Environmental Health Update

Mercury – Neurotoxicity and Memory

Marianne Marchese, ND

Introduction

As we age, we expect some cognitive decline, but at what point is it considered problematic? For most people, a decline in short-term memory is mild and doesn’t interfere with daily functioning. For others it can be an early sign of more serious cognitive changes such as dementia or Alzheimer’s disease. When someone says they forget things easily or don’t recall where they put their keys, it may or may not indicate neurocognitive decline. For most individuals, poor memory may be attributed to a lack of attention to detail, information overload, or stress. For some it may be due to a change in hormones, nutrient deficiencies, or sleep deprivation. Of course, it may be a sign of a more serious medical condition that should not be overlooked. Exposure to environmental toxicants can also play a role in poor short-term memory. Exposure to toxicants such as mercury can cause neurotoxicity and cognitive changes at any age. When evaluating someone for concerns about changes in short-term memory, there are many factors to explore and tests to run. This article will focus on the effects of mercury exposure as an often-overlooked link to cognitive decline.

Mercury

There are three forms of mercury that people are exposed to in their everyday life, often without knowing they are exposed. Elemental mercury is found in mercury-containing coal, thermometers, fluorescent bulbs, dental amalgam fillings, and latex paints. It eventually enters vapor state and is absorbed through the lungs. It is very lipophilic and accumulates in the brain and kidney. Organic mercury is another form of mercury and is present as methylmercury or ethylmercury. Most methylmercury exposure comes from dietary fish and poultry whereas ethylmercury used to be in vaccines and some antiseptics. Methylmercury, the most toxic form to humans, bioaccumulates in the tissues, crosses the placental and blood brain barrier, and is formed from the conversion of inorganic or elemental mercury in living organisms. It may be found in water and soil as the result of the methylation of elemental and inorganic mercury by microorganisms. It is lipophilic and accumulates in the brain and kidney. Inorganic mercury present as mercury salts is found in cosmetic products like skin-lightening creams and face creams, laxatives, teething powders, diuretics, and antiseptics. It also is formed from the metabolism of elemental mercury vapor or methylmercury. Inorganic mercury is water soluble and does not cross the blood brain barrier.^1,2

Memory

Several studies show a link between mercury exposure, neurotoxicity, and memory. Methylmercury neurotoxicity was first discovered in adults with acute poisoning.³ Later it was discovered that it can cross the placental barrier and affect the cognition and development of children exposed in-utero. It is known that eating fish is the main source of exposure of methylmercury, and studies show children in fishing populations experience developmental neurotoxicity.⁴ The developing brain is more susceptible to the effects of methylmercury. Prenatal mercury exposure is a concern not only for the mother but also for the neurocognitive development of her offspring. It is well documented that in-utero methylmercury exposure from seafood consumption may lead to neurological alterations, including cognitive and motor dysfunction.⁵

Adults are affected by mercury exposure as well and can cause neurotoxicity signs and symptoms. High dose exposure can cause loss of neuronal cells in specific brain regions, such as the visual cortex and the cerebellum as seen on brain MRI.⁵ As people age and memory declines, concerns of dementia and even Alzheimer’s disease arises. Given the fact that mercury is a neurotoxin studies have looked at its links to Alzheimer’s disease, AD. Known changes in AD include plaques, beta amyloid protein, neurofibrillary tangles, phosphorylated tau protein, and memory loss; all of which can be caused by mercury exposure.⁶ Patients diagnosed with Alzheimer’s disease exhibit higher levels of brain mercury and blood mercury. One study showed that in early onset AD patients blood mercury levels were almost three-fold higher as compared to controls.⁷ A cross-sectional analysis of deceased patients in the Memory and Aging Project cohort study, conducted 2004–2013, showed seafood consumption was also correlated with higher brain levels of mercury; however, the higher brain concentrations of mercury were not significantly correlated with increased levels of brain neuropathology.⁷ Fish consumption can provide essential nutrients that can be protective of cognitive decline such as essential fatty acids. It is advisable that adults continue the benefits of seafood consumption and at the same time avoid fish known to be high in mercury. A simple blood test for mercury can help determine if a patient’s seafood consumption is creating elevated mercury levels in the body.

Other forms of mercury besides methylmercury from fish have been linked to changes in memory. A study of occupational exposure to elemental mercury showed a clear link to mild changes in short-term memory.⁸ Changes in short-term memory was assessed through standardized cognitive tests in workers employed at mercury cell chlor-alkali plants. It was found that exposure to elemental mercury on the job was associated with higher urinary mercury levels and poor short-term memory. Most studies on elemental mercury and poor memory come from occupational sources of exposure.

In general practice poor short-term memory is a common complaint amongst older adults. Although there is a link with mercury and Alzheimer’s disease, most patients will be experiencing milder forms of cognitive decline such as poor short-term memory. A link to mercury can be a contributing factor. There are several studies linking mild memory impairment in adults to fish intake. One study used hair analysis to link elevated mercury from fish consumption in adults with memory decline.⁹ Although hair analysis was used in this study, the preferred method for detecting methylmercury from fish in the body is blood test. Assessing for mercury exposure should be included in all patient with complaints of poor memory. Below is a case example.

Case

At the end of 2018, a 56-year-old woman who has been managed for surgical menopause with hormone replacement therapy returned with new complaints of fatigue and poor memory. Her neurological and physical exam were normal, and she had no other neurological symptoms. She said the memory concerns were poor short-term memory such as forgetting where she put something or walking into a room to get something and forgetting why. Her long-term memory was fine, and she had no changes in orientation, alertness, speech, thinking, comprehension, or word-finding. Her poor memory didn’t interfere with her work or activities of daily living. Upon further questioning she described it as more of a brain fog and forgetfulness. She has no headaches or dizziness. She smokes cigarettes, a half pack daily for over 20 years. She eats fish two-to-three times a week, including tuna and swordfish. She is healthy other than she has osteoarthritis and joint pain in hands and knees. She is up-to-date on screening exams such as mammogram, pap smear, dexa scan, and colonoscopy; and all are normal. She sleeps well every night (7-8 hours), exercises regularly, and eats well. Her stress is low, and she feels emotionally balanced.

Her current supplements and medications include the following: vitamin D3 (5,000 IU a day), joint formula with glucosamine chondroitin, DHEA (5 mg once a day), HRT troche biest (2.5 mg/Prog 50 mg/test 3mg).

Labs and imaging were ordered, which included brain MRI without contrast (normal), CBC (normal), TSH (2.0), E2 (18), CMP (normal), lipid panel (normal), testosterone (25), B12, iron and vitamin-D ( all normal), DHEA 285 (high),

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lood mercury 29 (high).

Patient was told to lower DHEA to 5 mg every other day and stop eating all fish and make appointment for a chelation/detoxification plan. Patient was also told to stop smoking and offered help and a referral to a smoking cessation program.

In January 2019, she decided to retest the mercury levels before making a follow-up appointment to begin chelation. The mercury lowered to 14, which is still elevated. Note: the mercury lowered from 29 to 14 without chelation and just by avoiding fish only. She said she had not stopped smoking yet. The chelation/detoxification plan included a detox diet, supplements, and chelation:

Detox Diet (organic and non-GMO)

1. 1 Tbsp ground flax seeds/meal a day on food

2. 1 teaspoon of psyllium husk powder in water

3. 3-4 cups of green tea

4. No red meat

5. Increase legumes, fruits, veggies

6. No sugar, no artificial sweeteners

7. 3-4 servings of cruciferous veggies a day

8. No cow milk products

9. Fish low in mercury is okay

10. Lean meats are okay, such as chicken, turkey, wild game

11. Protein – 20 grams three times a day= 60 grams a day

12. Nuts and seeds are good

13. Complex carbohydrates like quinoa and brown rice are okay

14. No simple carbohydrates; breads, pasta, bagels, tortilla

Supplements for Two Months

1. N-Acetyl Cysteine (NAC; 600 mg twice a day)

2. Cofactor support product (6 capsules/day, which contained vitamin A, vitamin D3, vitamin K1, vitamin B-1, vitamin B-2, vitamin B-3, vitamin B-5, vitamin B-6, vitamin B-12 (as methylcobalamine), vitamin C, vitamin E, biotin, folate (5-methyl-tetrahydrofolate), calcium, chromium, copper, iodine, magnesium, manganese, molybdenum, potassium, selenium, zinc, choline, inositol, boron, vanadium, green tea extract, turmeric)

3. Liver herbal support product, which consisted of milk thistle, beet root, dandelion, burdock and artichoke.

Chelation for Six Weeks

1. Oral DMSA (200 mg capsules). She took one capsule three times a day (6 hours apart) three days in a row then did not take it for 11 days. This equals one round, or two weeks. She repeated this process two times for a total of three rounds, which lasts six weeks.

2. Sauna Therapy. Start with 10 minutes in hot sauna, 30-second cold rinse. Repeat five times and end on cold. Do this one-to-two times a week for 10 sessions

Three months later the blood mercury dropped to 5. It started at 29, dropped to 14 by avoiding all fish, and then dropped to 5 with the chelation and detoxification plan. She is still smoking two cigarettes a day. Her memory is subjectively better, and she feels like she no longer has short-term memory concerns. Her joint pain and fatigue resolved completely. She was told to continue the NAC, cofactor support, avoid fish high in mercury, and stop smoking. She was sent to a local smoking cessation program.

Summary

Poor short-term memory or changes to memory are often a subjective complaint of patients as they age. There are numerous causes of cognitive decline that need to be evaluated for in patients presenting with this concern. Environmental toxicants such as exposure to mercury are often overlooked. It is important when working up a patient for changes in memory that all factors be explored. This includes testing for metals in the body, especially mercury as it is linked to both mild cognitive decline and Alzheimer’s disease. Chelation along with detoxification support is an effective method of removing metals from the body once the source of exposure is identified and eliminated. By removing the mercury from the body, patients may have an improvement in memory and other health concerns.

References

1. Marchese, M. 8 Weeks to Women’s Wellness. Petaluma, CA. Smart Publications 2011.

2. Crinnion WJ, Pizzorno JE. Clinical Environmental Medicine. St Louis, MO. Elsevier 2019.

3. Grandjean, P, Herz KT. Methylmercury and Brain Development: Imprecision and Underestimation of Developmental Neurotoxicity in Humans. Mt Sinai J Med. 2011; 78(1): 107–118.

4. Choi AL, Grandjean P. Methylmercury exposure and health effects in humans. Environmental Chemistry. 2008;5:112–120.

5. Antunes Dos Santos A, et al. Methylmercury and brain development: A review of recent literature. J Trace Elem Med Biol. 2016;38:99-107.

6. Siblerud R, et al. A Hypothesis and Evidence That Mercury May be an Etiological Factor in Alzheimer’s Disease. Int J Environ Res Public Health. 2019;16(24):5152.

7. Hock C, et al. Increased blood mercury levels in patients with Alzheimer’s disease. J Neural Transm (Vienna). 1998;105(1):59-68

8. Smith PJ, Langolf GD, Goldberg J. Effect of occupational exposure to elemental mercury on short term memory. Br J Ind Med. 1983;40(4):413-419.

9. Yokoo EM, et al. Low level methylmercury exposure affects neuropsychological function in adults. Environ Health. 2003;2(1):8. 

Bio

Dr. Marianne Marchese is the author of the bestselling book 8 Weeks to Women’s Wellness about the environmental links to women’s health and how to detoxify from toxicants. She maintains private practice in Phoenix, Arizona, and is adjunct faculty at SCNM, teaching both environmental medicine and gynecology. She served on the State of Arizona Naturopathic Physicians Medical Board

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National Association of Environmental Medicine, Arizona Naturopathic Medical Association, and Council on Naturopathic Medical Education. Dr. Marchese has helped formulate supplements for Priority One Vitamins. She lectures throughout the US and Canada on women’s health, environmental, and integrative medicine topics. www.drmarchese.com