Text adapted from: "The adult patient with an anxiety disorder," in Psychiatry in primary care by Alina R. Brotea and Richard Swinson (CAMH, 2019).
Differential Diagnosis
Specific Anxiety Disorders
Many anxiety disorders have common physical, cognitive and behavioural features. Diagnosis requires that the symptoms be considered excessive and unreasonable, and that they cause significant distress or impairment in daily functioning. Symptoms are persistent, typically lasting six months or more. Part of the challenge in diagnosis is matching the symptoms to the appropriate anxiety disorder. Anxiety disorders are differentiated from one another by the prominence of certain symptoms. Patients often have more than one anxiety disorder, so it is important to identify each one and to prioritize the one that is most distressing to help guide the treatment plan. The following section summarizes each anxiety disorder and provides helpful screening questions.
Agoraphobia
The key feature of agoraphobia is fear and avoidance of places or situations that might cause panic-like symptoms and that make the person feel trapped, helpless or embarrassed. Common places or situations include crowds, open spaces, public transportation, being alone and being in shops or theatres. In addition to experiencing panic-like symptoms, the person may also be afraid of having an embarrassing reaction (e.g., vomiting, incontinence) in these situations, even if such a reaction has never happened.
Ask the patient about:
- Fear of situations where escape may be difficult, or of developing incapacitating or embarrassing panic-like symptoms (e.g., nausea, fainting; in the elderly, fear of falling)
- Avoidance of certain places or situations, such as crowds, bridges, leaving home alone, travelling on a bus, train or highway, or needing to have a companion as a safe person. Being completely housebound is rare. It is a strongly negative prognostic factor.
Generalized Anxiety Disorder
The key feature of generalized anxiety disorder (GAD) is persistent, uncontrollable and excessive worry about a range of activities and events. Worry is associated with difficulty concentrating, insomnia, irritability, muscle tension and restlessness.
Ask the patient about:
- Excessive, uncontrollable worry about various events or activities
- A tendency to catastrophize and expect the worst in various situations
- Significant “what if” thinking (focusing on events that might possibly go wrong)
- Fatigue, restlessness, sleep disturbance, difficulty concentrating and muscle tension
- Concurrent symptoms of depression (if the above symptoms occur only when the patient feels depressed, it is more likely that the patient has a mood disorder).
Panic Disorder
Panic disorder features severe, repeated panic attacks, some of which are “out of the blue.” A panic attack is the sudden onset of intense fear that peaks within minutes and is associated with symptoms that include sweating, heart palpitations, shortness of breath, nausea, dizziness, tingling sensations and feelings of derealization. Panic attacks must be accompanied by a fear of physical symptoms and/or avoidance of the feared situations (e.g., being alone, being far from a hospital) lasting more than one month. Panic disorder is often accompanied by agoraphobia.
Ask the patient about:
- An out-of-the-blue or unexpected rush of symptoms or uncomfortable feelings such as those experienced in a panic attack (e.g., shortness of breath, diaphoresis, palpitations, shaking, paresthesia, catastrophic thinking)
- Persistent worry about having further panic attacks
- avoidance or hesitation in approaching situations expected to bring on the feared symptoms (e.g., crowds, enclosed spaces, driving, leaving home alone).
Social Anxiety Disorder (Social Phobia)
Social anxiety disorder features fear and avoidance of public performance or situations in which the person may be scrutinized by others. It may be limited to certain social interactions or it may be generalized to almost all such interactions.
Ask the patient about:
- Fear of embarrassment or negative evaluation by other people (e.g., worries about being judged on one’s intelligence, looks, speaking ability, suitability of belonging to a group)
- A history of being shy or an introvert from childhood onwards
- A history of being bullied
- Avoidance of social interactions (e.g., school events, parties, small talk with strangers, asking for directions, eating in a restaurant, asserting an opinion, job interviews, being singled out).
Specific Phobia
Phobias feature fear and avoidance of specific objects or situations to the extent that they impair the person’s functioning for a period of over six months.
Ask the patient about the fear of objects or situations such as:
- animals, snakes, insects,
- heights, storms, being near water,
- being in enclosed spaces, flying, elevators.
Anxiety Disorder Due to Another Medical Condition
Some non-psychiatric conditions can mimic or exacerbate symptoms of an anxiety disorder. These conditions can be endocrine (e.g., hyperthyroidism, diabetes), cardiac (e.g., angina), respiratory (e.g., asthma), gastrointestinal (e.g., reflux), immunological (e.g., allergies), neurological (e.g., temporal lobe epilepsy), hematological (e.g., B12 deficiency) or genitourinary (e.g., urinary tract infections). Chronic fatigue syndrome, chronic pain and terminal illness may also include anxiety symptoms. Other causal factors, such as occupational chemical exposure, should also be considered. The investigations required to rule out organic pathology depend on the patient’s clinical presentation, age, sex, health history and other individual and familial factors. A comprehensive physical exam is recommended. Canadian clinical practice guidelines (Katzman et al., 2014) outline the following considerations for baseline laboratory investigations:
- complete blood count
- fasting glucose
- fasting lipid profile (total cholesterol, very low-density lipoprotein, low-density lipoprotein, high-density lipoprotein, triglycerides)
- electrolytes
- thyroid-stimulating hormone
- liver enzymes
- urine toxicology for substance use.
Additional tests to consider include a baseline EKG and ongoing monitoring with EKG (if you are considering treatment with a medication known to carry a risk of QTc prolongation, or arrhythmia at higher doses); a pregnancy test; and 24-hour creatinine clearance, if medically indicated. If the patient is experiencing significant sleep disturbance, rule out factors such as sleep apnea. Patients on antipsychotic medication require baseline bloodwork, so consider investigating and regularly monitoring for metabolic syndrome.
Selective Mutism
Selective mutism features one month or more of failure to speak in social situations in which there is an expectation to do so (e.g., school). This failure to speak is not due to a lack of knowledge, a language barrier or another communication disorder.
Separation Anxiety
In separation anxiety, fear centres on losing or being separated from a significant attachment figure due to illness, injury, accident or kidnapping. Symptoms include avoidance behaviours such as refusing to sleep away from home or go to school, as well as physical complaints such as gastrointestinal problems, headaches and nightmares. Onset is usually in childhood, and lasts for more than four weeks; in adults, symptoms last for more than six months.
Other psychiatric disorders
Anxiety shares many symptoms with other psychiatric disorders, and comorbidity rates are high. Other psychiatric disorders to consider:
- adjustment disorder
- depression
- substance/medication-induced anxiety disorder
- personality disorders
- attention deficit/hyperactivity disorder
- body dysmorphic disorder
- eating disorders
- illness anxiety disorder
- learning disorder
- obsessive-compulsive disorder and related disorders (e.g., hoarding)
- posttraumatic stress disorder.
Adjustment Disorder
Adjustment disorder is typically triggered by a major stressor such as divorce, job termination or housing instability. It can present with symptoms of either anxiety or depressed mood, or with symptoms of mixed anxiety and depressed mood. Symptoms usually resolve within three to six months of the stressor, and do not meet diagnostic criteria for either an anxiety disorder or a mood disorder.
Depression
Depression often presents with anxiety symptoms that are new or that are an exacerbation of pre-existing anxiety conditions that only come to attention as the depression worsens. The combination of depression and severe anxiety is a concern because it increases the risk of suicidality. DSM-5 has a specifier for depressive disorders called “with anxious distress,” whose symptoms include feeling tense and restless, and fearing that something terrible is going to happen. This specifier shares many symptoms with GAD, but patients with GAD typically do not experience low mood and anhedonia, and these symptoms are not part of the diagnostic criteria.
If symptoms of anxiety occur only in the context of a mood disorder, then there is a chance that it is the mood disorder that is the primary underlying concern.
Substance/Medication-Induced Anxiety Disorder
People may seek quick relief from anxiety with commonly available substances. Anxiety can develop during or shortly after substance intoxication or withdrawal. Consider, for example, whether stopping benzodiazepine or alcohol use is responsible for the anxiety symptoms a patient is experiencing. Anxiety can also develop after exposure to certain substances. Some people use over-the-counter drugs to calm themselves. Stimulants can trigger significant anxiety symptoms and panic attacks. For example, three or four coffees, teas or caffeinated soft drinks a day can precipitate anxiety. Cocaine and amphetamines are also powerful anxiety-producing agents. Although some people report a relaxing effect while using cannabis, cannabis may cause depersonalization and panic, usually within the first few times the person uses it. The risk of psychosis also increases with cannabis use.
Personality disorders
The lifelong mood instability seen in personality disorders (e.g., borderline, histrionic and narcissistic) may present with severe anxiety symptoms at times of increased instability.