Insular impairments in chronic physical diseases and implications for
symptom perception: a systematic review.
Abstract
This study aimed to explore whether patterns of insular impairment exist
among adults with chronic physical diseases. Considering the relevance
of interoception in the symptom experience, we also paid attention to
analyses of the relationship between the insula and disease-related
symptoms. In this systematic review we included primary research (all
designs) assessing the structure and/or activity of the insula through
(f)MRI in adults with chronic physical diseases (vs healthy-controls).
We reported results as a narrative synthesis. We included fifty studies
investigating the structure or activity of the insula in diabetes,
cancer, heart failure, chronic pulmonary disease. Nineteen studies
explored insular structure and found patients with chronic diseases
having lower/damaged insular volume/density/thickness than healthy
controls, or reduced insular blood flow. Twenty-two studies explored
insular activity and the majority reported higher insular activity and
lower connectivity in patients. Five studies explored the association
between insular volume/activity and symptom severity: four reported a
positive trend, one reported a negative association. In conclusion,
people with chronic physical diseases have lower insular grey matter
volume/density/thickness and abnormal insular activity (i.e., higher or
lower) than healthy subjects. There seems to be a positive trend between
insular activity and symptom severity. These results a) can better
explain impaired interoceptive abilities in chronic physical diseases,
b) shed light on the relevance to implement interventions addressing
insular activity to improve interoceptive functioning and ultimately
enhance body awareness and symptom management in patients with chronic
diseases.