Lack of education, employment and income (deprivation), high crime and inequality (the gap between rich and poor) are characteristics of urban societies with generally high population density. Although cause and effect cannot be fully teased out, the high correlation seen between mental diseases and these types of habitats suggest, at the very least, a strong environmental effect on mental diseases. Treatment of CNS disorders by chemical means has been controversial. For example, a recent report shows that the perpetrators of the last two dozen mass killings in the US were on medication. If the environment is the primary cause of mental health issues, then, both the diagnosis and the treatment of these diseases need to be rethought.
More importantly, society has to assess the total cost of design and redesign. If the status-quo designs lead to segmentation in which certain parts of the system unavoidably pick up higher levels of deprivation, density and inequality and related high costs due to mental diseases, it is important to consider alternatives. The self reinforcing nature of sick societies leading to sicker inhabitants means that breaking this cycle is hard. Investing into improving these environments and their characteristics could have high return to society if all costs are considered.
The apparent connection between mental health and societal characteristics is an important notion. Both researchers and policy-makers need to consider this in their work.