Depression is a disease with a specific set of symptoms, notably a persistent feeling of sadness and loss of interest. Depression sufferers lose vitality, self-esteem and experience mood disorders. Depression is the cause of unreasonable and unnecessary suffering for millions of people, often to the point of disabling the sufferer. Depressed individuals usually struggle with completing their day-to-day tasks, feeling as if there’s no more point in living. 

Depressive disorders can be found throughout the world. Depressive patients account for a significant proportion of all those requiring mental heath care and, as the majority of them remain untreated, their suffering continues to disable them and to cause losses to their families and communities. The situation is especially severe in developing countries. Lack of adequate detection and treatment is due to poorly-trained health workers, scarce resources, and insufficient knowledge.

By 2020 depression will be the second most debilitating disease, yet in many parts of the world depression is stigmatized, with many people refusing treatment for fear of social backlash. Even so, tremendous strides are being made in the study and treatment of depression, including a better understanding of its causes and how best to treat it.

In psychiatry, a major depressive episode refers to a clinical syndrome consisting of lowering of mood-tone (feelings of painful dejection), and loss of interest or pleasure in all, or almost all, activities, most of the time for a period of at least two weeks. It is experienced as a paralyzing listlessness, dejection and self-deprecation, as well as an overwhelming sense of hopelessness. It is a pathological state of conscious psychic suffering and guilt, accompanied by a marked reduction in the sense of personal values, and a diminution of mental, psychomotor, and even organic activity, unrelated to actual deficiency. As used by the layman, the word depression refers to the mood element, which in psychiatry would more appropriately be labelled dejection, sadness, gloominess, despair or despondency. Dysthymia is the state just below the threshold for major depression.

A personality disorder exists when the habits that constitute a personality are inflexible and damaging. Inflexible and maladaptive personality traits can cause significant impairment in social or occupational functioning or subjective distress. In some cases, one may not realize that they have a personality disorder because thier way of thinking and behaving seems natural. And they may blame others for the challenges they face. Personality disorders usually begin in the teenage years or early adulthood. There are many types of personality disorders. Some types may become less obvious throughout middle age. 

Trade protectionism is the result of governments acting to save certain sectors of their economies from foreign competition. The impact of this on the fledgling industries is considerable but they are in no position to retaliate. Protectionist policies have also been directed by developed countries against each other, but this is usually carefully negotiated to avoid retaliation.

The degree of general health improvement achieved by public and private health services is not as high as might be desired. Although technical knowledge for achieving better health is available, in most countries this knowledge is not being put to the best advantage of the greatest number. Health resources are allocated mainly to sophisticated medical institutions in urban areas. Rather than better health for the average person, "improvement of health" tends to be equated with the provision of medical care dispensed by growing numbers of specialists, using narrow medical technologies for the benefit of the privileged few. At the same time, access of large segments of the world's population to health services is limited or non-existent; disadvantaged groups throughout the world have no access to any permanent form of health care. These groups probably total four-fifths of the world's population, living mainly in rural areas and urban slums.

In some countries, even though health facilities are located within easy reach, inability to pay or cultural taboos put them out of bounds. To complicate matters, health systems are often devised outside the mainstream of social and economic development, frequently restricting themselves to medical care, although industrialization and deliberate alteration of the environment are creating health problems whose proper control lies far beyond the scope of medical care. Such services operate in an isolated manner, neglecting other factors contributing to human wellbeing such as education, communications, agriculture, social organization, community motivation and involvement. This ignores the fact that health cannot be attained by the health sector alone.

In developing countries in particular, economic development, anti-poverty measures, food production, water, sanitation, housing, environmental protection and education all contribute to health and have the same goal of human development. The pace of technological and economic development requires an intensified release of human energy, placing heightened importance on physical stamina as a precondition. However, although the current diet upon which people exist may appear to be ample, it lacks the nutritional balance to sustain regular participation in a modernized society. In addition, a whole complex of issues such as safe water, refrigeration and basic hygiene remain relatively undeveloped and therefore continues to perpetuate illness that drains vitality. The sheer number of people in the care of one doctor, the remoteness of proper medical facilities and the high cost of treatment prevent early detection of disease; continuation of energy-draining low-grade infections results in either long-lasting or permanently chronic defects. The care of the physical well-being of rural people when called upon to make such efforts at development is a crucial factor that cannot be neglected.

Relatively sudden and widespread disturbance of the social system and life of a community or region may be caused by one or more of the destructive forces of nature. Natural disasters are usually the result of geophysical or meteorological disturbances, the causes and mechanisms of which are now relatively well understood even though their occurrence and the detailed consequences cannot be predicted. The phenomena which mainly cause disasters are earthquakes and cyclonic storms, usually of tropical origin, but seismic activity under the sea can cause floods far from the centre of disturbance. Besides direct damage due to flooding, wind forces and earth movement, landslips and outbreaks of fire may occur to cause further damage and loss of life. Volcanic activity, besides being the cause of some earthquakes, can also cause damage from lava and ash.

The UNEP data book of 1991 notes that the frequency of natural disasters has increased in recent decade, adding that one reason may be a heightened awareness of disasters through reports in the media. It also suggests that natural disasters are becoming more significant in terms of magnitude and numbers. The most widely accepted reason is that the "hit rate" has increased considerably due to the continuing growth of world population. More than one third of the world's largest and fasting growing cities are now in regions of high seismic risk. Many of these are in developing countries where poor construction methods exacerbate the dangers. Many huge populations of non-urban people are concentrated in regions of environmental risk, such as variable rainfall; thousands of people have migrated to these regions in the past few decades as a result of population pressure and social conflict.

The world's societies and environment are increasingly suffering from the effects of natural disasters. A disaster usually results from the combination of a vulnerable environment and a hazard such as floods, tropical storms, earthquakes, landslides, wild fires, volcanic eruptions, and tsunamis. They can cause the loss of life, property and livelihoods.