Sleep-disordered breathing is a risk factor for dementia in women

Posted on August 29, 2011 by Dr. Jonathan

Adding to the damage list associated with sleep-disordered breathing, a study just published in JAMA (The Journal of the American Medical Association) offers evidence that sleep apneas and hypopneas can contribute to serious cognitive impairment. This is not surprising considering the importance of oxygen for brain health. The authors state:

“Sleep-disordered breathing (characterized by recurrent arousals from sleep and intermittent hypoxemia) is common among older adults. Cross-sectional studies have linked sleep-disordered breathing to poor cognition…”

So they designed their study to…

“…determine the prospective relationship between sleep-disordered breathing and cognitive impairment and to investigate potential mechanisms of this association.”

Defining sleep-disordered breathing as an apnea-hypopnea index of 15 or more events per hour of sleep, they examined polysomnography (‘sleep study’) data for 298 women without dementia collected between January 2002 and April 2004. They then used data collected between November 2006 and September 2008 to correlate hypoxia, sleep fragmentation, and sleep duration with cognitive status (normal, dementia, or mild cognitive impairment). What did the data reveal?

“Compared with the 193 women without sleep-disordered breathing, the 105 women (35.2%) with sleep-disordered breathing were more likely to develop mild cognitive impairment or dementia (31.1% vs 44.8%). Elevated oxygen desaturation index (≥15 events/hour) and high percentage of sleep time (>7%) in apnea or hypopnea (both measures of disordered breathing) were associated with risk of developing mild cognitive impairment or dementia (AOR, 1.71 and AOR, 2.04, respectively).”

In other words, the higher strata of sleep-disordered breathing doubled the risk for dementia. Interestingly…

“Measures of sleep fragmentation (arousal index and wake after sleep onset) or sleep duration (total sleep time) were not associated with risk of cognitive impairment.”

Clinicians need to bear in mind the serious metabolic, cardiovascular and cognitive penalties of sleep-disordered breathing and question patients about tell-tale signs such has heavy snoring and daytime somnolence. The authors conclude:

“Among older women, those with sleep-disordered breathing compared with those without sleep-disordered breathing had an increased risk of developing cognitive impairment.”

This study cohort was all female subjects, but I can think of no reason why the same consideration does not apply to male patients.

Metabolic syndrome promotes cognitive decline

Posted on February 27, 2011 by Dr. Jonathan

More evidence that metabolic syndrome, and its root causal factor insulin resistance, are damaging to the brain and promote cognitive decline appears in a study just published in the journal Neurology. The authors set out to…

“…examine associations between metabolic syndrome (MetS) and its individual components with risk of cognitive decline on specific cognitive functions.”

The assessed 4,323 women and 2,764 men aged 65 and over for cognitive decline and metabolic syndrome (possessing at least 3 of 5 cardio-metabolic abnormalities: hypertension, high waist circumference, hypertriglyceridemia, low high-density lipoprotein [HDL] cholesterol, hyperglycemia). The risk evaluation was adjusted for a number of variables including the APOE4 genotype. What did their data show?

“MetS at baseline was associated with an increased risk of cognitive decline on MMSE [Mini-Mental State Examination for global cognitive function]…. Among MetS components, hypertriglyceridemia and low HDL cholesterol were significantly associated with higher decline on MMSE; diabetes, but not elevated fasting glycemia, was significantly associated with higher decline on BVRT [Benton Visual Retention Test for visual working memory]and IST [Isaacs Set Test for verbal fluency].”

The practical message for clinicians and the public is that blood sugar and insulin regulation are critical factors for brain health. Management begins with diet and lifestyle factors including exercise and encompasses specific needs for supplementation as determined by reliable laboratory investigations that disclose individual genetic and epigenetic factors. The authors conclude:

“MetS as a whole and several of its components had a negative impact on global cognitive decline and specific cognitive functions in older persons.“

Walking helps prevent brain atrophy and dementia

Posted on October 21, 2010 by Dr. Jonathan

Not only does walking for exercise have favorable metabolic and hormonal effects; a study just published in the journal Neurology provides evidence that it is a beneficial stimulus to the brain. The authors state:

“Here we tested whether PA [physical activity] would be associated with greater gray matter volume after a 9-year follow-up, a threshold could be identified for the amount of walking necessary to spare gray matter volume, and greater gray matter volume associated with PA would be associated with a reduced risk for cognitive impairment 13 years after the PA evaluation.”

They examined 299 adults for the the association between gray matter volume, physical activity (quantified as the number of blocks walked per week), and cognitive impairment. After 9 years high-resolution brain scans were acquired. Examination for cognitive impairment was done 13 years after the start of the study. What did the data show?

“Greater PA predicted greater volumes of frontal, occipital, entorhinal, and hippocampal regions 9 years later. Walking 72 blocks [per week] was necessary to detect increased gray matter volume but walking more than 72 blocks did not spare additional volume. Greater gray matter volume with PA reduced the risk for cognitive impairment 2-fold.“

The authors summarized the evidence by concluding:

“Greater amounts of walking are associated with greater gray matter volume, which is in turn associated with a reduced risk of cognitive impairment.“

Vitamin D for cognitive decline and Parkinson’s Disease

Posted on July 25, 2010 by Dr. Jonathan

Two studies have just been published linking Vitamin D status to brain health. The authors of one paper appearing in Archives of Internal Medicine observe:

“To our knowledge, no prospective study has examined the association between vitamin D and cognitive decline or dementia.”

They examined the correlation between low levels of serum 25-hydroxyvitamin D (25[OH]D) and the risk of serious loss of cognitive function in 858 adults over 8 years. What did the data show?

“…substantial cognitive decline on the MMSE [Mini-Mental State Examination] in participants who were severely serum 25(OH)D deficient (levels <25 nmol/L) in comparison with those with sufficient levels of 25(OH)D (≥75 nmol/L)…the scores of participants who were severely 25(OH)D deficient declined by an additional 0.3 MMSE points per year more than those with sufficient levels of 25(OH)D.”

Thus their conclusion:

“Low levels of vitamin D were associated with substantial cognitive decline in the elderly population studied over a 6-year period, which raises important new possibilities for treatment and prevention.”

The same week a study was published in Archives of Neurology that examines the relation between Vitamin D and Parkinson Disease. The authors set out to:

“…investigate whether serum vitamin D level predicts the risk of Parkinson disease.”

They crunched the numbers for 3,173 men and women who were followed up over 29 years (the baseline serum 25-hydroxyvitamin D level was determined from frozen samples) for the relationship between serum vitamin D concentration and Parkinson disease. The data showed that:

“Individuals with higher serum vitamin D concentrations showed a reduced risk of Parkinson disease. The relative risk between the highest and lowest quartiles was 0.33 [about a third less] after adjustment for sex, age, marital status, education, alcohol consumption, leisure-time physical activity, smoking, body mass index, and month of blood draw.”

Thus their conclusion:

“The results are consistent with the suggestion that high vitamin D status provides protection against Parkinson disease.”

The results of these studies are not surprising considering that Vitamin D is necessary for regulating the immune inflammatory response and both dementia and Parkinson’s involve chronic brain inflammation. By the way, as stated in Science Insider:

“Most Alzheimer’s disease (AD) researchers agree that the disease starts ravaging the brain years, if not decades, before the first symptoms of forgetfulness appear.”

New diagnostic criteria were just proposed at the International Conference on Alzheimer’s Disease in Honolulu.

Mechanisms of cognitive decline, one of the greatest threats of aging

Posted on April 11, 2010 by Dr. Jonathan

Nature Vol 464 There is a lot being written about the ability of the brain to compensate for age-related changes with enhanced connectivity and efficiency that makes for better judgment and emotional maturity. The sad truth is that the brains of at least 50% of us will have sustained too much damage for this to come to fruition. The authors of an extensive review just published in the journal Nature begin with a statement important for anyone reading this:

“Cognitive frailty is emerging as one of the greatest health threats of the twenty-first century. As the life expectancy of the population has increased, so too has the prevalence of cognitive decline and dementia, largely in the form of Alzheimer’s disease, which now affects almost 50% of adults over the age of 85 in the United States1. This startling figure can only grow as the average age of the population rises, so understanding the basis of cognitive decline during ageing is critical.”

They proceed to describe some of the major categories that define the process of molecular aging as it pertains to cognitive decline, noting that:

“…altered regulation of fundamental mechanisms of ageing may contribute to the pathogenesis of neurodegenerative disorders.”

It is this kind of attention to fundamental mechanisms with a systems biology perspective that is inherent to the functional medicine approach. The authors identify these major factors:

Mitochondrial dysfunction (the ability of brain cells to produce energy to function and repair)
Oxidative damage
Epigenetic changes (changes in genes due to environmental stimuli)
Autophagy and protein turnover (housecleaning)
Insulin signalling

Additionally, they describe the role of the brain as the master regulator of aging throughout the body.

Their list is not complete—there are additional factors that we attend to including neurotransmitter metabolism and receptor sensitivity, fatty acid cell membrane integrity, the role of steroid hormones in the brain, autoimmune inflammation, excess cortisol (stress hormone) production, etc. If you want to be realistic about a strategy for preventing cognitive decline and Alzheimer’s disease, these are the kinds of things that you have to ask you doctor about and make sure they are being attended to.