Olfactory hallucinations in schizophrenia and schizoaffective disorder: A phenomenological survey

Prevalence and phenomenology of olfactory hallucinations in Parkinson's disease: Table 1

“…The clinical characteristics of OHs in PD are close to those observed following upper respiratory infection and head trauma, with mainly unpleasant odours, awareness of the unreal nature of the hallucination and little impact on the quality of life. OHs are also described in schizophrenic patients for whom they are often more complex, with only partial insight 8. In partial epilepsy, OHs are associated with localised hypersynchronous neuronal discharges in a cortical area.…”

A preliminary investigation of olfactory function in olfactory and auditory-verbal hallucinators with schizophrenia, and normal controls

“…Unfortunately, we did not ask participants further details about the particular incident (or incidents) as we had no a priori expectation of this observation and were simply intending to confirm absence of likely major brain injury due to accident and/or assault. We did, however, ask all of our 51 OH participants (Stevenson et al, 2011) who completed an earlier survey whether they had ever had any head injury (noting the difference in the question). In that study (Stevenson et al, 2011), 33.3% reported a prior head injury (again no further questions were asked about this), and that proportion did not significantly differ from the proportion observed in the current study (50.0%; noting that these samples are not completely independent).…”

“…We did, however, ask all of our 51 OH participants (Stevenson et al, 2011) who completed an earlier survey whether they had ever had any head injury (noting the difference in the question). In that study (Stevenson et al, 2011), 33.3% reported a prior head injury (again no further questions were asked about this), and that proportion did not significantly differ from the proportion observed in the current study (50.0%; noting that these samples are not completely independent). This may suggest that frequency of this type of injury may be higher in people with OH and schizophrenia.…”

“…Nine of the OH participants had previously taken part in an in-depth structured interview concerning the phenomenology of their olfactory hallucinations (Stevenson et al, 2011). In addition, 20 of the participants here with schizophrenia had taken part in a related neuropsychological study within the previous month.…”

“…Within individuals who report OHs, the rate at which they occur can vary widely. Stevenson, Langdon, and McGuire (2011), interviewed 51 individuals with schizophrenia who reported having experienced OHs. This study revealed considerable variation in the weekly frequency of OHs, from less than 1/week to 28/week (mean04.4).…”