One of the most common complaints by my patients with obstructive sleep apnea (OSA) is memory loss. Judith is a 55 year old woman who used to have a sharp memory, but now is having trouble with names and losing her keys all the time. Things got much worse when she gained more weight, which worsened her snoring. She was eventually placed on CPAP for her moderate obstructive sleep apnea, and is now happy to report that while her memory is not back to normal, it is much improved.
At a recent Airway Dentistry conference I went to last month, the most memorable topic was given by Dr. Ronald Harper, Distinguished Professor of Neurobiology at the David Geffen School of Medicine at UCLA. I’ve been following his work over many years, but his presentation only confirmed my suspicion that there can be significant brain damage with untreated obstructive sleep apnea. Based on various high-tech MRI technology, specific known areas of the brain can be damaged with repeated episodes of apneas and low oxygen levels. Note that the word “damage” can mean low functioning, or dead brain cells. Here are 5 particular areas of brain damage from untreated obstructive sleep apnea with their specific symptoms:
1. The right insular cortex. This is the area of the brain that regulates sympathetic control of the autonomic nervous system. If the insular cortex is damaged, baroreflex control is affected. The insula also controls nerve endings that relate to pain. Both OSA and sleep apnea patients are found to have insular cortex injury.
2. The vetrolateral medulla (VLM). This area of the brain controls breathing and blood pressure regulation. Injury to this area blunts and delays heart rate responses to sudden pressure changes. One sided VLM injury leads to an asymmetric response to blood pressure challenge, which can potentially cause heart rhythm problems.
3. The cerebellum is the area of the brain that helps adjust blood pressure control and motor coordination, including breathing. Damage to this area prevents the ability to coordinate vascular and motor activity.
4. The hippocampus is found to be significantly smaller in people with obstructive sleep apnea. This area of the brain processes short and long-term memory and spatial navigation. One study found that hippocampal damage can be partially reversed after a period of CPAP. The hippocampus is also one of the first areas to be damaged in Alzheimer’s disease.
5. Mammary bodies are important for memory recall, as well as for memory for certain smells. These structures are much smaller in patients with OSA, and almost nonexistent in patients with heart failure. The hippocampus and mammary bodies are also found to be damaged in chronic alcoholism.
If OSA can damage critical areas of the brain that regulates breathing, balance, memory, and the autonomic nervous system, the implications are enormous. For example, heart failure is thought to lead to central sleep apnea. Is it possible that untreated obstructive sleep apnea can damage breathing and reflex centers in the brain that can lead to heart failure? What proportion of Alzheimer’s disease is actually undiagnosed OSA? The possibilities are endless. As they say at the end of every scientific journal article, more studies are needed.
If you have both OSA and memory problems, did your memory improve at all after being treated? Please tell your story below.
(Take a look at the references below to take a look at the various photos and figures. The figure above is from the Macey 2002 paper)
Canessa, N., Castronovo, V., Cappa, S. F., Aloia, M. S., Marelli, S., Falini, A., et al. (2011). Obstructive Sleep Apnea: Brain Structural Changes and Neurocognitive Function before and after Treatment. American Journal of Respiratory and Critical Care Medicine, 183(10), 1419–1426
Henderson, L. A., Woo, M. A., Macey, P. M., Macey, K. E., Frysinger, R. C., Alger, J. R., et al. (2003). Neural responses during Valsalva maneuvers in obstructive sleep apnea syndrome. Journal of Applied Physiology (Bethesda, Md. : 1985), 94(3), 1063–1074.
Kumar, R., Chavez, A. S., Macey, P. M., Woo, M. A., Yan-Go, F. L., & Harper, R. M. (2012). Altered global and regional brain mean diffusivity in patients with obstructive sleep apnea. Journal of Neuroscience Research, 90(10), 2043–2052.
Macey, P. M., Henderson, L. A., Macey, K. E., Alger, J. R., Frysinger, R. C., Woo, M. A., et al. (2002). Brain Morphology Associated with Obstructive Sleep Apnea. American Journal of Respiratory and Critical Care Medicine, 166(10), 1382–1387.
Macey, P. M., Kumar, R., Woo, M. A., Valladares, E. M., Yan-Go, F. L., & Harper, R. M. (2008). Brain structural changes in obstructive sleep apnea. Sleep, 31(7), 967–977.
Lal, C., Strange, C., & Bachman, D. (2012). Neurocognitive impairment in obstructive sleep apnea. CHEST Journal, 141(6), 1601–1610.