Alzheimer’s. Read more

Testosterone, Alzheimer’s, Mood and Quality of Life
A study suggets that that testosterone replacement therapy improved overall quality of life in patients with Alzheimers Disease.

Brain Estrogen Deficiency and Alzheimer’s Disease
Writing in the Proceedings of the National Academy of Sciences (USA), researchers studied the effects of estrogen deficiency and Alzheimer’s Disease. They wrote: “Much evidence indicates that women have a higher risk of developing Alzheimer’s disease (AD) than do men. The reason for this gender difference is unclear. We hypothesize that estrogen deficiency in the brains of women with AD may be a key risk factor….Our results indicate that estrogen depletion in the brain may be a significant risk factor for developing AD neuropathology.”

Yue X, Lu M, Lancaster T, Cao P, Honda SI, Staufenbiel M, Harada N, Zhenyu Z, Shen Y, Rena Li R Brain estrogen deficiency accelerates Aβ plaque formation in an Alzheimer’s disease animal model Proc. Natl. Acad. Sci. USA, 10.1073/pnas.0505203102

Melatonin and Alzheimer-like neurodegeneration
Writing in the medical journal Acta Pharmacologica Sinica, researchers studied the effect of melatonin and cognitive impairment. They wrote: “Alzheimer disease (AD), an age-related neurodegenerative disorder with progressive loss of memory and deterioration of comprehensive cognition, is characterized by extracellular senile plaques of aggregated beta-amyloid (Abeta), and intracellular neurofibrillary tangles that contain hyperphosphorylated tau protein. Recent studies showed that melatonin, an indoleamine secreted by the pineal gland, may play an important role in aging and AD as an antioxidant and neuroprotector. Melatonin decreases during aging and patients with AD have a more profound reduction in this hormone. Data from clinical trials indicate that melatonin supplementation improves sleep, ameliorates sundowning, and slows down the progression of cognitive impairment in Alzheimer patients.” Wang JZ, Wang ZF. Acta Pharmacol Sin. 2006 Jan;27(1):41-9.

Read the abstract here

Cortisol Concentrations Predict a Decline in Memory Function
Researchers writing in the medical journal Neurobiology of Aging say their “results partially confirm previous findings that high cortisol is associated with impaired declarative memory function in non-demented older persons. In addition, our data show that high salivary cortisol concentrations predict a decline in memory function over the next 3 years.” Read more

Research and Recent News on Alzheimer’s Disease

How Many Animals You Can Name In One Minute, May Help Determine Risk of Alzheimer’s Disease
Researchers reporting this past Tuesday said that the names of animals (such as Zebra and Giraffe) maybe used to determine who could be in the earliest stages of Alzheimer’s disease.

A study says that common words learned later in life typically disappear from the vocabulary of people in the early stages of Alzheimer’s Disease. An example given is with the names of animals.

Because we typically learn “Dog” and “Cat” in our earliest years, people in the early stages of Alzheimer tend to remember the words, yet other animal names learned later in life, (after age 5) were forgotten, (i.e., words like zebra and giraffe).

In one study, participants were asked to name as many animals as they could in one minute, “healthy” people could list 20-25. Alzheimer sufferer’s could only list 10-15, a significant drop in vocabulary.

You can read more at BBC

What Some Researchers Say You Can Do To Fight Off Memory Loss
Other researchers reporting Wednesday said that the tools to fight off memory loss associated with aging is to:

– Be physically fit
– avoid stress
– be socially active
– learn new things
– and “think young”

They also said that omega-3 (a fish oil) “may reduce the cell inflammation that triggers a decline in memory.”

Read More 

More On Insulin and Aging
A new study, to be published, says that high insulin levels, among both diabetics and non-diabetics, may contribute to Alzheimer’s disease.

To quote the authors of the study “Although this model has obvious relevance for diabetes mellitus, hyperinsulinemia and insulin resistance are widespread conditions that affect many nondiabetic adults with obesity, impaired glucose tolerance, cardiovascular disease, and hypertension. Our results provide a cautionary note for the current epidemic of such conditions, which, in the context of an aging population, may provoke a dramatic increase in the prevalence of AD (Alzheimer’s).”

You can read the entire article at the
Journal of Neurology

Obesity, High blood Pressure, High Cholesterol and Alzheimers Risk
Study published in October 10, 2005 issue of the Archives of Neurology

Midlife obesity puts you at a higher risk for dementia and Alzheimer’s disease than being at normal weight. The researchers noted: “Midlife obesity, high total cholesterol level, and high systolic blood pressure were all significant risk factors for dementia….”

Read the abstract

Examination of the effects of testosterone deficiency on Alzheimer’s Disease
Gouras GK, Hauxi X, Gross R, et al. Testosterone reduces neuronal secretion of Alzheimer’s -amyloid peptides Proc Natl Acad Sci U S A. 2000;3:1202-5.

Interpretation: Examination of the effects of testosterone deficiency on Alzheimer’s Disease

The researchers noted: “Increasing evidence indicates that testosterone, especially bioavailable testosterone, decreases with age in older men and in postmenopausal women….These results raise the possibility that testosterone supplementation in elderly men may be protective in the treatment of Alzheimer’s Disease