Anxiety is a psychological and physiologic response to stress manifested in a feeling of dread or worry and associated with increased arousal. It is a biologically adaptive symptom but can graduate to a pathologic disorder if it becomes overwhelming or limits a person’s functioning. Anxiety is distinct from fear in that it is a general feeling of ongoing distress as opposed to an acute emotional response to a perceived threat; but both anxiety and fear can manifest in physiologic symptoms, such as increased heart rate, palpitations, sweating, and other symptoms of autonomic arousal. Many medical conditions can cause symptoms of anxiety, and thus, it is necessary to rule them out prior to treatment of any anxiety disorder. Possibly because the typical age of onset of anxiety disorders is quite early (11 years) [1], these disorders in the aging population tend not to be readily recognized and treated. Additionally, anxiety is commonly comorbid with depressive symptoms, with attention predominantly focused on depression, compounding the issue. It is very important for symptoms to be detected and treated as anxiety, as it was recently suggested that even mildly elevated symptoms of worry are associated with future cognitive impairment [2]. However, considerable variation exists in prevalence estimates of most anxiety disorders. More research is needed to further investigate anxiety disorders in the aging population [3].

Key anxiety disorders in older adults include the following:

Depression is both a symptom and a disorder, marked by feelings of sadness, guilt, hopelessness, and apathy. It is quite common, as evidenced by its high lifetime prevalence (16.6% according to Kessler et al. [1]). The stereotypical impression of the elderly is that they may be more prone to depression because of loneliness or difficult life changes, but depression is not a normal part of aging and is often a treatable disorder [6]. Studies show that older people are satisfied with their lives and less likely to experience depression than younger adults [7]. However, depression is still a serious problem in the elderly, with consequences both for the individual and for society [8]. It is an important public health issue that leads to increased morbidity and disability [9]. Depression can also be more difficult to diagnose in the older population because some of its symptoms can be mistaken for normal physiologic changes of aging or side effects of medicines more commonly taken in later life.

Key depressive disorders in older adults include the following:

Adjustment disorders with anxiety or depressive symptoms, commonly diagnosed by specialists following psychosocial stressors, do not meet the criteria for a major depressive episode. There is still much to be learned about the significance of these syndromes, as well as effective treatment [10]. It seems logical that adjustment disorders would be more common in later life because the risk of stressful events and loss of life become greater; however, it appears that many older persons’ expectations of major stressors and loss change, leading to a lower prevalence of adjustment disorders with aging. In addition, coping mechanisms develop over the course of a lifetime that can lower the risk of adjustment disorders. Bereavement is a diagnosis that features depressive symptoms. It is considered normal grieving when it occurs within two months of the death of a loved one.

The lifetime prevalence of any Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition (DSM–IV) [11] diagnosis across all ages is 46.4% [1]. In particular, the lifetime prevalence of anxiety and mood disorders is 28.8 and 20.8%, respectively [1]. The age of onset of anxiety disorders is much earlier (age 11 years) than that of mood disorders (age 30 years), and mood disorders have a wider range of age at onset than other classes of psychiatric disorders [1]. There has long been an association between symptoms of anxiety and depression [12], but it is still uncertain whether these are distinct entities that may co-occur or whether they are points along the same continuum. Mixed anxiety-depressive disorder (MADD) is a provisional diagnosis in the DSM–IV and International Statistical Classification of Diseases and Related Health Problems, Tenth Revision that describes co-occurring, subsyndromal anxiety, and depressive symptoms. A study done in Great Britain showed that, in patients with MADD, 47.9% had both specific depression and anxiety symptoms; and 98.9% had nonspecific somatic symptoms, fatigue, concentration problems, sleep problems, irritability, or worry [13]. Some critics of the provisional diagnosis point out that, although MADD is associated with impaired functioning, the disorder as described has low diagnostic stability over time; and its incidence may be dependent on the defining criteria [14]. However, studies have concluded that patients with the provisional diagnosis of MADD have more severe and chronic pathology than patients with depression or anxiety only, resulting in greater vulnerability [4, 15].

National. Although the prevalence of mood and anxiety disorders declines with increasing age, they are still common and require preventive considerations, as well as intervention [7]. Special considerations in the elderly include the prevalence of chronic illness and the effect that medical comorbidities have on psychiatric complaints and vice versa. According to data from the National Comorbidity Survey Replication, the 12-month prevalence rates of any mood disorder and any anxiety disorder in adults ages 55 and older were 4.9 and 11.6%, respectively. Comorbid mood and anxiety disorders have a prevalence of 2.8% in older adults. In general, rates of both mood and anxiety disorders decrease steadily with age, except in the oldest old (age 85 or older); but this age group is the least available for study [7], and selective nonresponse of the most frail is an issue in community-based studies [8]. The most common anxiety disorder in older adults is specific phobia, followed by social phobia, PTSD, GAD, panic disorder, and agoraphobia. Being married or cohabiting is protective against mood and anxiety disorders, and low education level is a risk factor for anxiety in aging. There is a significantly higher risk of anxiety in women [7, 16]. There are no significant changes in prevalence of disorders according to race or geographic location [7]. Some considerations should be kept in mind when reflecting on these data, including possible underreporting of psychiatric illness in the aging population. Potential causes of this include embarrassment associated with the stigma of mental health problems, difficulty recalling symptoms or associating those symptoms with psychological distress, and the underrepresentation of the homeless, institutionalized, and non-English-speaking older-adult populations [7].

Worldwide. Results of a study investigating the prevalence of anxiety among older adults in low- and middle-income countries were comparable to the rates in high-income countries, with the exception of China, which had a remarkably low prevalence of anxiety. This finding may be because of a cultural stigma associated with mental illness. The highest prevalence of anxiety among older adults was found in Latin America. This study confirmed that the risk factors for anxiety in older adults in the USA parallel those in the other countries surveyed. The most important factors were gender, socioeconomic status, and comorbid physical illnesses. Significant levels of comorbid depression and anxiety were reported, with more than one fifth of the anxiety disorders featuring comorbid depression in all countries surveyed [17].

Although the prevalence of diagnosable mood and anxiety disorders decreases in later life, the elderly population still often experiences subclinical symptoms of anxiety and depression [5]. According to the US Center for Disease Control’s (CDC) report, The State of Mental Health and Aging in America, 9.2% of US adults age 50 or older and 6.5% of US adults age 65 or older reported “frequent mental distress,” defined as 14 or more days of poor mental health over the past 30-day period. Current depression was reported by 7.7% of adults age 50 or older, with 15.7% reporting a lifetime diagnosis of depression [18].

The theory behind the biopsychosocial model, a concept described by Dr. George Engel in a 1977 article in Science [22], was not new at that time by any means. Physicians have a long history of incorporating patients’ background and attitudes toward disease in their diagnosis and clinical decision making. In fact, this type of holistic approach to healing dates all the way back to Hippocrates. At its heart, the biopsychosocial model implies that a person’s biologic tissue changes his/her personal history, and his/her social circumstances all contribute to illness. The notion of “treating sick people and not diseases” [23] was emphasized again and again over time. It is notable that, in Engel’s description of the model, he added the role of the healthcare system as a social factor. At the time of the published description of the model, the so-called biomedical model of disease was falling out of favor, as people suspected the powers of pharmacologic tools focused solely on altering molecules had a limited ability to cure disease. In fact, people may have been losing faith in the healthcare system itself. Emphasis in Engel’s article was placed on the interpretation of the terms sick and well, and the idea that more factors than just biology played a role in wellness, especially in the way patients viewed their own disease. However, Engel did not diminish the importance of the biomedical in his description. His training background as an internist and the passion for psychoanalysis he later developed seem to have heavily influenced his desire to link somatic illness with life situation and personal development [24].

In 2003, an article was published that presented a new conceptual model by Wayne Katon. Despite having many similarities to the biopsychosocial model, this model was updated to become more biologically focused in presenting the reciprocal cause-and-effect pattern of chronic diseases on depressive and anxiety disorders and vice versa. It was based on a number of studies showing a link between chronic disease and mental disorders. Patients with any chronic medical condition are more likely than those without to experience depression [25], and the most common reason for new onset of major depression is the diagnosis of either the patient or his or her spouse with a life-threatening illness [26]. Because of the association between mental disorders and poor physical health, psychiatric assessment becomes all the more important in the elderly population [7]. Katon investigated the link between depressive and anxiety symptoms and disorders in patients with various neurologic diseases, diabetes, heart disease, and HIV and realized that depression plays a significant role in the development of some diseases. Depression can also develop as a result of the psychological reaction to disease. There is a causative role between depression and complications related to disease. Finally, depression is known to be a side effect of many medications and treatments. Katon also pointed out that chronic medical illness has a pathophysiologic effect on brain chemistry and function [27].