Results of a small pilot study showed that impaired cognition was common in adults with hypothyroidism and linked to lower serum calcium levels and higher serum phosphate levels.

Despite patients with hypoparathyroidism describing cognitive deficits, data are limited regarding objective assessment of cognitive function, Mishaela R. Rubin, MD, MS, an associate professor of medicine in the metabolic bone disease unit at the Vagelos College of Physicians & Surgeons at Columbia University Irving Medical Center, and colleagues wrote. The researchers sought to determine objective cognition in adults with hypoparathyroidism using the NIH Toolbox Cognitive Battery (NIHTB-CB) and aimed to assess whether cognition is linked to emotion, quality of life and hypoparathyroidism-related biochemistries.

The researchers defined impairment as fully demographically adjusted T-score less than 1.5 standard deviation in at least one cognitive domain or less than 1 standard deviation in two or more domains.

The study included 19 participants (median age, 49 years; 84% white) with hypoparathyroidism, of whom 17 were women and 18 had postsurgical hypoparathyroidism. All participants had at least a high school degree, while most worked in professional settings and three were on medications known to affect cognitive function or emotion.

Researchers reported impaired demographically adjusted NIHTB-CB cognition scores for 13 participants and noted that cognition scores were connected to self-reported perception of general health.

Processing speed was the most commonly impaired cognitive domain, with T-scores that were below or equal to 2 standard deviations among 32% of participants. Moreover, processing speed corresponded with serum calcium levels (P = .023) and inversely with serum phosphate levels (P = .042).

“This small pilot study suggests that impaired cognition might be present in hypoparathyroid subjects and may be associated with lower serum calcium and higher serum phosphate levels,” Rubin and colleagues concluded. “These preliminary data are hypothesis-generating and lay the groundwork for further investigation in a larger sample size involving comprehensive neuropsychological evaluation in hypoparathyroid patients and matched controls.”

The researchers further noted that a future direction is to assess whether duration of hypocalcemia and/or hyperphosphatemia correlate with more impaired cognitive function. “Identification of possible impairment could help with institution of targeted cognitive interventions to reduce symptom burden in this rare but debilitating disease,” they wrote.