Thus even though these two

Thus, even though these two phenomena – PE and/or NDO – may be more prevalent in the youngest group, they may not have strong adverse health effects over time, because individuals advance, or expect to advance in their careers. Those who were in less desired and more precarious employment in their early twenties, for example, may thus be in good health when followed up in their early thirties. This, however, may not be the case for those who have health problems already from the beginning. Evidence shows that impaired health in itself is a hinder to get into more permanent employment and advance in an occupational career (Paul & Moser, 2009). At a later stage in life, having achieved permanent employment and advancing in a desired occupational career could be expected to constitute the ‘normal’ situation. However, those who, when entering midlife, are still in NDO or have PE may be less satisfied and more worried about their employment situation (Wyn & Andres, 2011). Towards the end of the occupational career, many may be in the most secure and permanent employment positions. Yet, during the later stages of a career, age-related health problems can increase and long-term adverse health effects of working in certain occupations could also become more pronounced. For example, older workers may lack the physical capabilities to perform low-complexity jobs, whereas they might have the experience and skills to perform jobs with higher autonomy or possibilities to pass their knowledge on to others (Truxillo, Cadiz, Rineer, Zaniboni & Fraccaroli, 2012). Furthermore, it dna stain could be argued that over time, occupational careers and job demands change, and particularly the older workforce may begin to feel that they lag behind in the latest developments and technologies. In part, this could also relate to the fact that older workers seem to be less willing to participate in training and career development activities (Ng & Feldman, 2012). Moreover, ageism, or negative social stereotypes about older people, can lead employers and managers to inadvertently undervalue older workers’ skills and experience (Poscia et al., 2016). All this may be reflected in a decreased willingness among older workers to continue in the same occupation. However, since many older workers doubt their employability on the labour market (Bernhard-Oettel & Näswall, 2015) or simply feel that it is too late to become re-educated and start a new occupational career, they might more often choose to endure the situation, or perhaps even retire early. Nevertheless, working in a NDO and continuing to do so because there are no better alternatives may have negative health effects over time. Summing up, there is reason to believe that neither NDO nor PE prevalence is uniformly distributed throughout the working career. Furthermore, their impact may vary considerably across the life course. To our knowledge, even though the occurrence of each of these two phenomena may influence the occurrence of the other, they have not been investigated together previously since the original study by Aronsson et al. (2000), nor has a life course perspective been applied.
Methods
Results The proportion of individuals with poor mental health in the study population decreased slightly over the follow-up period, with 24% GHQ-cases in 1999/2000, 23% in 2005, and 19.5% in 2010. As can be seen in Table 2, being exposed in 1999/2000 or in 2005 at least once to NDO, as well as being exposed at least once to PE, were both more common in the youngest age group than in the middle age group, which in turn were exposed to higher degrees than those in the ‘oldest age group’. Table 3, with results from the entire group, confirmed that young age was related to poor mental health at follow-up in 2010, as was female gender. Both NDO and PE were related to the outcome. The age-adjusted IRR of the dichotomised version of NDO (i.e. NDO in 1999/2000 or 2005; yes vs. no) was 1.4 (1.2–1.6) and the corresponding figure for PE was 1.5 (1.2–1.7). However, there was no clear-cut tendency for a stronger relationship between poor mental health and being exposed twice (1999/2000 and 2005) vs. once.