coping with daily life. Anxiety disorders are characterized by feelings of anxiety and fear. They can be broadly described as a group of disorders in which anxiety is induced in situations that may or may not be well defined. These situations often produce a feeling of strong avoidance, or they are endured with apprehension. Examples of physical symptoms include palpitations, shortness of breath, or feeling faint, and they are often accompanied with irrational thoughts, such as fears of dying, losing control, or going mad. Anxiety and depression are often coexistent conditions. 23 Data from 2015 indicate the prevalence of depression to be 4.4%, and more prevalent in females. This is roughly 322 million people worldwide. Prevalence appears to peak around older adulthood, 55-74 years. Between 2005 and 2015 there was an 18.4% increase in the number of people living with depression. In the United States in 2009, US$22.8 billion were spent on the treatment of depression with the loss of productivity estimated at US$23 billion in 2011. 24 The prevalence of anxiety disorders is around 3.6% and again more common in females, equating to 264 million people worldwide.Interestingly, prevalence does not vary considerably between age groups. The largest single contributor to nonfatal health loss is depressive disorders. 25 Mental health disorders have been associated with cardiovascular disease and diabetes mellitus. This may be through lifestyle factors, such as smoking, reduced activity, poor diet, obesity, hypertension, or a lack of adherence to health programs or advice commonly seen in patients with mental health disorders. Though biological effects may be due to alterations in neurotransmitter and hormone levels such as serotonin and cortisol, which influence the immune response, systemic inflammation may also play a role through bidirectional relationships. 26 Risk factors for depression in adults include sex, age, race/ethnicity, education, marital status, geographic location, employment status, chronic illness, substance abuse, and family history of psychiatric illness. 24 Exposure to traumatic childhood events is now recognized as an antecedent to future major depressive disorder. The risk factors in older adults are slightly different and reflect a greater age. They include disability, complicated grief, chronic sleep disturbance, loneliness, and a history of depression. Different factors may influence the relapse and recurrence of depression than those that influenced the initial onset. Moreover, major depressive disorder is associated with poorer health and earlier death. This includes a higher prevalence of heart disease, diabetes, obesity, cognitive impairment, disability, and cancer. In addition, unhealthy lifestyles are common, with poorer self-care and adverse effects of medications.
| Biological mechanisms to explain mental health disordersNo established mechanism can explain all aspects of depression. 27 Major depressive disorder clusters within families, with a threefold risk for first-degree relatives and...
