The Fog After the Table: Part 2
Biological Blockades
POCD (Post-Operative Cognitive Dysfunction)
POCD occurs as an after effect of anesthesiology. It’s distinctly separate from the first 1-3 days after waking from anesthesia, as in those first three days a person who is in recovery is usually confused. POCD is where your thinking skills such as memory, attention, processing speed, word-finding and executive function, all take a major loss and continue to do so for an extended period of time. It’s almost as if you no longer have the ability to think clearly. It’s brain fog but on a much deeper level. It’s a common occurrence from hospitals across many ages, but it’s found more in younger and middle aged people. From the ISPOCD2 study (Johnson et al., Anesthesiology, 2002) this effect occurs in patients between the ages of 40 and 60 to about 19% of patients after one week, and 6.2% at three months. My fog window, at 4 months, is at the longer end of the spectrum. Lucky me.
From what I’ve learned, POCD happens because of neuro-inflammation triggered by surgical trauma, not the anesthetic drugs themselves. POCD also correlates with other contributors such as poor sleep, pain medication, dehydration and mood changes.
Picture it, your living room, 2026. You’re watching television. A paid advertisement comes on. Some of you might be old enough to remember those, where they last about an hour, some lady can’t figure out how to stack dishes without throwing one across the room for no reason and looking completely perplexed about it. Then suddenly here’s a product to keep her from doing it for just 4 payments of $19.95. You know there’s some way to make the TV stop showing you this program, but you can’t remember how. It takes you about 5 minutes to remember there’s a device that exists, but you can’t remember what it’s called. You then look over on the other side of the couch. You know it’s there, but all you can see is this dense fog of grey, and if you can just get past it, just move yourself to reach through the fog, you can get the thing…the somewhat long, black, rectangle device, to make the TV stop showing the ad. But you can’t do it. So you get frustrated and just sit there. Every day. For several days. That’s what this felt like for me. For someone who thinks constantly about everything, everywhere, all at once, it was my personal nightmare.
Vitamin D-ficient
Let’s start with a statistic. 35% of adults in the United States have vitamin D deficiency. This statistic was given by the Cleveland Clinic. There’s a lot of us suffering from this, and I believe a lot don’t know. I surely didn’t because I did not wake up one day at 13 ng/ML, I must have been declining for a while and had no idea.
All vitamins are important, but vitamin D specifically relates to cognitive function. There are receptors for vitamin D in the brain, including in the hippocampus and dentate gyrus, which are directly related to memory and learning. It helps to regulate mood, serotonin and dopamine. Plus it has anti-inflammatory effects. Missing it, combined with POCD effects can cause brain-fog type symptoms of trouble concentrating, mental sluggishness, fatigue, and low mood.
I didn’t realize I had low vitamin D until I requested that the bloodwork be tested while I was in the hospital. Way too much money later, my doctor called me personally to tell me the news. 50,000 units weekly of vitamin D later, it’s finally kicking in. Now most of what I found stated that the effects of low vitamin D are correlational…however, a combination of the lack of the vitamin in addition to the POCD, sleep apnea and everything else that went on, did not help.
Sleep Lacknea
Have you ever been on a bus or around a friend and they snore so loudly that they can be heard 3 blocks over? Or you hear someone snore, and then they stop breathing, cough/snort, and wake themselves up? That’s sleep apnea. When you have sleep apnea, the muscles in the back of the throat relax and the tongue collapses onto the airway. Several times an hour. Each time this happens, you stop breathing, so you wake yourself up, stripping you from the ability to enter into REM sleep. REM sleep is the sleep stage where your brain runs it’s “cleaning cycle”. As a result, you can sleep 7 to 8 and sometimes more hours and still wake up exhausted and foggy.
Due to the lowered oxygen, the small blood vessels which drive the blood flow to the brain and therefore gives it oxygen, are damaged. The brain wakes up clogged, and the classic symptoms of morning fog, headaches, slower processing and the inability to find the correct words remain and affect the individual throughout the day.
Thankfully this is reversible. A 2025 prospective study of 60 patients with moderate-to-severe OSA found that after three months of CPAP there were “significant improvements in executive function (p < 0.001), attention (p < 0.001), and delayed recall (p < 0.001),” concluding there is “partial reversibility of neurocognitive impairment.” Other research suggests early gains in focus and reduced brain fog within the first 1–4 weeks of consistent CPAP use, with larger memory gains over 3–6 months; one review found 12 months of CPAP can reverse white-matter abnormalities.
Citations For More Reading
POCD
Lindquist, S. B. (2018, July 19). Anesthesia, surgery linked to subtle decline in memory and thinking in older adults, Mayo study finds - Mayo Clinic News Network. Anesthesia, surgery linked to subtle decline in memory and thinking in older adults, Mayo study finds. https://newsnetwork.mayoclinic.org/discussion/anesthesia-surgery-linked-to-subtle-decline-in-memory-and-thinking-in-older-adults-mayo-study-finds/
Ahmadzadeh Amiri, A., Karvandian, K., & Ramezani, N. (2020, September 24). Short-term memory impairment in patients undergoing general anesthesia and its contributing factors - PMC. Short-term memory impairment in patients undergoing general anesthesia and its contributing factors. https://pmc.ncbi.nlm.nih.gov/articles/PMC7796728/
Vitamin D
Medically Reviewed (Ed.). (2022, August 2). Vitamin D deficiency: Causes, symptoms & treatment. Vitamin D Deficiency. https://my.clevelandclinic.org/health/diseases/15050-vitamin-d-vitamin-d-deficiency
Moriarty, C. (2018, March 15). Vitamin D myths ’d’-bunked | news | yale medicine. Vitamin D Myths ’D’-bunked. https://www.yalemedicine.org/news/vitamin-d-myths-debunked
Sleep Apnea
Mayo Clinic Staff. (n.d.). 8 facts about obstructive sleep apnea - Mayo Clinic Press. 8 Facts about obstructive sleep apnea . https://mcpress.mayoclinic.org/sleep-apnea/8-facts-about-obstructive-sleep-apnea/
Staff Writer. (13AD). How treating sleep apnea may protect your brain and lower dementia risk - inventum. Clinical Care. https://news.med.miami.edu/sleep-apnea-brain-health-dementia-risk/
Šarić Jurić J, Grebenar Čerkez M, Zubčić Ž, et al. Neurocognitive
Recovery Following Continuous Positive Airway Pressure Therapy in
Patients with Moderate to Severe Obstructive Sleep Apnea. J Clin Med. 2025;14(23):8319. Published 2025 Nov 23. doi:10.3390/jcm14238319 https://pubmed.ncbi.nlm.nih.gov/41375622/
