Do we know so far whether neuroticism declines with age?
I found contradictory sources about the evolution of neuroticism across the life span.
That is, after emerging in childhood, neuroticism remains relatively stable before showing gradual age-related decreases that continue into old age (Eaton, Krueger, & Oltmanns, 2011; Roberts & Mroczeck, 2008; Roberts, Walton, & Viechtbauer, 2006)
The one exception was that Neuroticism was slightly negatively associated with age in the BHPS [British Household Panel Study] and slightly positively associated with age in the GSEOP [German Socio-Economic Panel Study].
There is also this graph displaying the evolution of emotional stability across the life span