Does hypothyroidism increase the risk of cognitive impairment and dementia in elderly?

Does hypothyroidism increase the risk of cognitive impairment and dementia in the elderly? If you’ve ever asked yourself that question you are among the many others who ponder it as well.

Roughly, four to 15 percent of Americans have subclinical hypothyroidism – underactive thyroid. Along with the usual symptoms of fatigue and weight gain, a study has found that a subclinical hypothyroidism diagnosis in those younger than the age of 75 puts them at risk for cognitive impairment and dementia.

The Italian researchers looked at 13 studies that explored the effects of subclinical hypothyroidism on the brain. The researchers found that 56 percent of patients had an increased risk of cognitive function impairment and 81 percent had an increased risk of dementia.

Professor at Harvard School of Medicine James Hennessey said, “Mild, non-specific neuro-cognitive symptoms may be seen in subclinical hypothyroidism. Individuals with such symptoms deserve to have their thyroid function tested — and if they are clearly subclinical hypothyroid, levothyroxine therapy should be considered.”

“It turns out that our TSH levels tend to drift up with age, such that by the time we’re over 80, the upper limit of the TSH has been observed to be over six to seven. In these studies, people were considered to have subclinical hypothyroidism if their TSH levels were greater than four to five,” Dr. Hennessey explained.

He continued, “Diluting the sample with ‘normal’ people made it difficult to demonstrate that subclinical hypothyroidism had an adverse impact on cognition. The younger we are, the more likely it is that subclinical hypothyroidism will have an impact on cognition, as shown in this meta-analysis.”

Signs of subclinical hypothyroidism are often so subtle that most patients brush them off or believe these are signs of aging as opposed to a more serious underlying condition.

There are currently no guidelines for TSH screening, so if you start spotting the signs – dry skin, paleness, puffy face, constipation, hoarse voice, weight gain – you may want to have your levels checked by a doctor.

Hypothyroidism and its association with mild cognitive impairment in elderly

Whether your thyroid is overactive or underactive, either one can have implications on your health, including impact on the brain health. Hypothyroidism is associated with mild cognitive impairment in the elderly, and running thyroid tests is fairly common when individuals report memory problems.

In one study, researchers analyzed face-to-face interviews along with neurological and psychological tests. Patients were classified by thyroid function including euthyroid (with normally functioning thyroid), clinically hypothyroid, or having subclinical hypothyroidism. There were a total of 1,904 patients involved.

Of those involved, 316 were found to have mild cognitive impairment. Mild cognitive impairment was found in 16.3 percent of euthyroid participants, 17.2 percent of clinically hypothyroid patients, and 17.7 percent of those with subclinical hypothyroidism. Normal factors that could play a role in mild cognitive impairments were age, education, and other medical conditions, but they were not found to have an impact on mild cognitive impairment as much as hypothyroidism did.

The researchers suggest performing additional studies as the results came up mixed.

Hypothyroidism and its association with mild cognitive impairment in elderly

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