Expression of Generalized Anxiety Disorder Across the Lifespan.

In generalized anxiety disorder (GAD), both the associated symptoms and worry content have been shown to vary as a function of age (Jeste et al., 2005; Portman et al., 2011). However, few studies have conducted analyses beyond mean comparisons and no studies have examined whether the observed differences in worry content and the associated symptoms are due to the lack of measurement invariance across age groups. The current study evaluated whether the measurement and expression of GAD in adults varied as a function of age, using a clinical sample of 375 participants and dimensional measures of GAD. The sample was divided into three age groups (OLDER = 60+, MID = 40-59, YOUNG = 20-39), matched by sex and GAD status. Two associated symptoms were found to exhibit differential item functioning, overall distress/interference as well as fatigue, with higher levels distress/interference and lower levels of fatigue found in the OLDER age group despite equivalent GAD severity levels across groups. When examining the content of reported worries, differential item functioning was found in four worry domains. Holding the latent dimension of worry severity constant: (a) the YOUNG age group was found to have higher reported rate of social worries, and (b) the OLDER age group was found to have higher levels of reported worries about community/world affairs and health of self. The OLDER age group also exhibited lower levels of worry about work and school. These results are discussed with regard to the assessment of GAD across the lifespan.