Post-traumatic stress disorder (PTSD) is a condition that can arise in individuals who have experienced shocking, dangerous, or frightening events.
After a trauma, it is normal to experience a range of reactions. However, in PTSD, these reactions persist and last for months or even years.
Symptoms vary from individual to individual, but one of the most prominent and upsetting symptoms is known as re-experiencing.
Re-experiencing refers to repetitive flashbacks of the event, bad dreams, and frightening thoughts.
Experts believe that re-experiencing might be an early marker of mental pathology.
During the events that took place at the World Trade Center (WTC) on the 11th September, 2001, many responders - firefighters, police, and public - experienced a range of traumas.
According to the authors of the current study, around 20 percent of these responders subsequently developed PTSD.
In July 2002, the Centers for Disease Control and Prevention (CDC) began a monitoring and treatment program for WTC responders. Since it began, more than 33,000 individuals have enrolled in the WTC Health Program.
Researchers from Stony Brook University in New York City took a sample of individuals that attended Stony Brook clinics between January 2014 and April 2015. In all, 818 responders (average age 52.8 years) were screened. Researchers assessed the participant's concentration, reasoning, memory, and problem-solving abilities.
Each individual was also checked by psychologists to diagnose PTSD and major depressive disorder (MDD).
"To our knowledge, this is the first study to examine the association of PTSD and MDD with cognitive impairment in a large group of civilian World Trade Center responders without head injury."
Senior author Sean A. Clouston, Ph.D.
Cognitive effects of 9/11 on responders
The CDC's dataset of WTC responders is a unique opportunity to understand more about PTSD and how it can impact an individual's cognitive performance over time.
Below are the headline findings of the study:
- 12.8 percent of responders had scores indicating cognitive impairment, and 1.2 percent had scores that suggested possible dementia
- Both MDD and PTSD were associated with cognitive impairment
- Re-experiencing symptoms were strongly associated with cognitive impairment.
If the percentages taken from this research are scaled up to the 33,000 responders currently signed up with the CDC, they translate to 3,740-5,300 individuals with cognitive impairment and 240-810 with dementia.
"These numbers are staggering, considering that the average age of responders was 53 during this study. If our results are replicable, doctors need to be aware of the impact of cognitive impairment among individuals who have experienced traumatic events leading to PTSD.
For example, cognitive impairment can compound the course of PTSD and depression, impairing the person beyond the impact of PTSD itself."
Sean A. Clouston, Ph.D.
Delving further into the data
Clouston and his team made a number of other interesting discoveries:
- Responders were more likely to show cognitive impairment if they had lower education levels, non-law enforcement occupations, were older, and were current smokers
- Individuals who had severe early re-experiencing symptoms were more likely to go on to be diagnosed with MDD and PTSD; this backs up the theory that re-experiencing is an early sign of mental pathology
- PTSD and MDD were significantly associated with cognitive impairment, even after controlling for factors such as occupation, education, smoking status, trauma severity, hypertension, obesity, respiratory disease, and diabetes.
The authors also recognize some shortfalls in the research, including the fact that the sample was not random - participants had been selected for screening. Also, the study did not take into account previous head injuries; future studies should investigate whether earlier head trauma could play a role in PTSD's relationship with cognitive impairment.
PTSD affects an estimated 7.7 million Americans; the more information researchers can unearth, the easier it will be to design effective treatment and support. The CDC's WTC data set will be a vital tool in this quest for understanding.
Cognitive impairment among World Trade Center responders: Long-term implications of re-experiencing the 9/11 terrorist attacks, Sean A.P. Clouston et al., Alzheimer's & Dementia: Diagnosis, Assessment & Disease Monitoring, doi: http://dx.doi.org/10.1016/j.dadm.2016.08.001, published online 29 August 2016.
Alzheimer's Association news release, accessed 30 August 2016 via EurekAlert.
Additional source: Anxiety and Depression Association of America, Facts & statistics, accessed 30 August 2016.
Additional source: National Institute of Mental Health, Post-traumatic stress disorder, accessed 30 August 2016.