A depression develops when overproduction, decreased demand, or a combination of both factors forces curtailment of production, dismissal of employees, and wage cuts. Unemployment and lowered wages further decrease purchasing power, causing the crisis to spread and become more acute. Recovery is generally slow, the return of business confidence being dependent on the development of new markets, exhaustion of the existing stock of goods, or, in some cases, remedial action by governments. Depressions and recessions today tend to become worldwide in scope because of the international nature of trade and credit.
Insufficient numbers of profitable investment outlets, overexpansion of commerce, industry, or agriculture, a stock-market crash, the failure of a great banking or industrial firm, or war may be among the precipitating factors of a downturn. In antiquity, and even up to the 18th cent., depressions had chiefly noneconomic causes, such as wars and weather-induced crop failures. From c.1700 to 1825 economic crises were in the main speculative or commercial; since 1825 they have been increasingly industrial, although the Japanese recessions of the 1990s were caused in part by reduced consumer demand.
The economic crises of the 20th cent. saw the entry of governments into large areas of the economy that had previously been in private hands. Job reeducation programs, government employment of the previously unemployed, and increased public welfare responsibilities are among the programs adopted to alleviate depressions. Moreover, by applying Keynesian economic principles to public policy, governments have sought to affect the business cycle directly and prevent depressions. Large-scale public works expenditure (pump priming), tax cuts, interest rate adjustments, and deficit spending during recession are among the measures that have been taken to reduce the severity of periodic economic downturns such as those experienced in the United States in 1982 and internationally in the early 1990s and 2000s. In the collapse of the U.S. housing bubble that began in 2007, the uncertainties associated with mortgage-related securities and other financial instruments that had pervaded the international financial system undermined or threatened a wide range of financial institutions, leading in 2008 to unprecedented measures by the Federal Reserve in an attempt to avoid a financial collapse and depression. Nonetheless, the resulting financial crisis and recession was the worst in the United States since the 1980s and also severely affected many other nations.
See also Great Depression.
See M. Bernstein, The Great Depression (1987); C. P. Kindleberger, The World in Depression, 1929-1939 (rev. ed. 1986) and Manias, Panics, and Crashes (rev. ed. 1989); W. C. Mitchell, Business Cycles and Their Causes (1989); A. W. Mullineux, Business Cycles and Financial Crises 1990).
Close to 20% of Americans are likely to suffer major depression at some time, and women tend to be more susceptible to the disorder than men. Major depression is likely to interfere significantly with everyday activity, with symptoms including insomnia, irritability, weight loss, and a lack of interest in outside events. The disorder may last several months or longer—and may recur—but it is generally reversible in the short run.
Bipolar disorder is much rarer, affecting only about 1% of the U.S. population; women and men tend to be equally susceptible. Its sufferers alternate between states of depression—similar to that which is experienced in unipolar disorder—and mania, which is characterized by intense euphoria and frenetic activity. Bipolar disorders are often interspersed with periods of relatively normal behavior, which may last for long periods of time between episodes of depression or mania. Manic-depressives have an extremely high rate of suicide, and episodes of the disorder tend to recur.
Medical evidence suggests that depressive states may be connected to deficiencies in the neurotransmitters norepinephrine and serotonin. Drug therapy includes various antidepressants that act on the flow of neurotransmitters and lithium for bipolar disorder (antidepressants can cause mania when used to treat depression in bipolar patients). There also has been success with electroconvulsive therapy (ECT) for major depression.
In recent years, theorists have argued that many depressed individuals depend upon others for their self-esteem, and that the loss of one of these emotional supports often precipitates a depressive reaction. A number of psychologists contend instead that depression is a result of learned helplessness, which occurs when a person determines through experience that his actions are useless in making positive changes. Other theorists have shown that genetic factors play a role in depression.
See L. Wolpert, Malignant Madness (2000).