Despite economic development and amazing progress in medical knowledge and technology, the rates of mental illness remain high in the United States. In fact, they are on the rise for a number of conditions. The reasons for why the numbers are going up remain controversial. Are the rates of mental illness really increasing or are we overdiagnosed?
The increase in the rates of chronic diseases is less controversial and easier to demonstrate and explain. Diabetes, for example, involves numbers and lab results, such as glucose and insulin levels, while mental illness involves descriptions of symptoms. The rise in chronic diseases related to diet, inflammation, and environmental toxicities may have something to do with the increases in the rates of mental illness. Studies have shown that people with diabetes, and a number of other chronic diseases, have higher risk for depression than those without diabetes. Research is increasingly pointing to inflammation as a driving force in a number of chronic diseases, and also in mental health conditions. A large study from Denmark found that individuals with an autoimmune disease are 45% more likely to have a mood disorder, and that history of an infection increased the risk of a mood disorder by 62 percent.
The Heavy Burden of Mental Disorders
Mental illness results in disrupted thinking, mood, and behavior. It can cause the loss of emotional, mental, and physical freedom, and in some cases, premature death from suicide, violence, chronic illness, and side effects from medications. In addition, the rates of chronic diseases such as diabetes and cardiovascular disease are significantly higher in those with mental illness.
Mental illness not only affects individual health and wellbeing, but also society at large. In a large-scale study conducted by the World Health Organization, The World Bank, and Harvard University, mental illness ranks second only to cardiovascular illness in terms of the burden of disease in developed countries. When substance use disorders are included under the umbrella of mental illness, the burden of mental illness far outweighs the burden of all other illnesses. Major depression is second only to ischemic heart disease in terms of burden that a single illness causes for individuals and society. Alcohol abuse, drug abuse, schizophrenia, bipolar disorder, obsessive-compulsive disorder, panic disorder and post-traumatic stress disorder are the other main illnesses considered in this study.
High Rates of Mental Illness in the U.S.
Rates of mental illness in the United States are high now, and they were high before as well. Data taken from two large epidemiologic surveys, The Epidemiologic Catchment Area (ECA) study of the early 1980s and the National Comorbidity Survey (NCS) of the early 1990s, shows that 22% of adults experience a mental illness in a one-year period. An additional 6% of the population experiences an addictive disorder in a one-year period. A 2009 study by SAMHSA estimated that there were 45.1 million, or 19.9 percent of all adults, in the United States with any mental illness in the past year .
Overall, half of the population will develop at least one mental disorder in their lifetime.
Children experience similar rates of mental illness to adults, with an estimated 20-22% of children 9 -18 years old experiencing a mental illness over the course of a year. Considering the early age of onset for many mental disorders (6 years for anxiety, 11 years for behavioral problems, 13 years for mood disorders, and 15 years for substance use disorders), childhood is a key time for prevention and early intervention (Merikangas et al 2010; Friedman et al., 1996b, Surgeon General 1999).
It is hard to know whether the overall rates of mental illness are trending up or down as the much criticized Diagnostic and Statistical Manual (DSM) diagnostic criteria for mental illness continue to be refined. Results from older studies cannot be compared to newer studies because the diagnostic categories and research methods have not been consistent. Some older studies show rates of mental illnesses similar to those reported today. The 1954 Midtown Manhattan Study estimated that 23% of the adults in the sample had an “impaired” level of mental health that corresponded to a clinically significant need for treatment (Srole et al, 1975). While the exact rates of specific mental illnesses vary from survey to survey, overall they appear to be high yet stable, with increases for a few disorders.
Increasing Rates of Depression
Depression can present with many different symptoms, however, some of the most frequently observed symptoms are: feeling sad or “blue”, appetite changes with weight gain or loss, insomnia or sleeping too much, concentration problems, fatigue, hopelessness, negative thoughts, loss of interest in activities that used to be pleasurable and suicidal thoughts.
Based on a study which pooled data from two other studies, and included face-to-face interviews and consistent diagnostic criteria and research methods with a sample of 42,000 U.S. adult participants, the prevalence of major depression increased from 3.3% in 1991-1992 to 7% in 2001-2002. This was true across sociodemographic subgroups of the population. Based on these numbers, the prevalence of depression more than doubled in the 10-year period of this study.
Depression is one of the mental disorders linked to inflammation, and recently a number of research studies explored the use anti-inflammatory drugs to treat depression with promising results. It is possible that the increases in depression rates could reflect that Americans are more inflamed as a nation, rather than more pessimistic.
Increasing Rates of Autism
According to data from the CDC Autism and Developmental Disabilities Monitoring (ADDM) Network, the rates of autism are increasing. ADDM estimates the prevalence of autism spectrum disorders (ASD) among 8 year old children, whose parents or guardians reside within the 14 ADDM sites in the United States. Their study relies on professional and family reporting of autism diagnosis, and on a review of the children’s health evaluation records to determine the presence of Autism Spectrum Disorder (ASD) symptoms.
This study estimated the autism spectrum disorder rates as:
2002: 1 in 155 children
2006: 1 in 110 children
2008: 1 in 88 children
2010: 1 in 68 children
This data shows dramatic increase in autism rates. These results are consistent with the results of other studies about autism in the U.S. The data from the National Health Interview Survey demonstrated a nearly fourfold increase in estimated autism spectrum disorder prevalence between the 1997–1999 and the 2006–2008 surveillance periods. The rise in autism rates is not unique to the United States. Studies conducted in Britain and South Korea revealed autism spectrum disorder rates even higher than those in the U.S.
Autism is another disorder where environmental factors and diet are suspected to play a role. The research evidence available so far is pointing to a role of inflammation in autism. A recent review study published in the American Journal of Child and Adolescent Psychiatry found that of the 67 studies included in the review, the evidence for a proinflammatory state was strongest for autism spectrum disorders. Many parents of autistic children know that diet plays a role in their children’s symptoms, and inflammation may help to explain how diet is connected to autism. Children may be modern society’s unfortunate canaries in the coalmine signaling that something harmful is happening to our brains.
Increasing Rates of Attention Deficit Disorder
The rates of Attention Deficit Hyperactivity Disorder (ADHD) have also increased in recent decades. Based on data for children aged 3-17 from the 1997–2008 National Health Interview Surveys, which are ongoing nationally representative samples of US households, the prevalence of ADHD increased by 33% in one decade. In 1997-1999 the reported prevalence of ADHD was 5.69%, while in 2006-2008, that number jumped to 7.57%.
While the increase in ADHD rates may be partially connected to the changes in diagnostic critieria, environmental factors, diet and inflammation may also play a role in the increase in the rising rates of ADHD.
Clinicians, scientists and the general public continue to debate whether the increasing rates of mental illness reflect heightened awareness, improved access to services, an expansion of diagnostic definitions, or an actual increase in incidence of these diseases. There are multiple causes for the increases in mental disorders, and changes in the rates of chronic diseases, inflammation, and the various causes of inflammation such as diet and toxins, are likely suspects.
Friedman, R.M., Katz-Leavy, J.W., Manderscheid, R.W., et al. (1996). Prevalence of serious emotional disturbance in children and adolescents. In: Manderscheid, R.W., Sonnenschein, M.A. (eds). Mental Health, United States, 1996. Rockville, MD: Center for Mental Health Services, pp. 71-89.
Merikangas, K.R., He, J.P., Burstein, M., Swanson, S.A., Avenevoli, S., Cui, L.,Swendsen, J. (2010). Lifetime prevalence of mental disorders in U.S. adolescents: Results from the National Comorbidity Survey Replication – Adolescent Supplement (NCS-A). J Am Acad Child Adolesc Psychiatry, 49(10), 980-989. doi: 10.1016/j.jaac.2010.05.017. Epub 2010 Jul 31. http://www.ncbi.nlm.nih.gov/pubmed/20855043
Srole, L., Langner, T.S., Michael, S.T., Kirkpatrick, P., Opler, M.K., & Rennie, T. (1975). Mental Health in the Metropolis: The Midtown Manhattan Study. New York:New York University Press.
U.S. Department of Health and Human Services. Mental Health: A Report of the SurgeonGeneral. Rockville, MD: National Institute of Mental Health, 1999.