Poverty, Inequality, and Awful Cities Could Literally Drive You Crazy

As the country moves forward in its conversation about mental health care in the wake of the Newtown massacre, a new study from the University of Cambridge reminds us that the causes of mental health disorders aren’t necessarily biological. As the research suggests, psychotic disorders like schizophrenia may also have roots in a person’s socio-economic environment -- especially when they are characterized by inequality, economic and social hardship, or high population density.

Over the last few decades, numerous studies controlling for factors like family history, age, education, sex, and substance use have demonstrated a strong link between living in dense, urban areas and an increased risk of non-affective psychotic syndromes, like schizophrenia, which can feature hallucinations, delusions, and thought disorder. (Affective disorders, by contrast—also known as “mood disorders”—include depressive disorders and bipolar.) Many scientific criteria for causality have been met along the way: Several studies by the Dutch psychiatrist and epidemiologist, Jim van Os, for example, have demonstrated that correlations between psychosis and family history change when a family is moved to more- or less-urban developments.

Led by Cambridge psychiatric epidemiologist James Kirkbride, the authors of the new study note that, despite the ample scholarship urbanicity to psychosis, much less is understood about what, exactly, makes the urban environment so apparently destabilizing. A number of biological environmental factors have been suggested over the years, from poorer nutrition to a lack of vitamin D and sunlight, to the ease of transmission in dense areas of diseases that can cause psychosis, like syphilis.

In part because those theories place a primacy on early-life development, Kirkbride and his colleagues decided to take a closer look at social environmental factors, which, they hypothesized, can shape a person’s mental health over an entire lifetime. For the study, they mined data on 427 subjects from the East London first-episode psychosis (ELFEP) study, all of them aged 18-64; each subject had experienced a first episode of psychotic disorder between 1996 and 2000 in one of three ethnically-diverse, inner city neighborhoods of East London.

In conjunction with 2001 census data, researchers used the ELFEP data to estimate the incidence of psychosis across 56 neighborhoods. After controlling for factors like age, sex and ethnicity, their findings uncovered three separate predictors for psychosis in a given neighborhood: increased population density, increased inequality between rich and poor, and an increase in overall “deprivation,” including social and economic resources.

Statistically, the results were fairly dramatic: a single percentage point increase in a given neighborhood of either economic inequality or deprivation correlated to a 4 percent increase in the incidence of psychosis. “Our research suggests that more densely populated, more deprived and less equal communities experience higher rates of schizophrenia and other similar disorders,” Kirkbride said in a press release. “This is important because other research has shown that many health and social outcomes also tend to be optimal when societies are more equal.” (Another recent study found that in cities with higher homicide rates, shootings can spread "like a disease," moving in 'diffusion-like processes' across the city.)

It is still unclear what kind of mental disorders may have been at play in the mind of Adam Lanza, the young man who murdered 20 young children and eight adults, including himself, on Friday in Connecticut. Newport, where Lanza had lived, is by all accounts a small town—an extended suburb of the greater New York area; it is unlikely that the factors specifically cited in this study had any bearing on what was obviously a gross state of mental derangement.

But emerging news makes it seem increasingly clear that Lanza suffered from some kind of mental disorder. (Lanza's brother told law enforcement that Adam was believed to suffer from a personality disorder and was "somewhat autistic.") And if there’s one takeaway from studies like the above, it’s that nurture, not only nature, probably plays a very significant role in the formation of the kinds of disorders that drove 24-year-old James Holmes to shoot up a movie theater in Aurora, Colo., last summer; or the psychosis that drove Jared Loughner to kill six people and wound 13 others, including former Arizona congresswoman Gabrielle Giffords in Tuscon last year.

That the individual circumstances of a person’s upbringing could affect someone’s mental stability—say, because of the proverbial abusive step-father—isn’t surprising. That there could be such a bold correlation between mental instability and an impoverished socioeconomic status is downright frightening, and belies the arguments of many a pro-gun advocate who say, in effect, that gun control is futile because we can’t prevent crazy. Studies like this suggest, again, that we can.

The findings also shed a new and interesting light on data I saw recently that was as disheartening as it was unsurprising: Not only does America almost lead the way in income inequality among rich nations, but there is a direct, if moderate, correlation between inequality and relative homicide rates. Add Americans’ relatively high access to guns, and America takes that gentle correlational trend and, pardon the pun, blows it away.

Different data and different thoughts from different places, perhaps: But it all adds up to one nasty stew we’re brewing.