Prevalence and Co-Occurrence of Internalizing and Externalizing Depression Symptoms in a Community Sample of Australian Male Truck Drivers

Trucking industry employees are known to be at risk of elevated levels of stress and a range of behaviors that may compromise their mental health. Clinical reports indicate that in response to negative emotional states, men tend to engage in a cluster of externalizing behaviors including irritability, anger and aggression, risk taking, and substance misuse. However, as such symptoms fall outside standard diagnostic depression criteria, the diagnosis and treatment of depression in men may be impeded. The present exploratory study reports retrospective symptom ratings of internalizing and externalizing depression symptoms from 91 Australian male truck drivers. Moderate correlation between externalizing and internalizing symptoms was reported across the sample, though internalizing symptoms were reported more frequently. However, consistent with prediction, those meeting probable depression caseness (n = 20) reported three times the number of externalizing symptoms relative to those in the nonclinical group (Cohen’s d = 1.31). Externalizing symptoms may be a particular phenotypic feature of depression in men, and assessment of such symptoms may assist in the detection of those unwilling to disclose typical internalizing symptoms (i.e., sadness, hopelessness). Results also highlight the need for targeted research into stress-related and mental health outcomes of men in high health risk occupations such as truck driving.