Research report Is behavioral inhibition a risk factor for depression? Gemma L. Gladstone ⁎ , Gordon B. Parker School of Psychiatry, University of New South Wales and Mood Disorders Unit, Black Dog Institute, Prince of Wales Hospital, Randwick, New South Wales, 2031, Australia Received 13 October 2005; received in revised form 13 April 2006; accepted 18 April 2006 Available online 30 June 2006 Abstract Background: Several studies have reported an observed relationship between a behaviorally inhibited temperament early in life and subsequent clinical anxiety, but few have explored the relationship between early inhibition and depression. Methods: In a cross-sectional survey of non-clinical adults we examined the relationship between retrospectively reported childhood behavioral inhibition and lifetime depression. We then examined the mediating role of social anxiety and childhood relational stress factors. Results: Subjects who qualified for a lifetime episode of depression also reported significantly more childhood inhibition, particularly if they had a juvenile onset depression (i.e., by age 16). Further analyses revealed that social anxiety mediated the link between reported childhood inhibition and later depression, and highlighted the additional meditating effect of parental influences. Conclusion: Any relationship between an early inhibited temperament and later depression, may in fact be dependent upon the presence of clinically meaningful social anxiety. © 2006 Elsevier B.V. All rights reserved. Keywords: Depression; Behavioural inhibition; Social anxiety; Temperament 1. Introduction Behavioral inhibition is a construct of temperament originally studied in young children by Kagan and colleagues (Garcia-Coll et al., 1984) and refers to a behavioral style which is typically restrained, wary and fearful in response to novel and unfamiliar social and non-social stimuli. This temperament construct has attracted research attention as a possible precursor to clinical anxiety (Hirshfeld-Becker et al., 2003), with some research demonstrating specific links with social anxiety disorder (Biederman et al., 2001; Gladstone et al., 2005; Hayward et al., 1998; Schwartz et al., 1999; Muris et al., 1999, 2001). There is also evidence that behavioral inhibition may constitute a developmental risk for unipolar depression (Caspi et al., 1996; Muris et al., 1999, 2001; Reznick et al., 1986; Rubin and Mills, 1991). Jaffee et al. (2002) for example, followed a birth cohort prospectively assessed over 26 years, and found that originally inhibited children were more likely to develop depression, particularly juvenile onset depression (i.e., by 16 years). Co-morbidity of depression and anxiety disorders is common and the co-occurrence of depressive and anxiety symptoms is high (Lydiard, 1998; Malhi et al., 2002). Individuals with anxiety disorders are at greater risk for developing depression (Cole et al., 1998; Stein et al., 2001; Wittchen et al., 2000), and the presence of Journal of Affective Disorders 95 (2006) 85 – 94 www.elsevier.com/locate/jad ⁎ Corresponding author. Fax: +61 2 9382 3712. E-mail address: psychdirect@aol.com (G.L. Gladstone). 0165-0327/$ - see front matter © 2006 Elsevier B.V. All rights reserved. doi:10.1016/j.jad.2006.04.015