napadow

Vitaly Napadow
Associate Professor, Martinos Center for Biomedical Imaging, Massachusetts General Hospital & Associate professor and Director of the Center for Integrative Pain Neuroimaging, Harvard Medical School

When perception is reality: How nocebos mimic real pruritogens in brain processing of itch

Psychological factors are known to significantly modulate itch in patients suffering from chronic itch. Itch is also highly susceptible to both placebo and nocebo (negative placebo) effects. Moreover, brain activity likely supports nocebo-induced itch, but is currently unknown. We collected functional MRI (fMRI) data from atopic dermatitis (AD) patients, in a within-subject design, and contrast brain response to nocebo saline understood to be allergen vs open-label saline control. Analyses also compared results to real allergen itch response and placebo responsiveness, evaluated in the same patients. Nocebo saline produced greater itch than open saline control and compared to open saline, nocebo saline demonstrated greater fMRI response in caudate, dorsolateral prefrontal cortex (dlPFC), and intraparietal sulcus (iPS) – brain regions important for cognitive executive and motivational processing. Furthermore, we found that subjects with greater dlPFC and caudate activation to nocebo-induced itch also demonstrated greater dlPFC and caudate activation, respectively, for real allergen itch. Subjects reporting greater nocebo-induced itch also demonstrated greater placebo reduction of allergen-evoked itch, suggesting increased generalized modulation of itch perception. Our study demonstrates the capacity of nocebo saline to mimic both the sensory and neural effects of real allergens and provides an insight to the brain mechanisms supporting nocebo-induced itch in AD, thus aiding our understanding of the role that expectations and other psychological factors play in modulating itch perception in chronic itch patients. Our results show that our brains have an amazing capacity to recreate the world around them, even without the afferent stimulus we think is necessary to produce certain sensations.

Biosketch

Vitaly Napadow is an Associate Professor at the Martinos Center for Biomedical Imaging at Massachusetts General Hospital and Harvard Medical School in Boston, MA, where he is also the Director of the Center for Integrative Pain Neuroimaging (CiPNI). He received his Ph.D. in biomedical engineering from the Harvard-MIT Health Sciences and Technology program and Dr. Napadow’s laboratory has pioneered the application of non-invasive neuroimaging techniques to better understand the brain circuitry underlying aversive perceptual states, such as pain, itch, and nausea, and to better understand how neuromodulatory mind-body therapies such as acupuncture and placebo interventions ameliorate these states. Dr. Napadow has more than 100 publications in leading peer-reviewed journals, and serves on review panels for the National Institutes of Health and leading journals in the field.