Untreated Pain Is Not a Neutral Holding Position

Untreated chronic pain keeps cortisol (the stress hormone) high and switches on microglia in the brain. Those effects build up in the hippocampus and prefrontal cortex, the regions that carry memory, planning and attention. Yet doing nothing is still quietly treated as the zero-risk option.

When a treatment carries risk, the instinct is to compare it against doing nothing. In chronic pain, that comparison is usually made wrong, because “doing nothing” is quietly treated as the zero-risk option.

It is not. Pain that goes on without care has measurable effects on the brain, and those effects build up.

How does untreated chronic pain affect the brain?

Acute pain sets off the hypothalamic–pituitary–adrenal axis, the body’s stress-hormone system. That is normal, and it shuts itself off: the threat passes, and the axis stands down.

Chronic pain does not pass, so the axis does not stand down. The result is constant cortisol exposure. The parts of the brain most sensitive to it are the hippocampus, which locks in memory, and the prefrontal cortex, which handles planning, attention and self-control. Imaging studies in people with chronic pain have often reported less gray matter in these regions. That is compared with controls (similar people used for comparison).

That is not a figure of speech for feeling worn down. It is a physical finding.

Can chronic pain cause brain fog?

Constant pain signals switch on microglia, the brain’s own immune cells. Switched-on microglia release inflammation signals. When that release keeps going, it interferes with synaptic plasticity. That is how the brain builds and rewires its connections.

In the clinic this shows up as the symptoms patients describe long before anyone measures anything. Brain fog. Losing the thread mid-sentence. Reading a paragraph three times. Slower thinking. Patients are often told this is depression, or age, or the medication. Some of it is the pain.

There is also a simpler mechanism running alongside the biology. Pain takes up attention. Mental bandwidth spent on a signal that never lets up is bandwidth you cannot use for memory and decisions.

The comparison that actually matters

The evidence here needs to be stated carefully, because it is often overstated in both directions.

Observational cohorts follow groups of people over time. They have reported associations between chronic pain and later dementia. How strong the link is varies by cohort, by how pain is defined, and by how long people were followed. These are associations. They do not establish that pain causes dementia. Shared risk factors could explain the link, and they are hard to rule out: vascular disease, poor sleep, inactivity, and metabolic problems.

What the data supports is narrower and still useful. Untreated chronic pain travels with cognitive decline (loss of thinking skills) often enough, and through plausible enough mechanisms, that calling it harmless cannot be defended.

The honest framing is that both columns have costs. Long-term high-dose opioid therapy carries real risks. This practice spends most of its clinical effort cutting that burden, not adding to it. See opioid bankruptcy and why tapering is a bridge, not a destination. The mistake is assuming the other column is empty. Choosing not to treat is a choice with consequences. It should be made on purpose, not by default.

How is chronic pain treated to protect the brain?

The practical answer to “pain is damaging the brain” is not a prescription. It is to find and treat the pain generator (the structure making the pain). It is also to address the terrain the pain is running on.

• Identify the source. Facet-mediated, discogenic, neuropathic and centrally maintained pain are different problems with different treatments. Diagnostic blocks pinpoint the first; see facet joint pain and the medial branch nerves.
• Treat it directly. Interventional options aim at the generator instead of masking the signal. These include radiofrequency ablation, epidural and sympathetic blocks, and neuromodulation (devices that change nerve signals).
• Fix the metabolic substrate. Insulin resistance and visceral adiposity (fat packed around the organs) are pro-inflammatory states. They lower pain thresholds. This is not a side issue to pain treatment; it often is the treatment. See hyperinsulinemia and chronic pain and treating metabolic disease at the dietary root cause.
• Protect sleep. Poor sleep amplifies pain and, on its own, harms thinking. The two feed each other.

Where pain medicine has a role while those steps take effect is a limited clinical call. It is made per patient, and it is truly debated in the field. It is a bridge, not a destination.

Frequently asked questions

Does chronic pain cause dementia?

The evidence shows an association, not proven causation. Observational cohorts report more later decline in thinking among people with chronic pain. But shared risk factors are hard to rule out. The reasonable conclusion is that untreated pain is a risk worth addressing, not that it guarantees dementia. See reducing pain risk with early brain stimulation for one line of work on early treatment.

Is brain fog from the pain or the medication?

It can be either, and often both. Opioids, gabapentinoids, antidepressants and sleep medications all affect thinking, and so does the pain itself. Sorting it out means reviewing the whole regimen instead of assuming. Do not start, stop, or change any medication without consulting your physician.

If opioids are risky, what is the alternative?

Treating the pain generator directly. That is what interventional pain medicine does. See radiofrequency ablation , combined with metabolic work that lowers the baseline level of inflammation. See treating metabolic disease at the dietary root cause.

Can the brain changes reverse?

Some imaging studies have reported partial return to normal in gray matter measures after pain is successfully treated. That is encouraging, but it is not a guarantee. Individual results vary.

Where can I be evaluated?

Padda Institute, 4477 Woodson Rd, Suite 100, St. Louis, MO 63134, serving the St. Louis region across Missouri and Illinois. Call (314) 481-5000 or text (314) 886-5902.

Key takeaways

• Untreated chronic pain keeps cortisol high and keeps microglia switched on. Both are bad for memory and executive function (planning and self-control).
• Reported links between chronic pain and later cognitive decline are associations, not proven causation. But the mechanisms are plausible.
• The real comparison is between two columns of risk, not between a risky treatment and a safe nothing.
• Treatment here means finding and treating the pain generator, plus fixing the metabolic terrain.
• Brain fog in chronic pain deserves a regimen review, not an assumption.

This article is educational and is not a substitute for evaluation, diagnosis, or treatment by a physician. Individual results vary. Do not start, stop, or change any medication without consulting your physician.

Medically reviewed by Gurpreet Singh Padda, MD, MBA, MHP — Board Certified in Anesthesiology, Pain Medicine, Interventional Pain Management, Addiction Medicine, and Obesity Medicine. Last reviewed August 2026.

Dr. Gurpreet Singh Padda, MD, MBA, MHP