Cognitive dysfunction and regional cerebral blood flow changes in Japanese females after human papillomavirus vaccination

Background Human papillomavirus vaccination is used to prevent cervical cancer in adolescent females; however, few vaccinated individuals show long-lasting symptoms. Aim We investigated cognitive dysfunction and regional cerebral blood flow changes in human papillomavirus-vaccinated patients to estimate their pathological condition. Methods We retrospectively included patients with cognitive dysfunction after human papillomavirus vaccination. N-isopropyl-(123I)-p-iodoamphetamine single-photon emission computed tomography images of patients were compared with those of 10 healthy unvaccinated females (19.6 ± 0.5 years) using 3-D stereotactic surface projection and stereotactic extraction estimation methods. We also investigated the correlation between the Wechsler Adult Intelligence Scale-Third edition score and anatomical region with decreased regional cerebral blood flow. Results A total of 17 females (age 17.7 ± 1.4 years) showed cognitive dysfunction, including memory impairment (17 patients, 100%), acalculia (4, 23.5%), transient prosopagnosia-like symptoms (3, 17.6%), and topographical impairment and hemispatial neglect (2, 11.8%). Significantly decreased regional cerebral blood flow was found in the right medial frontal, subcallosal, anterior cingulate, orbital, rectal, parahippocampal, fusiform gyrus, left angular and superior occipital gyrus, and bilateral thalamus. Significant negative correlations were found between the full scale intelligence quotient and extent of decreased regional cerebral blood flow in the right medial frontal and rectal gyrus, verbal intelligence quotient and right subcallosal, rectal gyrus and left thalamus, and performance intelligence quotient and the right medial frontal gyrus. Conclusion In patients with cognitive dysfunction after human papillomavirus vaccination, regional cerebral blood flow was decreased mainly in the regions connected to the limbic system. Hypoperfusion in the limbic system might reflect cognitive dysfunction, mainly memory impairment, after human papillomavirus vaccination.