Descriptive Psychopathology: The Signs and Symptoms of ...

80 Section 1: Present, past, and futurein patients with migraine, epilepsy, temporal lobe hemorrhage, and brain tumors.Olfactory hallucinations are also seen in patients with schizophrenia, depressiveillness, and eating disorder. 156Delusions 157 There are no systematic studies assessing brain structural and functional neuroimagingin persons with delusions, and the meager findings are inconsistent.There is no synthesis across methods and technologies used, the diagnoses of thepatients studied, and important clinical features such as chronicity. Many studiesdo not differentiate between delusions and hallucinations, and lump themtogether as “psychotic features”. 158 The only consistent finding is that delusionalpatients have disturbances in frontal–temporal–limbic networks. 159 This is neurologicallyconsistent with the delineated phases of delusions (see Chapter 11), butnon-specific as many forms of psychopathology are associated with dysfunctionin these brain regions.Many studies focus on delusions in patients with seizure disorder, schizophreniaor Alzheimer’s disease, confounding interpretation of findings are the results,the reflection of the disease process or the processes leading to the delusion. Forexample, Kimhy et al. (2005) construct a psychological theory of delusions basedon cerebral blood flow studies that report that patients with grandiose delusionsassociated with excitement have increased cerebral blood flow 160 while patientswith persecutory delusions have decreased cerebral blood flow 161 during tasks ofself-assessment and self-relevance. The likelihood, however, is that the findingsreflect differences between mania and schizophrenia, not the different content ofthe delusions.Cerebral blood flow studies in patients with schizophrenia also commonly findabnormalities in the left prefrontal and temporal lobe cortex and in the leftstriatum, and are interpreted to represent the underlying process of persecutorydelusions. 162 However, schizophrenic patients are identified by their abnormalspeech and language and avolition, clinical features associated with left-sidedfrontal–temporal brain dysfunction. Thus, the cerebral blood flow findings likelyreflect schizophrenia, not a unique pathophysiology for delusions. Similarly, in aseries of studies examining the regional cerebral blood flow of patients withpsychotic depression, the investigators delineated abnormalities they associatedwith illness severity and delusions, but the findings are also typically seen innon-psychotic patients with melancholia. 163Among studies of patients with schizophrenia, some examine first-episodepatients while others focus on the chronically ill, making synthesis difficult.Further, the delusions studied are almost never defined by their form, soany pathophysiologic differences between primary or secondary delusions, for