Two large hurricanes have bashed the east coast of the United States as a third threatens U.S. territories, causing damage likely to eclipse that of Hurricane Katrina, the most expensive natural disaster in U.S. history which killed 1,600 people and forced the evacuation of over 500,000 others. But as the storm waters recede, research tells us that communities will be hit by a wave of mental health problems as residents experience a sharp rise in anxiety disorders, depression, and post-traumatic stress disorder (PTSD). What we have learned from Hurricane Katrina could help blunt some of these effects.
Five months after Hurricane Katrina, the first analysis of the mental health effects found that 17 percent of New Orleans residents reported serious mental illness in the first month after the storm devastated their city. This compares to 1 to 3 percent of the general population reporting such illness in any given month. Around half of these residents described increased anxiety, but the most common illness was PTSD, often linked to the trauma of loss of property as well as robberies and assaults, which jumped in incidence after the hurricane.
In the U.S., PTSD has a prevalence of around 6%. While most people hear about the problem in combat veterans, it can occur in 25-35% of people who experience severe trauma such as assault or a natural disaster. Studies find that around 30-40% of the risk of PTSD is genetic and that trauma actually changes how the brain works by altering the brain’s fear pathway. This is the same brain circuitry that is important for learning.
Researchers updated this initial analysis by evaluating survivors from Alabama, Mississippi and Louisiana, around six months after hurricane Katrina landed. They found that less than one-third of survivors with anxiety disorders received care, and more than half with more severe disorders received no help at all. For those who did get help it was usually inadequate and infrequent, with more than half dropping out of treatment. These numbers track with a previous study of survivors of the World Trade Center attack on 9/11 which found that only 36% of people suffering from probable PTSD or depression sought mental health care within six months of the event.
A year after Katrina, the number of survivors with PTSD had jumped from 15% to 21%, another study reported, and the percentage of people experiencing suicidal thoughts had rose from 2.8% to 6.4%. A clear trend in all these studies is that access to resources—such as mental health services and stable living facilities—appeared to ease mental illness in survivors.
This apparent trend in resource access being critical for recovery became clear in a study of the most vulnerable residents of New Orleans—low-income, single mothers, who were mostly African-American. In this case, researchers had initiated the study before the hurricane hit as part of a project to understand low-income women attending community college. This means that researchers had baseline data on these women and could directly compare their mental health before and after the hurricane. Among this group, nearly half had probable PTSD a year after Katrina, and a surprising number reported poor physical health, a sign that the added stress of caring for a small child in the wake of a natural disaster was affecting them physically as well.
What is even more troubling is that when researchers contacted these women nearly five years after Katrina, many still had not returned to baseline mental health. When asked how often they thought about the hurricane in the prior week or if they had thoughts about the storm they could not suppress, around 33% showed signs of post-traumatic stress and 30% had psychological distress. While other studies have found that natural disaster survivors tend to bounce back after a year, these researchers found that, for some people, the effects can be very long lasting.
We know psychological trauma can have long-lasting effects on how neurons function and how the brain responds to stress. This is because the trauma that leads to PTSD directly impacts the brain by altering the action of the DNA in neurons, in a process called epigenetics. This is the process by which DNA is made to express genes, to turn them on or off, without altering the basic genetic sequence of the DNA molecule.
Thankfully, we have some hints from studies of Katrina on how to deal with the coming crisis in mental health that will certainly wash up on the shores of Houston and communities in Florida. First, we need to provide care as soon as possible to people who develop mental illness in reaction to this natural catastrophe. In the case of Katrina, after health clinics flooded, mental health experts set up clinics on cruise ships that were docked on the Mississippi River. Second, providing survivors with social services to find housing, jobs, and ways to get their lives back to normal creates a sense of stability. And when people feel safe, their stress levels fall.
But after addressing this immediate crisis, we need to think about funding research to help us better deal with difficult illnesses like PTSD. The federal government estimates that around 8 million American adults manifest this illness during any given year, but the only drugs the FDA has approved for treatment were actually developed to treat depression and they are not adequate. We need better studies to understand how this type of trauma changes our brains, and find better treatments.