Mental Illness & the EnvironmentM&

It is well-documented that human mental health emerges from a complex interplay between genetics, psychological, lifestyle, and other factors. In addition, people are also exposed to numerous environments. Mental illness contributes significantly to the global burden of mental disorders (i.e., 13% disability adjusted life-years lost). It is therefore important to grasp how and to what extent environmental exposures affect mental health outcomes. In the past year, 20% of all adults worldwide suffered from a mental disorder. Mental disorders have a lifetime prevalence of two out of seven adults and will continue to remain a leading cause of disease burden. Such disorders have devastating consequences for people’s quality of life and represent striking challenges for health systems as a whole. Thus, the reduction of mental disorders is a health priority in both developed and developing countries.

The geographic context of individuals is a central construct in assessing the contribution of environmental exposures to people’s mental health. While residential neighborhoods are frequently thought to represent an environmental context, this approach is increasingly critiqued because it assumes that people are immobile and exposed only to their residential neighborhoods. As this seems to be too restrictive an assumption, mobility-based environmental exposure assessments in mental health research have been put forward as methods that represent exposures more accurately. Such approaches highlight the importance of exposures that people experience throughout the day and over their lifetime.

Causes: Mental illnesses, in general, are thought to be caused by a variety of genetic and environmental factors:

• Inherited traits. Mental illness is more common in people whose blood relatives also have a mental illness. Certain genes may increase your risk of developing a mental illness, and your life situation may trigger it.
• Environmental exposures before birth. Exposure to environmental stressors, inflammatory conditions, toxins, alcohol or drugs while in the womb can sometimes be linked to mental illness.
• Brain chemistry. Neurotransmitters are naturally occurring brain chemicals that carry signals to other parts of your brain and body. When the neural networks involving these chemicals are impaired, the function of nerve receptors and nerve systems change, leading to depression and other emotional disorders.

Risk Factors: Certain factors may increase your risk of developing a mental illness, including:

• A history of mental illness in a blood relative, such as a parent or sibling
• Stressful life situations, such as financial problems, a loved one's death or a divorce
• An ongoing (chronic) medical condition, such as diabetes
• Brain damage as a result of a serious injury (traumatic brain injury), such as a violent blow to the head
• Traumatic experiences, such as military combat or assault
• Use of alcohol or recreational drugs
• A childhood history of abuse or neglect
• Few friends or few healthy relationships
• A previous mental illness

Mental illness is common. About 1 in 5 adults has a mental illness in any given year. Mental illness can begin at any age, from childhood through later adult years, but most cases begin earlier in life. The effects of mental illness can be temporary or long lasting. You also can have more than one mental health disorder at the same time. For example, you may have depression and a substance use disorder.

Complications: Mental illness is a leading cause of disability. Untreated mental illness can cause severe emotional, behavioral and physical health problems. Complications sometimes linked to mental illness include:

• Unhappiness and decreased enjoyment of life
• Family conflicts
• Relationship difficulties
• Social isolation
• Problems with tobacco, alcohol and other drugs
• Missed work or school, or other problems related to work or school
• Legal and financial problems
• Poverty and homelessness
• Self-harm and harm to others, including suicide or homicide
• Weakened immune system, so your body has a hard time resisting infections
• Heart disease and other medical conditions