Depressive syndromes in the elderly are heterogeneous and can be difficult to identify and treat. According to the DSM-5, a major depressive episode is diagnosed when either lack of interest or pleasure or depressed mood is present along with four or more of the following symptoms: insomnia or hypersomnia, psychomotor agitation or retardation, fatigue or loss of energy, significant weight loss, diminished ability to concentrate or make decisions, recurrent thoughts of death or suicidal ideation, and feelings of worthlessness or excessive or inappropriate guilt. These symptoms must be present for at least 2 weeks [1]. It is common for older patients to express their distress using somatic terms such as “sick” or “blah” rather than psychological terms such as “depressed.” Compared to younger patients, older patients are more likely have psychomotor agitation or retardation [2] and to present with depression complicated by delusions [3]. When present delusions tend to be nihilistic, somatic, or revolve around themes of persecution or betrayal.

Because the older patient may be referred to another specialist for evaluation of a related somatic complaint or difficulty, it is important to be alert to the possibility of an underlying mood disorder. Formal screening with a standardized instrument such as the Patient Health Questionnaire (PHQ-9) [4] or the Geriatric Depression Scale (GDS ) [5] may be helpful. It is also vital to supplement the history provided by the patient with information from family members or care providers. Chapter 8—Tools for Geriatric Assessment also provides information on simple screening instruments.

When depression symptoms are present in elderly patients, it is important to proceed with a thoughtful medical evaluation, even if there is a high index of suspicion of a mood disorder. Standard laboratory assessments should include a thyroid panel, a basic chemistry panel, and CBC with differential. Because symptoms of vitamin deficiency can mimic or co-occur with depression, levels of vitamin B12, vitamin D, and folate should be measured. Finally, an EKG should be obtained to rule out any contributing arrhythmia and to identify conduction system abnormalities that might affect drug selection.

Treatment of depression in the elderly should be multifaceted and comprehensive. Antidepressant medications are often indicated. The “start low, go slow” principle applies in initial dosing decisions, but older adults often require dosages comparable to those needed by younger patients. Antidepressant medications include selective serotonin reuptake inhibitors, serotonin-norepinephrine reuptake inhibitors, tricyclic compounds, monoamine oxidase inhibitors, and other agents (e.g., bupropion and trazodone); these agents differ in side effects but none has been shown to be superior to any other. Patients may require a mood stabilizer (e.g., lithium, valproate) if there has been a diagnosis of bipolar disorder or an antipsychotic (e.g., olanzapine, quetiapine, aripiprazole) if delusions or hallucinations are present. In general these medications should not be discontinued abruptly as this may precipitate withdrawal symptoms or the re-emergence of the symptoms for which the medications were being prescribed. A psychiatrist should be consulted if the clinician is unfamiliar with the use of psychoactive drugs, especially, because of their side effect profile, when prescribing monoamine oxidase inhibitors, mood stabilizers, and antipsychotics.

Psychotherapy is nearly always of benefit for patients willing to engage in it. In some instances, it may be the only acceptable treatment option available for patients who are unwilling to take or unable to tolerate medications. There are many kinds of psychotherapy (e.g., family therapy, cognitive behavioral therapy (CBT), individual and group dynamic therapy), and there is growing knowledge documenting the effectiveness of different kinds of psychotherapy for different conditions.

Faith-based interventions may be effective for religious patients [6]. Finally, electroconvulsive therapy (ECT) and transcranial magnetic stimulation may be appropriate treatment options, but are not always available and in any case require consultation with a mental health specialist. ECT is a very effective treatment for refractory depressive conditions.

The differential diagnosis of depression includes a number of psychiatric disorders. Depression tends to be a recurrent, relapsing, and remitting condition. Some individuals never achieve complete remission of symptoms and struggle with chronic depression; formerly called “dysthymia,” this is termed “persistent depressive disorder” in DSM-5. Individuals with a history of cyclic mood swings marked by depression, irritability, and/or mania may have bipolar disorder; distinguishing recurrent major depression from bipolar depression is important because treatment is different. Finally, grief reactions are common in older adults in response to losses that grow more common with aging, e.g., bereavement, loss of independence, loss of roles and productivity, loss of health. These reactions frequently include such symptoms as sadness, anxiety, social withdrawal, difficulty making decisions, sleep disturbance, and loss of appetite. While the presence of such symptoms for a period of time after loss can be normal, the persistence of these symptoms, particularly if associated with suicidal ideation or irrational self-reproach, may signal an emerging major depressive disorder for which specific treatment will be necessary.

Major depression may accompany any medical disorder and may complicate the clinical presentation as well as treatment of the medical disorder . Cardiovascular disease [7], endocrinopathies, [8] neurologic disorders (e.g., Parkinson’s disease [9]), cerebrovascular disease [10], and the degenerative major neurocognitive disorders (e.g., Alzheimer’s disease) are commonly accompanied by depressive syndromes. In some instances, a depressive syndrome may herald a new onset neurologic disorder [11]. Regardless of the co-morbidity , a depressive syndrome should always be identified and treated and should never be dismissed as simply symptomatic of the underlying systemic process.

Anxiety disorders are common among elderly patients , both as primary and as co-morbid conditions. As with depressive disorders, older patients may have difficulty identifying their symptoms as anxiety and may instead use somatic or non-specific terms. Anxiety disorders tend to be chronic conditions, waxing and waning in severity in response to life circumstances and stressors. They may not be diagnosed until late life as new stresses and losses ensue.

Anxiety disorders should be suspected when a patient presents with difficult to diagnosis and treat symptoms. DSM-5 distinguishes several specific types of anxiety disorders. Generalized anxiety disorder is characterized by excessive worry, often accompanied by tension, irritability, sleep disruption, vague gastrointestinal symptoms, fatigue, and impaired concentration. It is frequently the somatic symptoms—not complaints of anxiety—that precipitate the visit to the doctor or other health professional. Consequently, patients with generalized anxiety disorder are frequently prescribed muscle relaxants, benzodiazepines, or other hypnotics, all of which may be poorly tolerated, increasing the risk of falls, confusion, and sedation. It is common for patients with anxiety disorders to have been prescribed benzodiazepines for decades without interruption until some medical crisis results in their discontinuation, precipitating an increase in anxiety symptoms as well as symptoms of benzodiazepine withdrawal. A careful history with corroboration by family may be needed to uncover the cause of worsening anxiety symptoms in scenarios such as this.

Other anxiety disorders are less common, and most begin earlier in life. Panic disorder typically is less severe—and panic attacks less frequent—as people age, but older patients may present with episodes of severe anxiety accompanied by multiple somatic complaints, including autonomic, cardiac, pulmonary, and gastrointestinal symptoms. A senior with obsessive compulsive disorder (OCD) may present to the physician because of physical symptoms associated with specific compulsions (e.g., dermatitis due to excessive hand washing). OCD usually becomes manifest in young adulthood but may have its onset in late life, sometimes secondary to a primary neurological disorder (e.g., basal ganglia lesion) [12]. Hoarding tends to be grouped with OCD, although persons who hoard differ from those with typical OCD in that they are not distressed by their behaviors; it is usually families or neighbors who are concerned and intervene. New onset hoarding behavior late in life may signal the onset of a progressive dementing syndrome [13]. Posttraumatic stress disorder (PTSD) is a chronic condition precipitated by one or several identifiable traumatic events. While it generally begins earlier in life and tends to grow less intense with age, PTSD may produce psychosocial disability that persists into late life. Also PTSD may develop in a senior after a profoundly traumatic event such as a severe physical trauma, including major surgery, or criminal violation such as a robbery. Specific phobias (e.g., fear of heights, animals, closed-in spaces, etc.) generally begin earlier in life and may persist into late life. One particular fear—fear of falling—tends to begin in late life [14]. It typically presents after medical events, such as a stroke or a series of falls. It may cause patients to become functionally homebound and interfere with their ability to comply with advice from their physician to pursue physical therapy, exercise, or undergo recommended evaluation.

In considering the diagnosis of an anxiety disorder in an elderly patient, it is vital to ask about prior anxiety symptoms to establish whether there is, in fact, a long-standing anxiety disorder. Anxiety symptoms truly appearing for the first time in late life should prompt a thorough medical evaluation given the possibility that a primary medical condition may be a contributing factor. New onset anxiety with shortness of breath or chest pain may be due to pulmonary emboli or coronary artery disease. New onset anxiety with insomnia, weight loss, and diarrhea may be secondary to thyroid disease. Acute onset of obsessive thinking or compulsive behavior may be symptomatic of acute basal ganglia disease or a new onset progressive neurologic disease.

Treatment should be multifaceted and comprehensive. Psychotherapy, particularly cognitive behavioral therapy, is effective in older adults [15]. Simple cognitive interventions (e.g., reassuring a patient with panic attacks that the panic symptoms will remit on their own after a few minutes) can be very powerful. Pharmacotherapy is often initiated, although the use of medications to treat anxiety disorders in the elderly has not been studied extensively. Benzodiazepines are frequently prescribed and in fact many patients have taken them for many years without apparent harm. However, benzodiazepines have serious side effects, including cognitive impairment and falls, and should be used infrequently and then with the help of a mental health professional, if possible. SSRIs are the first-line pharmacological intervention, although they are not immediately effective and are not without risk. It is best to begin with small doses and increase the dosage slowly to minimize the risk of an early paradoxical exacerbation of anxiety symptoms.

Anxiety disorders often co-exist with other psychiatric disorders. Nearly one half of older patients with a major depressive disorder have a concurrent anxiety disorder [16–18]. One quarter of those patients with anxiety disorders also have a co-morbid major depressive disorder [16]. This phenomenon has clinical implications as patients with co-morbid depression and anxiety are more impaired, have a higher risk of suicide [19], take longer to get better [20, 21], and have higher rates of relapse [22]. It is also important to note the relationship between anxiety and dementia . Late onset anxiety may herald the onset of a major neurocognitive disorder, particularly among persons who are aware of their declining cognitive function [23].

Delirium is a very important syndrome that every clinician caring for older patients must master. It is discussed briefly here for convenience and is also discussed at length in the Delirium chapter. Delirium is a syndrome characterized by the sudden onset of disturbances in attention, awareness, and cognition usually caused by an acute medical condition, substance intoxication or withdrawal, exposure to toxins, some medications including over the counter agents or topical ophthalmologic agents or combinations of these factors. Psychotic symptoms (e.g., hallucinations, delusions, misperception of actual stimuli) and psychomotor abnormalities (e.g., agitation/hyperactivity or slowing/hypoactivity) are common. Disruptions of the sleep–wake cycle and emotional disturbances (e.g., apathy, emotional labiality, irritability, rumination, fear, and euphoria) may also occur.

Risk factors for delirium include advanced age (>75 years of age), baseline cognitive impairment, prior history of delirium, vision and hearing impairment, history of cerebrovascular disease, severe co-morbid illness, and substance abuse [24]. The rate of identification of delirium is only 30 % [24]. Having a high index of suspicion is necessary in high risk populations, particularly the elderly, in whom delirium is often of the easily overlooked hypoactive type [24]. Delirium is a clinical diagnosis based on history and examination. Given the difficulty in detecting delirium, the incidence in various care settings is underestimated. Delirium is present in at least 8–17 % of older patients presenting to hospital emergency departments and 40 % of nursing home residents transferred to an emergency department for evaluation [25]. Studies have documented prevalence rates of 18–35 % in general medical settings, 25 % on geriatric inpatient units, 50 % in intensive care units (ICUs), and up to 50 % in the surgical, cardiac, and orthopedic care settings [25].

The complications of delirium are significant and potentially life threatening. Delirium in the ICU is associated with an extended length of stay, the extended use of mechanical ventilation, and a two to fourfold increase in mortality [25]. The risk of death in the first 6 months following a diagnosis of delirium in the emergency room increases by 70 % [25, 26]. Patients who develop a delirium on a general medical floor or a geriatric unit have a 1.5 fold [25] increased risk of death in the year following the index hospitalization. Delirium present at the time of admission to a post-acute care setting is associated with a fivefold increase in mortality at 6 months [27]. Postoperative delirium and delirium in the ICU are also associated with persistent cognitive impairment 12 months after hospital discharge [25, 28].