Thyroid Function and the Risk of Alzheimer’s Disease: A Mendelian Randomization Study
Our longitudinal model addresses that concern and may, therefore, add support to their conclusions. However, unlike these studies, ours relied on self-reported diagnosis of thyroid disease instead of more objective diagnostic methods, and is therefore not directly comparable. Our findings, coupled with the uncertainty of past research, make the relationship between thyroid dysfunction and AD one of continuing interest for future study. A review of recent literature reveals inconsistency concerning the impact of thyroid dysfunction on cognitive decline.
Actor Gene Hackman died of heart disease a full week after his wife died from hantavirus in their New Mexico hillside home, and he may not have been aware she was dead because he showed severe signs of Alzheimer’s disease, authorities revealed Friday. Both drugs cost more than $25,000 a year, and then there’s all the PET and MRI imaging. The memory and thinking problems should also be new and persistent (not just occasional lapses), Dr. Schindler says. If someone who was always on point suddenly starts missing appointments or mixing up dates repeatedly, that’s a red flag. Still, she says, “For the right patients, I do think these treatments are worth it.” Read on to learn more about these revolutionary drugs and if they may be right for you or a loved one. Two-tailed analyses were conducted, and P values less than 0.05 were considered to indicate a statistically significant difference.
- Our study attempts to help fill this research void by examining possible associations between use of thyroid medications and AD onset.
- In a newly published study, hyperthyroidism exacerbates cognitive impairments and increases the accumulation of βA plaques in mice by the activation of neuroinflammation and the induction of brain tissue necroptosis via the RIPK3/MLKL pathway (50).
- In the first study exploring the hypothalamic-pituitary-thyroid axis in AD, the levels of TRH, TSH and TH were significantly lower in patients with AD (30).
- I strongly believe so, and even the authors do suggest that the dose of thyroid hormone that you are taking may play a role.
- The high oxidative stress in Alzheimer’s patients also decreases DIO2 activity and increases DIO3 activity (36).
Comparison with other studies
In either event, this can stem from how your body processes and attempts to break down the medication. We also know that patients with Alzheimer’s have low levels of T3 (2) (even within the normal range), indicating the importance of this hormone over other hormones such as Free T4. It is well known that hypothyroidism can mimic Alzheimer’s disease and it is something that should be evaluated and treated in all patients with dementia. This connection has led some researchers to believe that thyroid medication is the thing CAUSING dementia in these people. There’s no rule against going on the drugs if you carry two copies of APOE e4, Dr. Lapins says. But at her center they’ve decided not to offer the treatment to those patients for now.
Characteristics of Participants
Input-output connections and LTP of the perforant pathway were greatly reduced in animals with hypothyroidism, and the ability of synapses between the perforant pathway and the dentate gyrus to undergo LTP was significantly impaired (70). An increasing body of evidence suggests a strong link between thyroid dysfunction and Alzheimer’s disease (2, 3). Additionally, we propose a concept of a “vicious circle” to describe this relationship, highlighting the reciprocal influence between the two conditions. We anticipate that these findings will lay the foundation for the creation of individualized and innovative treatment approaches for individuals who are impacted by AD. Hyperthyroidism is reported to affect DAT risk in older adults as well, such that increased levels of T4 and free T4 increase one’s risk of developing DAT (de Jong et al., 2007; Kalmijn et al., 2000; Tan et al., 2008).
However, it remains unsatisfactorily investigated whether TH transport is impaired in AD. First, the mechanism of MCT1 downregulation during AD pathology is uncertain as to whether it applies to MCT8 or MCT10. Second, the role of TTR in maintaining TH concentrations in the brain is controversial. Hence, we are looking forward to further studies on TH transport during AD pathology. However, studies on the relationships between thyroid diseases and Alzheimer’s disease (AD) have reported conflicting results.
- Hantavirus typically is reported in spring and summer, often due to exposures that occur when people are near mouse droppings in homes, sheds or poorly ventilated areas.
- None of the patients had a diagnosis of cognitive decline or a low TSH level within six months of their first provider visit.
- Third, since information about serum thyroid hormone levels and thyroid gland function were not available in the claims database, we could not consider them in this analysis.
- We performed a sensitivity analysis to examine the robustness of our findings by excluding one study at a time and recalculating the pooled estimates.
- An experimental study found a 5% increase in GABA levels after a 6-month treatment with LT-4 and a positive correlation of GABA in the medial prefrontal cortex with memory function 17.
This suggests to us that the autophagy pathway may be overwhelmed by the accumulation of oxidative stress and cellular damage, resulting in relative autophagic insufficiency. How to effectively regulate autophagic activity may become a potential treatment for AD and other neurodegenerative diseases. Thyroid dysfunction has been implicated as a cause of reversible cognitive impairment and as such, the thyroid stimulating hormone has long been part of the screening laboratory test for dementia. Recently, several synthroid invention population-based studies demonstrated an association between hypo- or hyperthyroidism and Alzheimer’s disease. This review discusses the role of thyroid hormone in the normal development and regulation of central nervous system functions and summarizes the studies that have linked thyroid function and dementia risk.
Exclusion criteria included medical, psychiatric, and neurological illnesses that may interfere with performance on psychometric testing or longitudinal follow-up (e.g., uncontrolled diabetes, renal failure requiring dialysis, treatment for active invasive cancer). Stopping your thyroid medication will cause hypothyroidism which may only further increase your risk of dementia. We know that people taking thyroid medication do indeed seem to have an increased risk of developing dementia long-term. As most primary studies analyzed reported different cutoffs of TSH, we further performed a dose–response meta-analysis. A total of 11 studies (6, 7, 10, 11, 13, 21, 24, 25, 26, 27, 28) containing 46,417 individuals with more than three categories of TSH concentrations were analyzed. Dementia is a progressive disease with declining cognitive function and affects daily activities (1).
This might be someone who has trouble remembering appointments, dealing with finances, or recalling familiar words, for example, but can mostly manage daily life independently. Dr. Lapins says many of her patients are still driving and going food shopping—and some are still working. Administered through a needle placed in an arm vein, these medications are lab-made antibodies designed to find and latch on to amyloid in the brain. Once they do, they act like a warning siren to specific immune system cells so they can swoop in and destroy the enemy, which slows down the worsening of people’s symptoms. For a long time, researchers have thought that if they could find a way to sweep amyloid from the brain before a person develops more severe Alzheimer’s symptoms, they might be able to slow the progression of the disease. These drugs work by clearing amyloid from the brain, which doctors can see on specialized imaging called a PET brain scan.
How to Increase Free T3 Without Thyroid Medication
It is worth noting that these aforementioned influences do not exist in isolation, but rather interact and mutually affect each other. And we must emphasize the lack of convincing conclusions between hyperthyroidism and AD. These concurrent mechanisms may all be involved in the pathogenesis of Alzheimer’s disease (Figure 2).
The strengths of the present study involved the numerous participants who were recruited from a representative, nationwide population sample and the detailed information regarding the various covariates adjusted as confounding factors in the analyses. Thus, we were able to adjust for plausible confounding factors and perform stratified subgroup analyses to identify potentially relevant interactions. Although the diagnosis of AD was based on ICD-10 coding, the coding of AD from NHIS data had good accuracy and validity, as described in our previous literature (18, see File S2). We calculated the interaction for each relationship between the independent variables and basic demographics including age, sex, income, and region of residence in model 2 (Table S3). The last strength of the present study is that this work simultaneously addresses hypothyroidism and hyperthyroidism in a single study and includes adjustment for previously undisclosed factors, such as each thyroid disease and thyroid medication (levothyroxine). Nevertheless, there are some limitations to our analysis that warrant consideration.