There’s been a lot of press recently about the side affects that poor sleep quality has on our cognitive functioning not to mention what it means for those who suffer from neurological problems like Alzheimers.
This month, our expert article is contributed by noted neurologist and author of Deadly Sleep, Dr. Mack Jones, who explains the reason why he thinks everyone who has Alzheimers or is at risk for this problem should get tested for a sleep breathing problem like OSA.
Is it possible that Obstructive Sleep Apnea (OSA) causes Alzheimer’s Disease (AD)? I believe so. As a retired clinical neurologist and former patient with Obstructive Sleep Apnea, I have a special interest in sleep disorders medicine. I am thoroughly convinced of the connection between OSA and AD and will remain so until credible studies prove otherwise. Numerous short term studies have been done on cognition (mental processes) and sleep or the lack thereof, but there are few or no long term studies to determine OSA’s relationship to Alzheimer’s Disease (AD) and/or the other dementias.
Many polysomnograms (PSGs) or in lab sleep tests have been done on patients with AD revealing an incidence of OSA of up to seventy to ninety percent. The assumption has been that AD causes OSA, or they just happened to coincide, but I contend that OSA is the cause of AD.
There are no studies that either prove or disprove my hypothesis that long standing undiagnosed OSA is a cause of AD, but evidence is accumulating. For example, OSA is a recognized risk for Type 2 Diabetes. In the April 2008 issue of The Archives of Neurology, type 2 Diabetics had an increased risk or developing Mild Cognitive Impairment (MCI)(1) which is the earliest stage of dementia. Fifty to sixty percent of patients with MCI progress to AD at rate of twelve percent per year.
Additionally, OSA is a known risk for the development of high blood pressure. Like patients with Type 2 diabetes, those with high blood pressure were also found to have an increased risk of developing MCI.(2) Since the majority of patients with MCI eventually progress to Alzheimer’s Disease at a rate of approximately twelve percent per year, then it’s not a stretch to conclude that OSA is a cause of Alzheimer’s Disease.
In 2006 a study in the Proceedings of the National Academy of Sciences showed low brain oxygen (hypoxia) raises Alzheimer’s risk in the mouse brain with a genetic susceptibility.(3) A group of mice with an Alzheimer’s gene were given a maze test in which they all performed normally. They were separated into two groups, one exposed to 16 hours of a reduced oxygen environment (hypoxia) daily for several weeks; the other group in a normal environment.
The maze test was repeated and revealed the hypoxic mice performed poorly, whereas the control groups performance remained normal as before. All the mice were sacrificed and their brains examined under the microscope. Plaques and neurofibrillary tangles typical of Alzheimer’s Disease were present in the hypoxic mouse brain specimens, whereas the controls were normal. According to investigators, the study suggests that preventing brain hypoxia (as occurs in OSA) may reduce the risk of developing Alzheimer’s Disease.
Reported in the June 27th issue of Neuroscience Letters, sleep apnea patients have shrunken brain structures called “mammillary bodies” involved in memory according to Rajesh Kumar, PhD and colleagues from the University of California at Los Angles (UCLA). High resolution MRI brain scans revealed mammillary bodies to be twenty percent smaller in patients with sleep apnea than in normals. “These findings are important because patients suffering from memory loss from other symptoms, such as alcoholism or Alzheimer’s Disease, also show shrunken mammillary bodies,” Dr. Kumar said in a press release.
A recent study form San Diego showed that Sleep Disordered Breathing, including OSA, is and important risk factor for cognitive impairment in older women. (4)
Neuroimaging studies have been performed on patients with OSA including CT, MRI. PET and SPECT scans, revealing a variety of defects, but none has displayed anything quiet as dramatic as in a study published in SLEEP July7, 2008, by Dr. Paul M. Macey et al. (5) The report reveals results of a new MRI technology called DTI (Diffusion Tensor Imaging). It is an extremely sensitive method of determining damaged nerve fibers (axons). This new imaging technique reveals multiple areas of brain damage in OSA patients not known to exist until now. DTI revealed various sized color-coded yellow-orange patches of brain damage scattered throughout the brains of a group of forty-one men and women subjects with OSA. Their ages ranged from thirty-eight to fifty two years old and they had not yet been treated. The areas of nerve fiber injury were wide-spread, located in critical regions of brain including prefrontal, temporal and parietal lobes. The cerebellum and brainstem were equally involved. This is the first report of DTI imaging of a group with OSA to my knowledge. The findings have far-reaching implications.
One can anticipate finding even more areas of damage in an older population as studies are done. What problems result from each one of these areas of brain damage? It is possible that they are responsible for difficulties with cognition, mood, behavior, memory, heart regulation, high blood pressure, breathing control, fear, anxiety and other emotional disorders including depression? Those findings are yet to be reported. Could this brain damage eventually accumulate enough to cause Alzheimer’s Disease and/or the other dementias?
The structural changes likely represent accumulated damage over sustained periods of time. Are they permanent or do they improve or disappear with treatment? No one knows yet, but my guess is they may improve to some degree or even resolve with treatment, but we will have to wait and see.
The implications of these findings are profound. Early treatment of OSA could potentially prevent the development of Alzheimer’s Disease. Now is the time to wake up the public and our snoozing medical community and put an end to this disease.
1. José A. Luchsinger, M.D. et al, Relation of Diabetes to Mild Cognitive Impairment, Arch Neurol. 2007; 64 (4):570-575.
2. Christine Reitz, M.D. PhD, et.al. Hypertension and the Risk of Mild Cognitive Impairment:, Arch Neurol. 2007; 64(12):1734-1740.
3. Xiulian Sun, et al, Hypoxia Facilitates Alzheimer’s Disease Pathogenesis By Up Regulating BACE1 Gene Expression. PNAS (Proceedings of the National Academy of
Sciences) 2006 | vol.103 | no. 49 |18727-18732
4. Adam P. Spira, et al, Disordered Breathing and Cognition in Older Women: Journal of the American Geriatrics Society. Volume 56, issue 1, January 2008, 45-50.
5. Paul M. Macey, et al, “Brain Structural Changes in Obstructive Sleep Apnea," SLEEP vol.32, Number July 7, 2008, 913-1056.
After surviving his four year ordeal in search for a cure of his own sleep apnea, Dr. Mack Jones, a clinical neurologist, felt a need to pass on to others what he learned first-hand as a patient, so that you might avoid the pitfalls he encountered and possibly save your own life or the lives of your loved ones. Dr. Jones in his book, Deadly Sleep, expected publication date, June of 2009, discusses how this common sleep disorder is a likely cause of Alzheimer’s and possibly a host of other life threatening neurological diseases that may have been plaguing us for hundreds if not thousands of years. He can be contacted via e-mail by clicking here.