Reframing delusional infestation: perspectives on unresolved puzzles

Delusional infestation (DI), a debilitating psychocutaneous condition, featured as a false fixed belief of being infested accompanied by somatosensory abnormality, behavior alteration, and cognitive impairment. Although management of primary causes and pharmacotherapy with antipsychotics and/or antidepressants can help to alleviate symptoms in most patients, the underlying etiology of DI still remains unclear. Morgellons disease (MD), characterized by the presence of cutaneous filaments projected from or embedded in skin, is also a polemic issue because of its relationship with spirochetal infection. This review aims to discuss the following topics that currently confuse our understandings of DI: 1) the relationship of real/sham “infestation” with DI/MD; 2) behavior alterations, such as self-inflicted trauma; 3) neuroimaging abnormality and disturbance in neurotransmitter systems; and 4) impaired insight in patients with this disease. In discussion, we try to propose a multifactorial approach to the final diagnosis of DI/MD. Future studies exploring the neurobiological etiology of DI/MD are warranted.