Hallucinations may occur in different sensory modalities (e.g., auditory, visual, olfactory, tactile, and gustatory).
Auditory hypnagogic hallucinations full#
The occurrence of nonclinical hallucinations represents a risk factor for conversion to full psychosis (e.g., Kelleher and Cannon, 2011), even though it is not necessarily followed by a psychotic diagnosis ( Verdoux et al., 1999 Johns and van Os, 2001). Indeed, the onset of psychosis is often preceded by an increased frequency of nonclinical psychotic symptoms (e.g., Hanssen et al., 2005 Larøi and van der Linden, 2005a Dominguez et al., 2011 Larøi, 2012) in co-occurrence with clinical conditions conditions such as anxiety, depressed mood, suspiciousness, disorganization, irritability, social withdrawal, poor functioning, and cognitive and behavioral changes (e.g., Yung and McGorry, 1996 Yung et al., 2003). Differences between clinical and nonclinical psychotic symptoms seem to be quantitative rather than qualitative (e.g., Larøi and van der Linden, 2005a Larøi, 2012). Of note, nonclinical cases represent the largest proportion of the full continuum ( van Os et al., 2009). Three distinct states are thought to represent the phenotypic continuum of psychosis: (1) brief and attenuated psychotic experiences in the healthy population (typically hallucinations and delusions) observed in the least severe extreme (2) persistent sub-clinical psychotic symptoms without functional impairment occurring from the least severe to the most severe extreme and (3) psychotic disorders with symptoms that cause clinically significant distress and functional impairment occurring in the most severe extreme ( van Os et al., 2009). These findings provided support for a continuum model of psychotic experiences that extends not only across diagnostic categories, but also into the (non-clinical) general population (e.g., Johns and van Os, 2001 Bradbury et al., 2009 Brébion et al., 2010). Even though the experience of hallucinations is considered a hallmark of psychotic disorders (e.g., David, 1994 Johns et al., 2004), hallucinations may also be present in 10–15% of individuals with no clinical diagnosis (e.g., Barrett and Etheridge, 1992 Paulik et al., 2006 Badcock et al., 2008 Sommer et al., 2010). Hallucinatory experiences, usually defined as perceptual experiences that occur in the absence of corresponding external sensory stimulation ( Slade and Bentall, 1988), are a clinical manifestation of psychiatric disorders such as schizophrenia ( Mueser et al., 1990 Baethge et al., 2005). Hallucinations represent one of the most intriguing phenomena (e.g., Allen et al., 2008), and have been in the spotlight of researchers from many disciplines for decades. Specifically, increased schizotypal tendencies and negative mood (anxiety and depression) may be related to increased psychotic risk. Further, they support an association between clinical symptoms and increased vulnerability to hallucinations. These results corroborate the lower severity of hallucinations in the general population compared to psychotic individuals. In addition, hallucination predisposition was associated with increased clinical symptoms. However, the more pleasant they were perceived, the more controllable they were assessed. Although, fundamentally perceived as positive experiences, all types of hallucinations were described as uncontrollable and dominating. Intrusive or vivid thoughts and sleep-related hallucinations were the most common. A three-factor solution for the LSHS Portuguese version proved to be the most adequate. Of those, 16 participants with high LSHS scores and 14 with low LSHS scores were further screened for clinical symptoms. Three-hundred-and-fifty-four European Portuguese college students completed the LSHS.
This study aimed to examine the psychometrics proprieties of the Portuguese adaptation of the 16-item Launay-Slade Hallucinations Scale (LSHS), the phenomenological characteristics of nonclinical hallucinatory experiences in a Portuguese sample, and the relationship between clinical symptoms and hallucination predisposition. Despite the increased number of studies probing the incidence of nonclinical hallucinations, the underlying phenomenological characteristics are still poorly understood. The experience of hallucinations is a hallmark of psychotic disorders, but they are also present in other psychiatric and medical conditions, and may be reported in nonclinical individuals. 2Faculty of Psychology, University of Lisbon, Lisbon, Portugal.1Neuropsychophysiology Lab, CIPsi, School of Psychology, University of Minho, Braga, Portugal.
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