Altered Brain Functioning May Explain Cognitive Difficulties and Depression After Thyroid Hormone Withdrawal Following Thyroidectomy
Commentary by lead author Won Bae Kim, MD; co-author Jin Pyo Hong, MD; and, Joanne Rovet, PhD
Patients with acute hypothyroidism following total thyroidectomy have increased local brain functional connectivity, which correlates with poorer mental quality of life and depression, according to a study in the May issue of Thyroid.
“The findings confirm the concerns that thyroid withdrawal has an acute influence on brain function, which mediates negative psychological effects of thyroid hormone withdrawal in patients with total thyroidectomy,” said senior author Won Bae Kim, MD, Department of Internal Medicine, Asan Medical Center, University of Ulsan College of Medicine, Seoul, South Korea.
“The complaint of psychological distress from the patients during the total hormone withdrawal period has a solid pathophysiological background in the brain,” said study coauthor Jin Pyo Hong, MD, Department of Psychiatry, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, South Korea.
Study Involved 21 Patients
The study involved 21 patients who underwent total thyroidectomy because of thyroid cancer. Before and two weeks after thyroid hormone withdrawal (THW), the patients were assessed using resting state fMRI of the brain and thyroid function tests, and they completed both the 12-Item Short Form Health Survey (SF-12) and the Patient Health Questionnaire-9 (PHQ-9). Regional homogeneity (ReHo) used as a measure of functional connectivity was evaluated in 19 of the patients before and after THW.
THW was linked to increased ReHo in primary motor and sensory, visual, and association cortices. ReHo values in specific areas (ie, bilateral pre- and postcentral gyri, bilateral middle occipitotemporal cortices, the left precuneus, and the left lingual gyrus) were positively correlated with serum thyrotropin levels after THW. Higher ReHo values in some of these same areas (ie, bilateral pre- and postcentral gyri, the left middle temporooccipital cortices, and the left ligual gyrus) correlated with the lower mental component summary score on the SF-12. In contrast, higher ReHo values in the bilateral pre- and postcentral gyri correlated with higher total scores in the PHQ-9, indicating more severe levels of depression.
It is unclear why there was increased activity in these diverse brain regions in patients with THW, commented Joanne Rovet, PhD, who is a Senior Scientist in the Neuroscience and Mental Health Program at The Hospital for Sick Children in Toronto, and Professor of Pediatrics and Psychology at the University of Toronto. “It may be that increased brain effort is needed to process information,” she said.
How Endocrinologists Help Patients With Cognitive Difficulties After Thyroidectomy
“Physicians can explain to patients that the withdrawal effect of thyroid hormone is acute but transient,” Dr. Kim said. “Using recombinant human thyroid-stimulating hormone could be an option to bypass the unnecessary side effect of thyroid hormone withdrawal in treating the patients,” Dr. Kim added.
“Endocrinologists need to be closely linked to local mental health resources to refer patients to who suffer from cognitive difficulties or mood disorders following thyroidectomy,” Dr. Rovet said.
“In my experience, some endocrinologists may minimize psychological complaints and a slight IQ loss, just as long as patients appear to be functioning normally,” Dr. Rovet continued. Thus, increased awareness of the impact of these deficits on patient’s quality of life is important, she said.
Dr. Rovet has conducted studies of cognitive development in children with congenital hypothyroidism or who are the offspring of women with hypothyroidism during pregnancy and found cognitive impairments in memory and attention and in visual processing. While she found slightly different levels of impairment depending on whether children had congenital hypothyroidism or were exposed to hypothyroidism in utero, in both cases, structural and functional effects were found in the cortex, including the hippocampus, and these were linked to the cognitive problems and to the severity of either the child’s or the mother’s hypothyroidism, Dr. Rovet explained.
In addition, Dr. Rovet suggested that future studies of patients with thyroid cancer need to investigate other psychological endpoints, such as learning and memory. Further, research is also needed to determine if these alterations are transient or permanent, or something in between, she said.
June 7, 2016