Mental illness affects so many people, yet studies on mental illness are often small and focus on just one type of condition. Looking at the big picture may be necessary to fully understand the nature of mental illness and its treatment.
A recent study found that the rate of different types of mental disorders varied according to age and sex in a national population.
The researchers concluded that the understanding of mental illness trends and patterns in a large population can influence governmental healthcare spending and research.
The lead author of this study was Carsten Bøcker Pedersen, DrMedSc, of the National Centre for Register-Based Research and the Centre for Integrated Register-Based Research at Aarhus University and The Lundbeck Foundation Initiative for Integrative Psychiatric Research — all in Aarhus, Denmark.
This study included all people born in Denmark between January 1, 1990 and December 31, 2010 who were still alive on January 1, 2000 — roughly 5.6 million people.
The researchers used the Danish Civil Register System to gather demographic data, and the Danish Psychiatric Central Research Register to identify cases of psychiatric disorders that were treated at a psychiatric center.
The researchers followed up with participants between 2000 and December 31, 2012, or until first-ever treatment for a mental disorder in a psychiatric care setting, death or moving away from Denmark.
Of all the study participants, 320,543 started psychiatric treatment during the study period, 489,006 died, and 69,987 moved away from Denmark.
The researchers found that 38 percent of the women and 32 percent of the men received psychiatric treatment for the first time for any type of mental disorder. This finding means that approximately one out of three Danish people entered psychiatric treatment for any type of mental disorder.
The findings showed that the rate of different mental disorders varied according to age and sex.
Men were more likely to receive treatment for disorders such as autism, hyperkinetic disorders (e.g., ADHD), schizophrenia, and substance abuse disorders.
Women were more likely to receive treatment for disorders such as anxiety, mood disorders (e.g., Depression, Bipolar Disorder), and eating disorders.
The researchers discovered that the peak age of onset for organic mental disorders (decreased mental function due to a medical disease other than a psychiatric illness) was around 80 years old.
The peak age of onset of substance abuse disorders and schizophrenia was between the ages of 10 and 30 years.
Mood disorders had two peak ages of onset, the highest around 20 years old and then from 80 to 90 years old, suggesting that these types of disorders were related to many different types of events and circumstances.
Dr. Pederson and team believe that these findings should help influence how future health care funding should be used.
This is the first study to look at lifetime patterns and trends for multiple mental illnesses in a national population.
There were a few limitations to this study. First, register-based studies do not consider people with untreated disorders. Second, diagnoses could not be validated. Third, the study included people from Denmark, a country that pays for all citizens' health care; therefore, these findings may not be generalizable to places where citizens have to take on more of a financial burden. Fourth, only people who sought out treatment were considered.
This study was published on March 26 in JAMA Psychiatry.
The Stanley Medical Research Institute, the Lundbeck Foundation, the National Health and Medical Research Council and the National Institute on Drug Abuse provided funding.