One critical memory structure that can be damaged by sleep apnea is the hippocampus, a critical structure for memory. Now a new study breaks down exactly where the hippocampus gets damaged by sleep apnea , showing us more precisely which memory functions get hit hardest. And it shows us that sleep apnea treatment has a protective effect.
Most of the studies of sleep apnea’s impacts on the brain are done using magnetic resonance imagery (MRI). This works well most of the time: it allows us to look at the brain of living individuals and map many structures, including the hippocampus. With MRI, we’ve been able to tell that the hippocampus shrinks because of sleep apnea.
But MRI can’t show the hippocampus in enough detail to look at the separate regions of this tiny brain structure. That’s why researchers in this study opted for autopsy studies, where they could physically measure the thickness of different parts of the hippocampus, allowing them to look at how the individual structures are affected.
Unfortunately, because of the high mortality rate of people with sleep apnea, there are many available cadavers to use for this type of study. In this study, they used 17 female and 15 male cadavers to see how the hippocampus was impacted, and compared the effects with the sleep apnea severity charted for each individual. Researchers could even look at the impact sleep apnea treatment had for some of the individuals.
Self, Spatial, and Basic Memory Affected
Researchers found that as sleep apnea worsened, they saw more serious thinning in layers of the dentate gyrus, a region of cornu ammonis called the CA1, and the entorhinal cortex (EC).
The dentate gyrus helps us form “episodic memories,” which are autobiographical memories that track what happened in time and space. The dentate gyrus also helps us make spatial memories.
Damage to these regions can also lead to diminished semantic memory. Semantic memory is the kind of memory that we might describe as our “basic” memory, since it includes things like letters, names of colors, and simple facts we learn over life. When the hippocampus is damaged, we can find it harder to make and retrieve these kinds of memories.
Sleep Apnea Treatment Helps
What’s remarkable about this study is not just the detailed findings about the impact of sleep apnea on the hippocampus, but the way they could link those findings to worsening sleep apnea. They also found that people who used sleep apnea treatment didn’t have thinning in these regions of the brain–they were protected!
Sleep apnea has the ability to put you at serious risk. It can even, as this study shows, steal your memories. Don’t let it!