As you may already know, the thyroid impacts nearly every system in the body by coordinating and producing various hormones. Of critical importance is its effect on the brain.
Currently we are aware of symptoms such as anxiety, reduced cognitive function, and depression that commonly accompany thyroid conditions such as hypothyroidism and hyperthyroidism. These are widely accepted as being reversible through proper treatment and hormone replacement therapy. However, recent studies suggest that the thyroid may be more closely linked with irreversible brain diseases, such as Alzheimer’s, than previously thought.
What is Alzheimer’s?
Alzheimer’s Disease is a neurodegenerative condition that is incurable and currently unpreventable. Sadly, the only FDA-approved medications for treatment of Alzheimer’s simply delay symptoms for about 6 to 12 months and only in about 50% of individuals.
This condition is officially rated as the 6th most prominent cause of death in the U.S. with over 5 million Americans afflicted. However, new numbers suggest that due to the increasing death-rate due to Alzheimer’s it may have advanced up into the third most frequent cause of death resting just under heart disease and cancer.
As the primary causal factor of dementia, we would expect there to be significant and easily recognizable symptoms of this condition. Regrettably, the indicators of damage for this disease move at such a slow rate that it is commonly overlooked. If you’re lucky, symptoms can be recognized early. Some of the most common identifiers of Alzheimer’s include but are not limited to:
- Memory Loss (usually short-term memory)
- Difficulty Speaking
- Difficulty Utilizing Language
- Mood Swings
- Behavioral Volatility
- Difficulty doing Simple Tasks (ex. eating, walking, talking)
Unfortunately, these telltale signs are either missed entirely or incorrectly correlated to natural aging. This condition is usually only recognized after the patient has had it for 10-20 years. At that point it is usually too late to react as nerve cells and brain tissue have been irreparably damaged and destroyed. Ultimately this causes brain shrinkage and continually reduces overall brain functionality.
Making the Connection
In July of 2008 the article “Thyroid Function and the Risk of Alzheimer’s Disease: The Framingham Study” was published in the medical journal Archives of Internal Medicine. This study presented a great deal of interesting data, but of primary interest was the association that was discovered between TSH (thyroid stimulating hormone) levels and the risk of Alzheimer’s in women. Data suggests that women who fall outside a specific TSH level are at greater risk of developing Alzheimer’s disease. This relationship was not reflected in male participants.
The 2008 study utilized data provided by the original Framingham Study, a long-term research project that began in 1948 in which participants are biennially examined for cardiovascular risk and developing cardiovascular disease. After 1982 participants of the Framingham Study were administered a larger range of tests including numerous neuropsychological tests including the Mini-Mental Status Examination (MMSE) to test for dementia. Importantly, participants also had their TSH levels tested in a way that allowed for the data to be utilized in the more recent study. Observation of participants over extended periods (follow-up rate of 12.7 years) allowed for comparing TSH serum levels in relation to irreversible neurological conditions such as Alzheimer’s and dementia.
Regardless if the patient was taking thyroid medication, data on TSH ranges and Alzheimer’s occurrence remained the same. Because the study was observational in nature, only suggestions can be made as to the causal effect of TSH levels on this neurological condition. One hypothesis is that as a regulator of Amyloid Precursor Protein (APP), a gene that may be partly responsible for inducing Alzheimer’s, TSH levels may have a direct impact on the prevalence of Alzheimer’s. Improper regulation of APP due to exceptionally high or low TSH levels could lead to this neurodegenerative disease.
Unfortunately, it is not entirely clear whether TSH levels are causing Alzheimer’s or if Alzheimer’s is impacting the thyroid in a way the changes TSH levels. However, during the observation process of about 13 years 209 of the observed 1,864 individuals developed Alzheimer’s Disease. A correlation was found between the occurrence of Alzheimer’s and women whose TSH levels fell below 1.0 or had levels that remained above 2.1. Those that did not maintain levels in this range were more than twice as likely to develop Alzheimer’s. This is highly disconcerting as that is a small range. In addition, current standards suggest that a healthy range for TSH levels is anywhere between 0.5 and 5.0. It is common for treatment to be based off of this larger number set even though they clearly fall outside the range suggested by the above data suggested by the study.
Protect Your Brain by Protecting Your Thyroid
With optimal TSH levels still being debated it can be disheartening to hear that studies are beginning to show many people may be improperly treated leading to a devastating condition later in life. But, with this new information, perhaps standardized TSH ranges can be modified and updated to more conservative numbers. In fact, the American Association of Clinical Endocrinologists (AACE) proposed a narrowing of ranges to 0.3 to 3.0 as opposed to the current range of 0.5 to 5.0. Unfortunately, this decision was not finalized. But the National Association of Clinical Biochemistry pushed even further. Suggesting that the high end of the spectrum should be no greater than 2.5 for TSH levels.
Although it is best not to gauge your thyroid health and treatment based solely on TSH levels, this data is still useful and may be of critical importance later in life. Sadly, there are those whose treatment is forced outside of the more conservative TSH ranges due to conditions such as thyroid cancer, where treatment commonly includes using thyroid hormone disruptors to keep TSH levels low.
As always, in regards to the thyroid, it is best to get a complete picture, but TSH may now have greater value when considering the data. Awareness of and maintaining good thyroid health not only helps you live a better life now, but may in fact prevent a tragic condition in the future.