Ten years ago this month, Hurricane Katrina made landfall along the Gulf Coast, claiming more than 1,800 lives and damaging more than $100 billion in property in a mass tragedy that captured the attention of the world.
But long after the news crews left New Orleans, the consequences of Katrina continued to play out -- not just in the well being of area residents, but in the larger understanding of the impact that disasters have on population health. It has become increasingly clear in the last decade that community-building supports and long-term mental health assistance improve resilience after mass disasters.
Katrina pushed us to consider new ways of reaching hard-to-reach populations; now, the challenge is to keep that momentum going, so that the lapses in our initial response to Katrina are never repeated.
The number of disasters worldwide -- both natural and human-made -- is increasing, principally as a result of global climate change and urbanization. In 2012, there were almost 905 natural catastrophes registered worldwide. China is the country most frequently affected, followed by the U.S., the Philippines, India, and Indonesia. In the U.S., an estimated 13 to 19 percent of adults have reported having experienced a disaster in their lifetime.
Between 2003 and 2012, natural disasters killed an average of 106,654 people each year. The burden of disasters includes lost life, infrastructure damage, monetary loss, years lost to disability, interruption of services, and injuries. Physical injuries and death are usually immediate, happening within minutes of the event. But they also are very much the "tip of the iceberg" -- a small fraction of the health burden that principally involves mental health, and that can be long-term and debilitating.
In reviewing literature on PTSD (post-traumatic stress disorder) with colleagues, I previously found that 30 to 60 percent of direct victims of disasters experience PTSD. This prevalence was smaller (10 to 15 percent) among rescue workers, and about 5 to 10 percent in the general public. PTSD prevalence varies greatly between studies due to different measures, with many studies finding PTSD symptoms to be associated with younger age, female gender and a history of mental illness.
The risk of depression and substance use is increased after disasters. Alcohol and substance use disorders are more prevalent among men after disasters, and are often used as a coping mechanism. Many studies found increased use of alcohol, cigarettes and drugs in New York City after the September 11 terrorist attacks. A study of Hurricane Sandy survivors in New Jersey found that high hurricane exposure, physical health limitations and environmental health concerns were all associated with worse mental health outcomes. Other risk factors found to be associated with post-hurricane health include ongoing stressors, lower social support, and financial loss.
It is worth emphasizing that the majority of people who are faced with disaster tend to be resilient, or to continue normal functioning relatively quickly after experiencing a traumatic event and initial mental health symptoms. Longitudinal work allows us to see this phenomenon over time; for example, Pietrzak and colleagues followed Hurricane Ike survivors at three time points after the storm and found that the prevalence of any past-month mental disorders and hurricane-related PTSD decreased over time. Most studies suggest that the course of mental health after these events is different for different groups of people.
In the immediate aftermath of a disaster, the most important services for traumatized populations are those that help them to return to normal -- materially and psychologically. The long-term goal is to prevent those traumatized by an event from allowing it to affect the rest of their lives.
It is increasingly clear that context plays a role in shaping this intervention. Community-wide destruction was shown to worsen post-traumatic stress in post-tsunami Indonesia, regardless of the levels of individual exposures and loss. On the other hand, community social capital, or social bonding through community institutions and organizations, can promote resilience in individuals. Displacement and lack of order in a community increases the likelihood of violence, especially violence towards women and children. At a more macro level, disasters in lower-income countries are associated with worse health outcomes.
There is also growing interest in population behavior after disasters. A colleague and I recently suggested a model of population behavior following large-scale disasters, based on a set of 339 events from 1950 to 2005. There are five overlapping stages in this model: group preservation, which involves directly affected people seeking information and taking action to preserve life and secure safety; population preservation, which includes actions by the larger population; internalization, after the initial danger has passed, which involves mourning losses and recognizing a new set of norms; externalizing, which involves seeking redress and addressing vulnerabilities; and renormalization, which involves cultural adaption to post-disaster circumstances. The last phase ends when new modes of behavior, such as security policies or technological improvements, become regular.
Each of these stages can both affect mental health and offer opportunities for targeted interventions. For example, volunteerism in the early stages may improve the mental health of those outside the directly affected circle. There are other suggested models of behavior after disasters, including those that focus on community response, as well as evidence-based post-disaster policy recommendations. These all warrant further study and refinement, so that we can better serve the communities who face these challenges.
A decade out from Katrina, we still have work to do to ensure that our response to disasters continues long after the news crews have moved on. It is, sadly, in the period after the initial burst of attention that much of the damage wrought by disasters comes about. I am frequently asked, after a disaster has occurred, what one can do to help from a distance. It is a difficult question, but I often recommend providing support to organizations that are committed to helping societies rebuild in the medium- and long-term aftermath.
The treatment for people who suffer post-disaster mental health consequences grows more complex over time. Prevention and intervention aimed at helping as many people as possible return to a semblance of normal life are critical.