What is the brain made of? To the untrained eye, the brain is basically a big grey blob. With the use of advanced imaging technology, though, we are able to see underlying regions and structures that many in the past could not. Our white matter “tracts,” for example, were a mystery until recently. However, with the use of new technology, called diffusion tensor imaging (DTI), we are able to examine and measure the strength of these tracts in living humans. The strength of these tracts is thought to partially represent the strength of connections within the brain. Functional connectivity between different regions rests upon these tracts, so they are thought of as a sort of “skeleton of the brain.” Some people have weaker tracts than others, but what contributes to this weakness? Since we have seen brain damage associated with untreated sleep apnea in the past, could sleep apnea cause or contribute to decreased strength of these white matter tracts?
In a recently conducted study, the white matter tracts of 17 subjects with untreated apnea were compared with 15 subjects without sleep apnea. Subjects with sleep apnea were scanned prior to undergoing any type of treatment, and then again after treatment (continuous positive airway pressure, or CPAP). Their brains were rescanned 3 months and 12 months after treatment initiation. In addition, all subjects underwent mood assessment, neuropsychological testing, and sleepiness ratings before and after treatment.
When comparing the untreated sleep apnea subjects to the normal controls, results showed that the white matter tracts in the sleep apnea subjects had reduced strength, and this reduction in strength was related to cognitive scores, mood and sleepiness. In other words, those with the weakest white matter tracts had worse mood scores, worse cognitive functioning, and greater sleepiness scores. Amazingly, after only 1 year of treatment, the strength of these white matter tracts were increased almost completely to the level of the healthy control group. In addition, scores of cognition, sleepiness, and mood were all increased in relation to increased white matter strength1.
In this study, it was seen that white matter tracts, which are important markers of brain connectivity, were weak in those with untreated sleep apnea, but they were strengthened after 1 year of effective CPAP treatment. Brain connectivity is crucial for proper cognitive functioning and mood regulation, as confirmed here as these scores increased after treatment. Of note, these subjects were only being treated for 1 year when this improvement was seen. In this short amount of time, quality sleep and a reduction of stress on the brain allowed these white matter tracts to strengthen, making a great case for sleep apnea treatment and also quality sleep in general!
Source: Journal: Sleep: White matter integrity in obstructive sleep apnea before and after treatment