Examining familial risk factors for social anxiety disorder: Intolerance of uncertainty and related personality traits.

Intolerance of uncertainty (IU) is an individual difference dimension reflecting difficulty in tolerating aversive responses triggered by uncertainty. IU is an important etiological and maintaining mechanism of social anxiety disorder (SAD). However, IU's role as a familial risk factor for SAD remains unresolved. In the present study, we sought to 1) confirm that SAD runs in families (as per prior studies), 2) test if IU also runs in families, and 3) examine if IU is a familial risk factor for SAD. We also explored other related personality factors that could also be familial risk factors for SAD. Analyses were conducted in a family study of psychopathology (n = 725 siblings and parents in 246 families). SAD severity was assessed with the Inventory of Depression and Anxiety Symptoms (IDAS-II) social anxiety scale. IU was assessed with the Intolerance of Uncertainty Scale, short form (IUS-12). SAD and IU both demonstrated familial aggregation (intra-class correlation coefficients of 0.10 and 0.14, respectively). However, families' average IU scores did not predict individual's SAD history after accounting for the individual's IU. Results were similar for neuroticism, anxiousness, and detachment. In contrast, when familial analyses were restricted to exploratory intergenerational analyses only, parental SAD predicted offspring's IU but offspring IU did not predict personal SAD. These findings suggest that although IU is a known risk factor for SAD, and both IU and SAD appear to transmit in families, IU may not be a familial risk factor for SAD, although parental SAD may be a risk factor for elevated levels of offspring IU. Other risk factors, besides shared familial factors between IU and SAD, may better explain how SAD is transmitted through families.