Is there a relationship between loneliness and psychotic experiences? An empirical investigation and a meta-analysis
Michalska da Rocha, Beata
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Purpose The aim of the systematic review and meta-analysis was to determine the magnitude and strength of the loneliness-psychosis relationship, and to synthesise current evidence. The aim of the empirical investigation was to establish whether, in older people, loneliness may increase proneness to auditory hallucinations and perceiving visual human-like features in ambiguous stimuli. Methods For the meta-analysis a search of electronic databases was conducted (PsychINFO, MEDLINE, EMBASE and Web of Science). Studies were included if they reported usable data relating to the association between loneliness and psychotic symptoms. A random effects meta-analysis was used to compute a pooled estimate of the correlation, together with 95% Confidence Intervals (CI). Study quality and outcome quality were systematically assessed using adapted versions of the Agency for Healthcare Research and Quality (AHRQ) tool and GRADE approach, respectively. For the empirical study, a parallel group experimental design with random allocation to experimental conditions was employed. Participants (62 healthy adults aged 65 and above) were assigned to one of the two conditions – the experimental condition or a control condition. A loneliness induction procedure was employed in the experimental condition whereas participants in the control condition completed a neutral task. A logistic regression was conducted to evaluate performance on auditory and visual tasks across the groups and an odds ratio was calculated. Results Thirteen studies were included in the meta-analysis, providing data from 15,647 participants. A moderate association between psychosis and loneliness was observed (k=13, N=15,647, r=0.32, 95% CI 0.20, 0.44; I2 97.56%; moderate quality evidence). Whether loneliness was assessed by single-item or a more comprehensive measure had no moderating effect on the estimate. The experimental study revealed that participants in the neutral condition were significantly less likely to hear words in ambiguous stimuli than those in the experimental condition (OR = 0.70, 95% CI 0.51 – 0.94, p < 0.05). Exploratory analysis revealed that higher scores on the state loneliness measure were associated with an increase in the likelihood of hearing words (OR=1.17, 95% CI 1.01-1.35, p = 0.03). No effect of loneliness induction was found on perceiving human-like features in ambiguous visual stimuli. Conclusions The meta-analysis confirmed a significant positive relationship between loneliness and psychosis, while the experimental study suggested that loneliness may have a causal role in the development of subclinical auditory experiences in older people. Further studies examining whether loneliness is involved in proneness to other psychotic experiences would be beneficial.