Obstructive sleep apnea, in which airways in the nose and mouth collapse due to irritation during sleep, leads to repeated sleep disruption and loud snoring. It also causes memory impairment which, some researchers surmise, results not from simple fatigue but from a specific pattern of neural damage.
Many sleep apnea sufferers have difficulty forming new memories of recent events. Such problems are a hallmark of another condition, Korsakoff’s syndrome, which results from chronic alcoholism, thiamine (Vitamin B1) deficiency or a combination.
Imaging studies show that patients with Korsakoff’s syndrome have damage in the hippocampus, a memory nexus, and the thalamus, a central hub of many brain functions including sensory processing, motor coordination and sleep. Mammillary bodies, structures in between these two areas, are also damaged.
In the June 27 issue of Neuroscience Letters, Ronald Harper and colleagues at the University of California, Los Angeles, performed high-resolution magnetic resonance scans of 43 patients with sleep apnea. Their mammillary bodies showed significantly reduced volume compared with healthy controls. The researchers suspect oxygen deprivation or inflammatory damage as the cause.
Nutritional deficiencies may also play a role. Because thiamine deficiency is a hallmark of Korsakoff’s syndrome, Harper and colleagues are now studying levels of thiamine in sleep apnea patients. Intriguingly, diabetes is also strongly linked with thiamine deficiency, and up to 70 percent of diabetics also have obstructive sleep apnea.
“We don’t have enough evidence yet to issue a blanket prescription of thiamine supplements for sleep apnea, but it’s possible that sleep apnea patients may have a pre-diabetic condition,” Harper says.