Structural and Functional Neuroimaging Findings in Delusional Disorder: Diagnostic and Therapeutic Implications

Background: Although structural and functional abnormalities have been found in patients with schizophrenia, very few studies have investigated neuroimaging features in delusional disorder patients. We conducted a review of the literature to assess the evidence for specific neuroimaging changes in delusional disorder on brain structures and functions. Method: We reviewed the literature on structural and functional neuroimaging studies of delusional disorder between 1980 and April 2014. The search was conducted through MEDLINE, Pubmed and Web of Knowledge, using the following key words: delusional disorder, neuroimaging, brain imaging, magnetic resonance, MRI, computerized tomography, TC, single photon emission tomography, SPECT, functional magnetic resonance, fMRI, positron emission tomography, PET and spectroscopy. Results: According to our inclusion criteria, 15 studies were included in the review. 14 studies reported structural brain data, and 10 studies reported functional findings. Due to the heterogeneity of the neuroimaging techniques, a meta- analysis could not be conducted. The vast majority of structural neuroimaging studies found brain atrophy and white matter lesions in DD patients, particularly in the temporoparietal or frontal lobes. Functional neuroimaging studies pointed to the temporal and parietal lobes, as well as the basal ganglia, as potential brain areas implicated in the clinical manifestation of DD, particularly in those patients affected with the somatic type, and as potential neuroimaging markers of clinical response in these populations. Conclusion: Temporo-parietal, prefrontal, and basal ganglia dysfunction, as well as dysfunctions in other specific brain regions, may be implicated in the core symptoms of delusional patients. More complex functional brain network analyses and multivariate statistics would provide higher evidence in future research.