Depression is the common term for a group of mental health conditions\u2014called depressive disorders\u2014that produce mood disturbances capable of seriously or severely restricting an individual\u2019s ability to function in his or her daily life. As a rule, the specific symptoms of the depressive disorders vary in number and intensity from person to person. In a study published in August 2013 in the journal JAMA Psychiatry, a multi-institution research team tracked the number of depression symptoms that typically appear at various stages of adulthood. These researchers found that the rate of depression symptoms spikes in early adulthood, decreases for roughly two decades, and then spikes again in old age.\r\nDepression Symptom Basics\r\nThe National Institute of Mental Health lists common depression symptoms that include a restless or irritable mood, a persistently pessimistic or hopeless point of view, ongoing feelings of emptiness or anxiousness, recurring feelings of helplessness or guilt, a notable decline in memory or other basic mental skills, an unusual or unexplained drop in normal resilience or energy levels, an unusual rise or drop in food intake, problems staying awake or falling asleep, and the presence of suicide-oriented thoughts or behaviors. Additional common symptoms include lack of interest in pursuing pleasurable or enjoyable activities and a variety of physical complaints, including such things as headaches, muscle aches or abdominal discomfort. In order to qualify for an official diagnosis of major depression or any other depressive disorder, an affected individual must have a certain number of symptoms that are severe enough to impair the ability to function normally or follow a life-sustaining daily routine. However, not all people have the same depression symptoms or have symptoms of equal intensity, even within the criteria used to diagnose any single depressive illness. In addition, the number and intensity of symptoms may fluctuate within any one person over time. Some people have depression symptoms that alter their moods considerably, but don\u2019t have enough of these symptoms to qualify for a depression-related diagnosis.\r\nVarying Adult Rates\r\nIn the study published in JAMA Psychiatry, researchers from the National Institutes of Health and several universities used information from a project called the Baltimore Longitudinal Study of Aging to examine the changing rate of depression symptoms in a group of 2,320 adults between the ages of 19 and 95. In addition to the general level of symptoms, the researchers looked at three symptom subsets: a depressed mood, headaches or other physical symptoms and interpersonal difficulties with others. They also took into account such factors as gender, ethnic background, educational standing and use of antidepressant medications. After reviewing their findings, the study\u2019s authors concluded that the highest overall level of depression symptoms occurs in people classified as young adults (i.e., adults under the age of 40). Between the ages of 40 and 65, overall depression levels drop; however, a second increase in depression-related symptoms appears in older individuals over 65. When they looked at the three subsets of depression symptoms, the authors concluded that depressed mood, physical symptoms and interpersonal difficulties also rise in frequency during young adulthood, decrease during middle age and rise again in old age. Generally speaking, young adult women develop more symptoms of depression than young adult men. However, this gender gap essentially closes by the time men and women reach middle age.\r\nConsiderations\r\nA number of factors may help explain the spike in depression symptoms that occurs in elderly individuals. According to the U.S. National Library of Medicine, changing life circumstances that can boost the elderly depression rate include the death of a spouse or elderly peers, a decline in mobility or independence, the transition from a private residence to a managed care facility, and the onset of chronic health problems. Examples of health problems commonly linked to depression in elderly populations include cancer, Alzheimer\u2019s disease or other forms of dementia, various forms of cardiovascular disease, thyroid gland dysfunction, strokes and Parkinson\u2019s disease. The authors of the study in JAMA Psychiatry took the known factors for elderly depression into account when making their assessments. They concluded that these factors explain some of the rise in depression symptoms, but not all of it. In young people just entering adult life, depression symptoms are often related to diagnosable cases of depressive disorders. However, the Mayo Clinic notes, they may also be related to the onset of an adjustment disorder. Mental health professionals use this term to refer to significant problems related to the need to adapt to the effects of short-term, stressful life circumstances.