For the very paranoid everyone is a threat

Previous research has shown that even neutral social contact can trigger paranoid thinking in people with paranoia. Social contact can have a wide variety of different contexts from complete strangers to friends and family and a team of researchers led by Dina Collip from Maastricht University studied 154 people assessing their paranoia and asking them to record their feelings in everyday life. People with low and medium levels of paranoia reported higher levels of perceived social threat when they were with less familiar people, however, people with high levels of paranoia showed no difference in the level of perceived threat between familiar and unfamiliar people.

Collip, D. ... [et al] - Social world interactions: how company connects to paranoia Psychological Medicine (2011), 41: 911-921