A common thyroid disorder, called “hypothyroidism”, could lead to Alzheimer’s disease.
- This work is observational: it shows a correlation, but not a causal link.
- The study did not take into account the severity of hypothyroidism.
- The frequency of hypothyroidism increases after 65 years.
Alzheimer’s disease is complex and has multiple causes. According to a study published on July 6 in Neurology, it could be linked to another pathology: hypothyroidism. This disorder corresponds to an inability of the thyroid gland to produce enough hormones. L’Health Insurance specifies that it isresponsible for physiological and psychological disturbances” : fatigue, weight gain, slow heart rate, decreased sweating, cramps, etc.
Hyperthyroidism or hypothyroidism?
To understand the links between the two diseases, the research team analyzed the medical records of more than 7,800 people, recently diagnosed with dementia, in Taiwan. They compared these records to those of people who did not suffer from it. Scientists are also interested in people affected by hyperthyroidism, when the thyroid produces too many hormones. “Symptoms include unintentional weight loss, rapid or irregular heartbeat, nervousness or anxiety”, they point out. Of all the files analysed, 102 people suffered from hypothyroidism and 133 from hyperthyroidism.
A high risk
The researchers found no link between hyperthyroidism and dementia. In contrast, 0.9% of people with dementia also had hypothyroidism, compared with 0.4% of those without. Taking into account other risk factors, such as age, sex, hypertension and diabetes, researchers found that people over 65 with hypothyroidism were 80% more likely to develop dementia, compared to people of the same age who do not have a thyroid problem. This observation is not valid for people under 65 years of age.
Treatments exist
In a second step, the researchers compared the levels of risk in people taking treatment against hypothyroidism and those not having it. They noticed that they were three times more likely to develop dementia, compared to others. “One possible explanation is that these people are more likely to have more severe symptoms of hypothyroidism, as treatment is needed.“, emphasizes Chien-Hsiang Weng, the author of the study. He also adds that the symptoms of dementia are not necessarily incurable. “In some cases, thyroid disorders have been associated with symptoms of dementia which may be reversible with treatmentsays Chien-Hsiang Weng. Although more studies are needed to confirm these results, people should be aware that thyroid problems are a possible risk factor for dementia..”
