Blood Levels of Calcium, Phosphate Appear to Affect Cognitive Skills
Slower processing speed, or longer times to take in and use information, appear to be connected to lower blood calcium and higher blood phosphate levels in people with hypoparathyroidism, a small pilot study in the U.S. suggests.
Because slower processing speeds can mean more time to complete day-to-day tasks, its researchers noted a perceived poorer quality of life in patients with these altered blood levels. Other affected cognitive domains included episodic memory (recollecting past events and experiences) and working memory (remembering and seeing connections between items or ideas).
“Identification of possible impairment could help with [the] institution of targeted cognitive interventions to reduce symptom burden,” the researchers wrote.
The study, “A pilot study of cognition among hypoparathyroid adults,” was published in the Journal of the Endocrine Society.
Hypoparathyroidism is characterized by a deficiency of parathyroid hormone (PTH), a hormone that helps to control levels of calcium, phosphorus, and vitamin D in the blood. Patients with hypoparathyroidism have hypocalcemia (low blood levels of calcium) and hyperphosphatemia (high blood levels of phosphate, a molecule that contains phosphorus).
Cognitive deficits, often called “brain fog,” and mood changes are commonly reported disease symptoms. For this reason, researchers at Columbia University investigated how cognition and emotion relate to blood levels of calcium and phosphate.
They recruited 19 hypoparathyroidism patients (17 women, two men; mean age of 49) being treated at the university’s Metabolic Bone Disease Unit. Most (95%) developed hypoparathyroidism as the result of a surgery.
The National Institutes of Health Toolbox Adult Cognition Battery (NIHTB-CB) was used to assess cognitive function, the National Institutes of Health Toolbox Emotion Battery (NIHTB-EB) to evaluate emotional health, and the self-reported Short Form Health Survey (SF-36) to measure quality of life.
Of these 19 people, 13 (68%) showed cognitive impairments based on their NIHTB-CB scores. The domain with the lowest scores was processing speed, being particularly low in six patients (32%). More subtle problems were seen in episodic and working memory.
A similar prevalence of cognitive problems was seen across women by age group, the researchers reported. “Global cognition was impaired in 3 of the 4 women aged 20 to 30; in the single woman aged 31 to 40; in 4 of the 5 women aged 41 to 50; and in 5 of the 7 women aged 51 to 60,” they wrote.
Of note, three patients who were on medications affecting cognitive or emotional functioning did not show problems with processing speed.
Emotional well-being, as evaluated via NIHTB-EB scores, was low for nine patients (47%). Most common findings were lesser social satisfaction (eight people; 42%), greater negative affect — a measure of anger, fear, sadness, and stress (six people; 32%), and decreased psychological well-being (four people; 21%).
Compared with the general U.S. population, SF-36 scores were lower among these hypoparathyroidism patients, particularly in areas related to vitality, social functioning, perceptions of general health, and role limitations due to poorer physical health.
Looking at how NIHTB-CB scores related to blood calcium and phosphate, the researchers found that slower processing speed was linked to lower blood calcium and higher blood phosphate levels.
“Slower processing speed (ie, worse performance) correlated with lower corrected serum calcium and lower 24 hour urinary calcium excretion, and higher serum phosphate levels,” they wrote, and this relationship largely remained when comparing the six people with particularly poor processing speed with the other 13 patients. The link between 24-hour urine calcium levels and processing speed, however, did not reach significance.
The association between blood levels of calcium and phosphate and processing speeds also held when researchers repeated their analysis to exclude the three people on medications affecting cognition and emotion.
Poorer perceptions of general health were also linked with “worse cognitive function in the domains of attention, executive function and processing speed,” the study reported, suggesting that these cognitive difficulties affect life quality.
“In conclusion,” the researchers wrote, “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.”
Its findings, they added, “lay the groundwork for further investigation in a larger sample size involving comprehensive neuropsychological evaluation in hypoparathyroid patients and matched controls” that could allow for targeted cognitive treatments “to reduce symptom burden in this rare but debilitating disease.”
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