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Mild Cognitive Impairment (MCI) is a diagnosis, not a root cause.

What Causes Mild Cognitive Impairment (MCI)?

What Causes Mild Cognitive Impairment (MCI)?

Mild Cognitive Impairment, or MCI, is a diagnosis. It is not a root cause. MCI means that measurable changes in memory, thinking, processing speed, or cognitive function have been identified. However, those changes are not yet severe enough to meet the criteria for dementia. Therefore, the most important question is not simply, “Do I have MCI?”  The more important question is, “Why is this brain struggling?”

At the Carroll Institute in Sarasota, Florida, we evaluate Mild Cognitive Impairment, early Alzheimer’s disease, and cognitive decline using the Carroll Cognitive Method™. A personalized approach that combines Precision Medicine, Functional Medicine, and Functional Neurology.

Mild Cognitive Impairment Is Often Misunderstood

Many people believe that once they receive a diagnosis of Mild Cognitive Impairment, they have also received an explanation for what is causing their memory problems.

That is not true.

MCI describes what is happening. It does not explain why it is happening.

Think of MCI like the check engine light in your car. The warning light tells you there is a problem. It does not tell you whether the problem is the battery, the fuel pump, the alternator, or the transmission.

The same is true with memory loss. The diagnosis tells us that the brain is struggling. It does not tell us why.

What Is Mild Cognitive Impairment?

Mild Cognitive Impairment is a stage of cognitive decline that falls between normal age-related forgetfulness and dementia. People with MCI may still function independently, but they begin noticing changes that are more frequent or more significant than typical forgetfulness.

  • Increasing forgetfulness
  • Difficulty finding words
  • Reduced concentration
  • Slower processing speed
  • Trouble learning new information
  • More reliance on notes, calendars, or reminders
  • Repeating questions or conversations

These symptoms should not be dismissed as “just aging.” Memory loss may be common, but that does not mean it is normal.

MCI and Early Alzheimer’s Disease Often Share the Same Root Causes

Patients often ask whether the same approach applies to both Mild Cognitive Impairment and early Alzheimer’s disease.

In many cases, yes.

The diagnosis may differ, but the underlying question remains the same: why is this brain struggling?

Whether a person has MCI, early Alzheimer’s disease, or progressive cognitive decline, the contributing factors may include inflammation, insulin resistance, sleep apnea, hormonal changes, vascular dysfunction, nutritional deficiencies, environmental toxins, or weakened brain networks.

Common Causes of Mild Cognitive Impairment

Mild Cognitive Impairment rarely has one single cause. In many patients, several contributors are occurring at the same time.

1. Chronic Inflammation

Inflammation is one of the most important drivers of cognitive decline. Chronic inflammation may affect memory, attention, processing speed, and overall brain performance. Neuroinflammation is also increasingly recognized as an important factor in Alzheimer’s disease and MCI.

2. Insulin Resistance and Blood Sugar Problems

The brain requires enormous amounts of energy. When insulin resistance or blood sugar dysfunction interferes with energy production, the brain may struggle to function properly. This is why some researchers have described Alzheimer’s disease as involving impaired brain metabolism.

3. Sleep Disorders

Sleep apnea and poor sleep quality are among the most overlooked contributors to memory loss. During sleep, the brain performs critical repair, recovery, and memory-processing functions. A brain that does not sleep well cannot recover well.

4. Vascular Dysfunction

The brain depends on healthy blood flow and oxygen delivery. Vascular problems may contribute to slower thinking, memory problems, and reduced executive function.

5. Hormonal Imbalances

Hormones influence memory, mood, sleep, energy production, and brain function. Thyroid dysfunction, sex hormone changes, and stress hormone disruption may all contribute to cognitive symptoms in some patients.

6. Nutritional Deficiencies

The brain requires specific nutrients to function properly. Deficiencies in vitamins, minerals, fatty acids, and other nutrients may affect cognition, energy production, and neurological function.

7. Environmental Toxins

Mold exposure, heavy metals, pesticides, air pollutants, and other environmental toxicants may contribute to inflammation and cognitive symptoms in susceptible individuals.

8. Brain Network Dysfunction

Even when biological contributors are addressed, the brain still has to function. Memory, language, balance, attention, and processing speed depend on healthy brain networks. Functional Neurology helps evaluate and rehabilitate those networks.

Why Every Patient With MCI Is Different

One patient may have insulin resistance and sleep apnea. Another may have inflammation and hormonal imbalance. Another may have mold exposure, vascular dysfunction, and weakened brain networks.

All three patients may receive the same diagnosis: Mild Cognitive Impairment.

But the reasons their brains are struggling may be completely different.

This is why one-size-fits-all approaches often fall short. The treatment strategy should match the person, not just the diagnosis.

What the EVANTHEA Precision Medicine Trial Supports

The EVANTHEA Precision Medicine Trial supports the idea that cognitive decline should be addressed through a personalized, systems-based approach rather than a single-target strategy.

Instead of focusing on only one factor, the EVANTHEA approach evaluated and addressed multiple contributors, including metabolism, inflammation, sleep, nutrition, exercise, hormones, stress, and cognitive stimulation.

This is important because MCI and early Alzheimer’s disease are rarely driven by only one issue. The more accurately we identify the contributors, the more opportunities may exist to support cognitive performance.

The Carroll Cognitive Method™ Perspective

At the Carroll Institute, we do not stop at the diagnosis of MCI.

We ask a deeper question:

Why is this brain struggling?

The Carroll Cognitive Method™ combines three key disciplines:

Precision Medicine

Precision Medicine helps identify the specific contributors affecting each individual patient’s brain health.

Functional Medicine

Functional Medicine helps address root causes such as inflammation, metabolic dysfunction, sleep issues, hormonal imbalance, nutritional deficiencies, and environmental exposures.

Functional Neurology

Functional Neurology evaluates how the brain is functioning and uses targeted rehabilitation strategies to support neuroplasticity and improve brain network performance.

Why Early Investigation Matters

Early investigation matters because cognitive decline often progresses when the underlying contributors are not addressed.

Waiting rarely creates more options. Acting earlier often does.

A diagnosis of MCI should not be treated as a passive waiting room before dementia. It should be treated as a signal that the brain needs a deeper investigation.

Can MCI Be Improved?

For many patients, improvement may be possible when the factors driving cognitive decline are identified and addressed. No ethical clinician can guarantee outcomes, and every patient is different. But MCI should not automatically be viewed as inevitable decline.

The better question is not simply whether MCI can improve.

The better question is:

What is preventing this brain from functioning better?

Who Should Consider a Comprehensive Evaluation?

You may benefit from a comprehensive cognitive evaluation if you:

  • Diagnosed with Mild Cognitive Impairment
  • Have early Alzheimer’s disease
  • Notice increasing forgetfulness
  • Persistent brain fog
  • Difficulty finding words
  • A family history of dementia
  • Feel less mentally sharp than before
  • Want a proactive assessment of brain health

Next Steps

Mild Cognitive Impairment is important, but it is only the beginning of the conversation.

The diagnosis tells us that the brain is struggling.

It does not tell us why.

At the Carroll Institute, our goal is to identify the factors affecting brain health and develop a personalized strategy designed to support cognitive performance.

If you or someone you love has been diagnosed with Mild Cognitive Impairment, early Alzheimer’s disease, or worsening memory problems, consider scheduling a discovery phone call with the Carroll Institute to learn whether the Carroll Cognitive Method™ may be appropriate for you.

Sources

Medical Disclaimer

This information is provided for educational purposes only and is not intended as medical advice. Individual outcomes vary. Patients should consult a qualified healthcare professional regarding their individual medical situation.

Reviewed by: Dr. Garland Glenn, DC, PhD, IFM, AFMC

Location: Sarasota, Florida

Last Updated: June 19, 2026

Dr. Garland Glenn, DC, PhD, IFM, AFMC

Founder & Clinical Director, The Carroll Institute — Sarasota, FL

Dr. Garland Glenn is a board-certified chiropractic physician and functional medicine practitioner specializing in cognitive health, neurodegeneration, and root-cause medicine. Certified as an AFMC (Advanced Functional Medicine Clinician) and Institute for Functional Medicine (IFM) trained. He has also completed over 500 hours of advanced training in Functional Neurology under Dr. Ted Carrick, founder of the Carrick Institute.

At The Carroll Institute, Dr. Glenn leads Sarasota’s only ReCODE-certified Functional Neurology program, helping patients reverse or prevent cognitive decline through the Bredesen ReCODE Protocol, neuroplasticity exercises, and personalized functional medicine care.

Learn more about his background and approach at About Dr. Garland Glenn.

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ReCODE® is a registered program developed by Dr. Dale Bredesen and licensed through Apollo Health. Dr. Garland Glenn is a certified ReCODE practitioner.

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