S99. DRUG ABUSE AFFECTS THE RISK OF STRESSFUL HALLUCINATIONS IN THE GENERAL DUTCH POPULATION

BACKGROUND: Auditory (AH) and visual (VH) hallucinations can be very stressful for patients with psychotic disorders. These hallucinations also occur in healthy individuals, but mostly without the accompanying stress seen in patients. This study assesses AH and VH in a general population and examines whether or not hallucinations are stressful. The aim of the current investigation is to identify factors that predict the presence or absence of hallucinatory distress. This information is of importance to understand the transition of transient and harmless hallucinations towards distressing ones, which is a crucial step in the development of psychosis. We examined the effect of drug usage on the risks of experiencing distress from AH and VH across the Dutch population (≥ 14 years of age) by means of an online survey. METHODS: Participants filled out the Questionnaire for Psychotic Experiences and a questionnaire about drug usage during the past week and month. Only participants who reported having experienced AH and/or VH during the past week or month were included in the analysis. Participants were divided into 3 age-groups (young: aged 14 – 22; middle-aged: aged 23 – 30; older: aged 31 – 100) to control for the effect of age. Prevalence rates were calculated and binary logistic regression was used to analyze odds ratios (ORs) (with gender and level of education as covariates). RESULTS: The total sample consisted of 3897 participants. The usage of cannabis during the past week or month increased the risk of experiencing more frequently AHs for older individuals (OR = 2.00) and the usage of the psychoactive drug 4-Fluoramphetamin (4-FA) decreased the risk of experiencing more frequently VHs for middle-aged individuals (OR = 0.24). Moreover, older individuals had a decreased risk of experiencing distressing AHs if they consumed alcohol (OR = 0.52) and a decreased risk of experiencing distressing VHs if they consumed at least one drug during the past week or month (OR = 0.59), without any one drug in particular driving this effect. Interestingly, the usage of alcohol deceased the risk of experiencing distressing AH for individuals who frequently experience AHs (OR = 0.71) as well as for individuals who seldom experience VHs (OR = 0.52). Strikingly, for individuals who frequently experience VHs the usage of nitrous oxide (N2O), a drug rapidly gaining popularity among adolescents, increased the risks of experiencing distressing VH threefold (OR = 3.58). DISCUSSION: The current study suggests a crucial role of drug use on the risks of experiencing frequent and distressing AH and VH in middle-aged and older individuals. Whereas the increased risk of experiencing more frequently AHs for individuals who used cannabis support previous findings, the decreased risk of experiencing frequently VHs for participants who used the psychoactive substance 4-FA is more puzzling. Our data further highlights the possibility that individuals who more frequently experience AH as well as those who do seldom experience VH may use alcohol as self-medication. Results propose that recent usage of N2O imposed a threefold increased risk of experiencing distressing VH. As N2O is becoming an increasingly popular recreational drug, but as of yet little is known about its possible negative impact on VH, these results should be taken as incentive for further studies. In conclusion, the current results suggest that drug use are associated with frequency of and level of distress caused by hallucinations in the general population. As such, these factors could be important targets for early interventions aimed at individuals who are not, but may be at risk of becoming, part of a clinical population.