According to the World Health Organization (WHO), clinical depression affects nearly 300 million people worldwide. The Centers for Disease Control (CDC) estimates that 20 million or more people in the U.S. have depression at any given time, while more than 18 percent of U.S. adults report depression at some point in their lives and .more than 12 percent of adults report significant feelings of anxiety.

Treatment for depression is of limited effectiveness; only 30-40 percent of those initially treated experience full resolution of symptoms, or remission. What's more, studies show, successive efforts to achieve remission are less and less effective.

Understanding the underlying biology of depression, anxiety, and related conditions such as post-traumatic stress disorder (PTSD) is necessary for making correct diagnosis and planning effective treatment. But especially in psychiatry, given the complexities of the brain, diagnosis and treatment are not yet well-grounded in biological understanding.

Medical treatment is ideally based on a number of factors, including knowledge of the disease process, the ability to make accurate diagnoses, and an understanding of how individual factors affect treatment planning and outcome. The National Institutes of Health started the BRAIN Initiative (Brain Research Through Advancing Innovative Neurotechnologies) in 2013, calling for neuroscience-based models of disease and health. Understanding the causal factors of disease suggests the levers clinicians can manipulate to provide the most effective treatment possible.

Psychiatric diagnosis in the United States is currently based on the Diagnostic and Statistical Manual of Mental Disorders (DSM-5). Although efforts have been made to improve its approach with more specific criteria for mental illness based on statistics and available data, the DSM is not firmly scientifically based. For the vast majority of illnesses described, the diagnostic criteria say little to nothing about the cause of the disease; instead, they primarily reflect long-observed clinical patterns, rendering the DSM a work in progress and of less-than-desirable utility........

© Psychology Today