Chronic fatigue syndrome: Changes in brain chemistry found

What Is ME/CFS?

ME/CFS is a serious, often long-lasting multisystem disease. Its defining feature is not simply fatigue. The condition reduces a person’s ability to function at work, school, home, or socially, and the loss of function can persist for months or years. Rest does not reliably restore normal energy.

The hallmark symptom is post-exertional malaise, commonly shortened to PEM. Physical, mental, emotional, or even sensory effort can worsen symptoms, often 12 to 48 hours later. A grocery trip, an intense conversation, a shower, or an hour of focused computer work may trigger a crash lasting days or weeks.

Common ME/CFS Symptoms

• Severe reduction in the ability to perform usual activities
• Post-exertional malaise after physical or cognitive effort
• Unrefreshing or disturbed sleep
• Problems with memory, attention, and processing speed, often called brain fog
• Dizziness, rapid heartbeat, or worsening symptoms while upright
• Muscle or joint pain, headaches, and sensitivity to light or sound

There is currently no single laboratory test that confirms ME/CFS. Clinicians diagnose it by evaluating the symptom pattern, measuring the decline from previous function, and ruling out other explanations such as anemia, thyroid disease, sleep disorders, autoimmune illness, medication effects, and neurological conditions.

The Study Behind the “Changes in Brain Chemistry” Headline

The widely reported finding came from research led by Dr. James Baraniuk at Georgetown University Medical Center and published in Scientific Reports in 2017. The team compared people with chronic fatigue syndrome, people with Gulf War illness, and sedentary healthy controls.

Participants underwent lumbar punctures so researchers could study cerebrospinal fluid, the clear liquid surrounding the brain and spinal cord. Some participants completed a 25-minute session on a stationary bicycle, and samples were collected before or after the exercise challenge. Researchers then measured tiny regulatory molecules called microRNAs.

What Are MicroRNAs?

MicroRNAs are short strands of genetic material that help regulate whether cells increase or decrease the production of certain proteins. Think of them less as construction workers and more as highly opinionated foremen holding clipboards. They do not build proteins themselves, but they can influence which cellular instructions are carried out.

Before exercise, the cerebrospinal-fluid microRNA levels did not clearly separate the illness groups from the controls. After exercise, distinct patterns appeared. The chronic fatigue syndrome group showed reductions in a set of microRNAs, while two subtypes of Gulf War illness produced different patterns.

That distinction mattered because the disorders can share symptoms, yet the findings suggested that their post-exertional responses may arise through different biological pathways.

What the Study Did Not Prove

The study did not show that a single microRNA causes ME/CFS. It did not establish a commercial diagnostic test, reveal a universal biomarker, or prove that every patient has the same molecular pattern. Cerebrospinal-fluid sampling is invasive, the groups were relatively small, and findings from one controlled experiment must be replicated in broader populations.

It is also important to understand the phrase brain chemistry. The study was not primarily reporting a simple shortage or excess of a familiar neurotransmitter such as serotonin or dopamine. It identified changes in regulatory molecules within fluid associated with the central nervous system after exertion. That is more complexand scientifically more interestingthan a one-chemical explanation.

Why Exercise Triggered a Detectable Signal

For many diseases, researchers learn more by observing the body under stress than by measuring it at rest. A heart may look fine while a person is sitting quietly but behave differently during a stress test. ME/CFS research increasingly uses a similar idea: exertion may expose abnormalities that are quiet or difficult to detect at baseline.

This approach fits the lived reality of PEM. A person can appear relatively stable during an appointment and become significantly worse the following day. The delay has sometimes confused clinicians, employers, and relatives. Biology, regrettably, does not schedule its crashes for the convenience of office hours.

The Georgetown findings raised the possibility that exertion initiates or unmasks changes in gene regulation within the central nervous system. Later research has explored related questions involving inflammation, cellular energy production, blood flow, autonomic control, and the brain’s evaluation of effort.

Newer Research Adds Pieces to the Brain-Chemistry Puzzle

Elevated Lactate and Energetic Stress

Magnetic resonance spectroscopy, or MRS, estimates concentrations of certain chemicals in living tissue. In a 2025 study using ultra-high-field 7-Tesla MRS, the ME/CFS group had elevated lactate in two areas of the anterior cingulate cortex, regions involved in cognition, pain, emotion, and effort processing.

Lactate is a normal product and fuel in energy metabolism, not simply “waste.” Elevated levels in a particular context may still indicate altered energy use or energetic stress. Earlier MRS studies also reported increased ventricular lactate and lower glutathione, a major antioxidant, supporting continued investigation of oxidative stress and impaired energy metabolism.

These are research findings, not clinical tests. Scanner strength, brain region, patient selection, medication use, and analysis methods can influence results, and one metabolite cannot summarize a multisystem disease.

Brain Networks That Calculate Effort

A detailed National Institutes of Health study published in 2024 evaluated 17 people with post-infectious ME/CFS and 21 healthy controls. Participants underwent extensive immune, metabolic, autonomic, cognitive, and brain-imaging assessments.

Researchers found lower activity in the temporal-parietal junction, a brain region involved in integrating information and helping regulate effort-related decisions. Participants also had difficulty sustaining effort, while the motor cortex remained unusually active during fatiguing tasks. The study did not find signs of ordinary muscle fatigue that could fully explain the experience.

This supports a model in which fatigue may involve disrupted communication between brain regions that estimate effort and those that direct movement. It does not mean symptoms are imaginary or chosen. Quite the opposite: the machinery that evaluates and produces effort may be functioning abnormally.

Possible Neuroinflammation

Small positron emission tomography studies have reported signals consistent with activation of microglia or astrocytesthe brain’s support and immune-related cellsin several regions. Reviews of neuroimaging research have also found recurring evidence compatible with altered brain function and neuroinflammation, although results vary considerably among studies.

Why the inconsistency? ME/CFS may contain multiple biological subtypes. Studies have used different diagnostic definitions, imaging technologies, illness severities, and comparison groups. Some enrolled people soon after an infection; others studied patients ill for decades. Combining those groups can be like averaging the weather in Miami and Minneapolis and declaring that America feels “pleasantly moderate.”

How Brain Changes May Connect With Immune Dysfunction

Many people report that ME/CFS began after a viral-like or bacterial illness. Researchers have therefore investigated whether an infection can leave the immune system persistently activated, poorly regulated, or unable to return to its previous equilibrium.

The 2024 NIH investigation found differences in immune-cell populations and markers in blood and cerebrospinal fluid. Stanford researchers have separately reported relationships between disease severity and concentrations of several cytokines, the signaling proteins immune cells use to communicate. These findings do not identify one universal immune defect, but they support continued study of immune-to-brain signaling.

A plausible research model looks like this: an infection or another trigger alters immune activity; immune signals affect the brain, blood vessels, autonomic nervous system, or cellular metabolism; exertion places additional demand on already strained systems; and symptoms intensify through PEM.

This remains a model rather than a settled chain of causation. Researchers are still determining which steps are primary, which are downstream consequences, and which apply only to certain patient subgroups.

What These Findings Mean for Diagnosis and Treatment

The studies show biological differences at the group level, but they cannot yet diagnose an individual. A standard MRI may appear normal even in severe ME/CFS, while advanced MRS, specialized PET scans, spinal-fluid analysis, and effort tasks remain research tools.

No approved medication corrects the reported brain changes or cures ME/CFS. Care is individualized around disruptive symptoms, coexisting conditions, and prevention of PEM.

Practical Management Principles

• Pacing: Balance activity and rest to remain within an individual’s energy limits and reduce crashes.
• Sleep support: Evaluate treatable sleep disorders and use carefully selected behavioral or medical strategies.
• Orthostatic symptom management: Discuss dizziness, rapid heartbeat, faintness, and blood-pressure changes with a clinician.
• Pain and headache care: Use personalized approaches that consider medication sensitivity and overlapping conditions.
• Cognitive accommodations: Shorter tasks, written reminders, reduced sensory load, and scheduled breaks may conserve capacity.

Pacing is not the same as fearfully avoiding all movement, and it is not a promise that perfect planning will eliminate symptoms. It is a strategy for reducing repeated overexertion. Fixed programs that automatically increase exercise can be harmful when they ignore PEM and the patient’s changing limits.

Anyone with new or worsening fatigue should receive a medical evaluation rather than assuming ME/CFS. Urgent care is appropriate for symptoms such as chest pain, severe shortness of breath, fainting, new neurological weakness, confusion, or thoughts of self-harm.

Living With ME/CFS: Composite Experiences Behind the Data

The following examples are composites based on commonly reported experiences. They are not the story of one identifiable person and should not be treated as medical guidance.

The Morning Energy Calculation

Imagine waking after nine hours of sleep and feeling as though the night shift forgot to recharge the building. Before getting out of bed, a person with ME/CFS may calculate the cost of showering, preparing breakfast, answering messages, and attending an appointment. Healthy people also prioritize tasks, but this is different: completing one ordinary activity may remove the capacity for several others.

A shower can combine standing, heat exposure, arm movement, noise, and multiple decisions. Afterward, the person may need to lie down before getting dressed. Friends might see the finished resulta clean, smiling person on a video calland assume the day is going well. They do not see the preparation, the recovery time, or the meal that will later be skipped because the available energy has already been spent.

The Delayed Crash

Another common experience is the deceptive “good day.” A person feels somewhat better and uses the opportunity to shop, clean, socialize, or catch up on work. During the activity, adrenaline and determination may keep things moving. The consequences arrive the next afternoon: heavier limbs, sore throat, headache, disrupted sleep, sensory sensitivity, and brain fog that makes a simple email feel like a tax audit written underwater.

This delay can create self-doubt. The person may wonder whether the activity really caused the crash. Relatives may say, “But you were fine yesterday.” The answer is that yesterday’s exertion can be today’s symptom surge. Recognizing that pattern often requires an activity-and-symptom diary, because memory is not a perfect witnessespecially when cognitive dysfunction is one of the symptoms being tracked.

When Language and Attention Stop Cooperating

Brain fog may involve losing words, forgetting why one entered a room, rereading the same paragraph, or being unable to follow several voices at once. The knowledge is not necessarily gone; access becomes slow and unreliable. A former fast reader may need quiet, large text, and repeated breaks. Someone who once managed complex projects may struggle to complete an online form before the page times out.

These changes can be embarrassing, particularly when other people mistake slowed processing for disinterest or lack of intelligence. Helpful accommodations are often simple: one question at a time, written instructions, fewer interruptions, permission to pause, and meetings scheduled during the person’s more functional hours.

Pacing as a Form of Skilled Adaptation

Over time, many people learn to treat energy as a variable budget rather than a fixed daily allowance. They may sit while preparing food, divide laundry into small steps, use mobility aids, alternate cognitive and physical tasks, or rest before an event rather than only after symptoms become severe. These choices are not surrender. They are practical adaptations to a nervous and metabolic system that does not respond normally to demand.

The emotional adjustment can be substantial. Plans may be canceled. Careers and relationships may change. Improvement, when it occurs, is often uneven rather than cinematic. A meaningful gain might be tolerating a longer conversation, preparing a meal without a crash, or leaving home twice in one week. Those victories may look small from the outside, but inside the energy economy of ME/CFS, they can be major investments paying their first dividend.

Conclusion

Research on chronic fatigue syndrome and brain chemistry has not delivered one tidy answer, but it has produced a more credible map. Exercise-triggered microRNA changes, altered lactate, possible neuroinflammatory signals, immune abnormalities, and disrupted effort-processing networks all suggest that ME/CFS involves measurable biological dysfunction.

The studies are generally small and require replication, so none should be promoted as a standalone diagnostic test or guaranteed treatment target. Still, the practical message is important: post-exertional malaise is real, ordinary rest may not correct it, and care should respect individual energy limits.

As researchers connect molecular signals with symptoms and patient subtypes, the goal is not merely to prove that people are ill. It is to help them receive earlier diagnoses, more precise treatments, and basic human belief without having to present a PowerPoint defense of their own nervous system.