Can Sleep Apnea Cause Brain Damage and Can CPAP Reverse It?

Obstructive Sleep Apnea (OSA) causes episodes of hypoxia, fragmented sleep, and excessive sleepiness. These effects can cause brain damage in the form of the destruction of both white and gray brain cells. CPAP therapy has been shown to reverse brain damage caused by OSA.

Obstructive Sleep Apnea (OSA) is a sleep disorder that, when moderate to severe, can result in the following neurological problems:

• Hypoxia (restricted supply of oxygen to the brain and other tissues)
• Fragmented sleep
• Excessive sleepiness.

These three factors are the main contributors to neurological (brain) damage in people with sleep apnea (Knoepke & Aloia, 2009).

Obstructive sleep apnea in its moderate to severe forms can cause brain damage to the extent of deficiency in:

• Attention
• Concentration and executive function (ability to plan, act on plans, etc)
• Verbal and visuospatial memory
• Constructional abilities (the ability to draw figures, lines, and shapes)
• Psychomotor functioning (coordination, speed, strength)

In some cases, OSA can even result in “global intellectual dysfunction and acute delirium” (Knoepke & Aloia, 2009, p. 52). 

Here is a scientific description of the parts of the brain affected by OSA:

“Among the structures injured are the insular, cingulate, and ventral medial prefrontal cortices, as well as cerebellar deep nuclei and cortex, anterior hypothalamus, raphé, ventrolateral medulla, basal ganglia and, in CCHS, the locus coeruleus,” (Harper et al, 2014). 

In plain English, OSA primarily affects the inner layers as well as frontal lobes of the brain in addition to several glands located in the brain. 

Gray matter cells are affected, which translates to a diminished capacity to store and process information. And damage to white matter cells means poorer communication among different regions of the brain. 

Several studies indicate a connection between severe Obstructive Sleep Apnea and a higher risk of dementia. 

The factors taken into account include:

• Higher brain amyloid burden (Jackson et al, 2020)
• Hypoxia (Yaffe et al, 2011)
• Cerebral white matter lesions (CWMLs) (Kum et al, 2017).

In addition, as Kum et al (2017) writes, “CWMLs have been reported to lead to cognitive functional disorders such as dementia and Alzheimer’s disease,” (p. 49). Since the CWMLs are formed in the presence of severe OSA, the link between sleep apnea and Alzheimer’s exists.

Yes. Brain fog is a quite loose umbrella term for a range of cognitive impairment symptoms, many of which can occur as a result of moderate to severe OSA. 

Yes, moderate to severe OSA can cause cognitive impairment, one manifestation of which is mental confusion. 

Mild sleep apnea is unlikely to cause brain damage in adults. However, if you have moderate to severe OSA, then the following are the signs and symptoms of brain damage caused by your OSA:

• Deficits in short-term memory
• Diminished verbal fluency
• Impaired attention and perception
• Many people show evidence of psychosocial dysfunction, such as family problems, depression, and anxiety, among other related issues (Lim et al, 2010)
• Impaired psychomotor functioning (Knoepke & Aloia, 2009)

At this point, you may be wondering, “Is brain damage from sleep apnea reversible?”

Fortunately, CPAP therapy has been shown to almost completely reverse the damage to white cells, dramatically restore gray matter, and increase overall brain volume in patients with severe OSA.

A study published in 2016 by a group of Korean scientists used an MRI scanner to measure overall brain volume and other brain characteristics in two groups of OSA patients – those who received and those who did not receive CPAP treatment.

In a period of 8-44 months, patients in the untreated group showed a significant reduction in brain volume. Conversely, patients with compliant CPAP treatment showed a significant volume increase in the neocortex and other parts of the brain, (Kim et al, 2016).

Another study was done in 2014 measured white matter integrity and cognitive performance in severe OSA patients who underwent compliant CPAP therapy for 12 months.

The results showed no significant changes after three months of treatment. However, after 12 months of CPAP therapy, subjects showed an almost complete reversal of white matter abnormalities in addition to significant correlated improvement in cognitive function, (Castronovo et al, 2014). 

Neurologists tend to treat sleep apnea when its causes are thought to be neurological. In other words, neurologists mainly deal with Central Sleep Apnea (CSA) as opposed to Obstructive Sleep Apnea (OSA). 

References

Castronovo, V., Scifo, P., Castellano, A., Aloia, Iadanza, A., Marelli, S., Cappa, S. F., Strambi, L. F., & Falini, A. (2014). White matter integrity in obstructive sleep apnea before and after treatment. Sleep, 37(9), 1465–1475.

Harper, R. M., Kumar, R., Macey, P. M., Woo, M. A., & Ogren, J. A. (2014). Affective brain areas and sleep-disordered breathing. Progress in Brain Research, 209, 275-293. Retrieved from: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4060533/ 

Jackson, M., Cavuoto, M., Schembri, R., Doré, V., Villemagne, V. L., Barnes, M., O’Donoghue, F., Rowe, C., & Robinson, S. (2020). Severe obstructive sleep apnea is associated with higher brain amyloid burden: A preliminary pet imaging study. Journal of Alzheimer’s Disease, 78(2), 611-617.

Kim, H., Joo, E. Y., Suh, S., Kim, J. H., Kim, S. T., & Hong, S. B. (2016). Effects of long-term treatment on brain volume in patients with obstructive sleep apnea syndrome. Human Brain Mapping, 37(1), 395-409.

Knoepke, C. & Aloia, M. (2009). Proposed mechanisms of cognitive dysfunction in obstructive sleep apnea. Primary Psychiatry, 16(10), 51-56.

Kum, R., Baklaci, D., Ozcan, M., Ciliz, D., Yilmaz, Y., & Unal, A. (2017). Increased risk of cerebral white matter lesions in obstructive sleep apnea syndrome. Sleep & Biological Rhythms, 15(1), 49-55.

Lim, D. C. & Veasey, S. C. (2010). Neural injury in sleep apnea. Current neurology and neuroscience reports, 10(1), 47-52.

Yaffe, K., Laffan A. M., Harrison S. L., et al. (2011). Sleep-disordered breathing, hypoxia, and risk of mild cognitive impairment and dementia in older women. JAMA, 306, 613-9.