Thyroid disorders are the most common hormonal issues that affect young people. Hormones produced by the thyroid gland (T3 and T4) play a major role in maintaining the normal metabolic activities of the body. Thus, any impairment in the production of these hormones can be detrimental to one’s health.

In this blog post, we shall focus on the early stages of an underactive thyroid gland (hypothyroidism), when symptoms haven’t presented themselves yet, in order to find out how this condition can affect memory and thinking processes.

Subclinical hypothyroidism

Hypothyroidism can remain asymptomatic for many years and can affect numerous organs before it is diagnosed. In the early stages, as the thyroid gland’s ability to produce thyroid hormones is reduced, the brain releases more thyroid stimulating hormone (TSH) to stimulate the thyroid gland to produce more thyroid hormones.

Therefore, subclinical hypothyroidism is characterized by normal thyroid hormone and elevated TSH levels. As the disease progresses, eventually thyroid hormone levels become low along with severely elevated TSH levels and is then termed as “Clinical Hypothyroidism”.

The most common cause of hypothyroidism is the autoimmune condition, Hashimoto’s disease (also known as Hashimoto Disease, Hashimoto Syndrome or Hashimoto thyroiditis).

Cognitive deficits in “Clinical” Hypothyroidism

Changes in the anatomy of the brain have been found as a result of decreased thyroid hormone levels. This could explain why cognitive deficits exist in patients known with hypothyroidism.

Many hypothyroid patients report some sort of cognitive deficits, which range from attention or memory problems, to a decrease in intelligence or difficulty with language. Most of the issues are related to deficiencies in short-term memory, but some patients also reported experiencing symptoms of depression.

These effects have been noted to worsen with age and older patients seem to suffer the worst cognitive defects. It is also suggested that a link exists between excessive levels of TSH and the development of Alzheimer’s disease.

Unfortunately, even if these patients are treated appropriately, they may never completely regain normal cognitive functioning.

Cognitive deficits in “Subclinical” Hypothyroidism

Interestingly, patients who have subclinical hypothyroidism can still present with symptoms of cognitive dysfunction.

There are patients diagnosed with subclinical hypothyroidism who would commonly complain of issues such as a slowed thinking process and memory loss.

Even though cognitive deficits in elderly patients could be due to other issues such as adverse effects of medication or due to chronic illnesses, thyroid disorders would still need to be excluded and therefore appropriate tests should be performed.

Patients who are diagnosed with subclinical hypothyroidism can benefit from thyroid replacement therapy.

How can you find out that your memory problems are due to hypothyroidism?

One needs to be sure of the diagnosis of hypothyroidism. TSH values can fluctuate throughout the day; therefore doctors will need to repeat thyroid function tests after at least 3 months in order to confirm the diagnosis.

Treatment with the thyroid hormone T4 (levothyroxine, trade name Synthroid) is usually started when TSH values are elevated past a certain level. It is recommended that thyroid hormone replacement can be started in younger patients who have mild-subclinical hypothyroidism, and who present with symptoms of mild memory impairment and mood problems.

It’s also suggested that no benefits exist in treating patients with subclinical hypothyroidism, who are over 65 years of age.


Cognitive impairment is common and can affect a person’s quality of life. Subclinical hypothyroidism is also very common and may go undetected for many years.

Not all memory problems occur due to subclinical hypothyroidism, but can rather be an unrecognized underlying factor.

It’s therefore important to be aware that hypothyroidism can affect memory and thought processes so that any complaints of these issues can be discussed with the patient’s doctor.

Author Bio:

Sameer Ather MD, PhD is a Cardiologist based out of Birmingham, Alabama and is also the co-founder and CEO of website www.xpertdox.com, which is designed to help patients suffering from rare or serious diseases. His current research focus is to identify heart failure patients who do not benefit from beta-blocker.