[Conspiracy theories, social polarization and crises].

Objective: Social media facilitate the distribution of conspiracy theories. It is uncertain whether indeed the number of myths and also the number of those who appropriate myths has increased. Conspiracy theories have so far essentially been the subject of sociological and psychosociological research showing a general disposition to become infected irrespective of the topic of a myth. Are there specific psychopathological risk factors for becoming infected by conspiracy myths? Are there effective therapeutic or preventive measures?

Methods: A systematic search was carried out in PubMed using the query "conspir*[title] AND review" followed by manual selection and appraisal only of publications addressing conspiracy theories in general, i.e. not limited to specific myths, with a focus on systematic reviews and meta-analyses. Moreover, the publications identified were manually screened for further meta-analyses.

Results: The search resulted in 166 hits. The available evidence is essentially based on studies using questionnaires, which can clarify only associations but not causalities. The evidence suggests that the strongest correlates of conspiratorial ideation pertain to low cognitive abilities, nonanalytic style of thought resulting in reduced balancing of probabilities before deciding, feelings of loss of control, paranoia, schizotypy and the dark triad (narcissism, Machiavellianism, authoritarianism).

Conclusion: Specific psychological characteristics are risk factors for conspiratorial ideation. Current research approaches are unsuitable to clarify whether psychiatric disorders are overrepresented. Sociodemographic risk factors include male gender, low level of education, low income, social isolation and are non-specific. Group processes promote, again presumably nonspecifically, conspiracy theories thus contributing to social polarization. The genetic basis and neurobiological mechanisms are unknown. Conspiracy theories were and are used as an instrument of political contention. The enlightened democratic social contract requires free, unbiased thinking. Consequently, the risk factors identified so far facilitate conspiratorial ideation and question the very fundaments of the social contract by impairing unbiased evaluation and decision making. Therefore, prevention is warranted. .