Roughly 50 million adult Americans have hypertension.1 Chances are some of them are—or soon will be—under your care.
Hypertension is common among patients with psychiatric disorders, particularly in those with chronic mental conditions.2 Medication-associated weight gain and other reactions to psychotropics, drug-drug interactions, lack of exercise, adverse dietary habits, and pre-existing medical conditions all predispose psychiatric patients to hypertension.
Yet hypertension often goes undetected in psychiatric patients. Hypertension many times is asymptomatic—about 50% of all people with the disorder don’t even know they have it.3 Some symptoms of uncontrolled hypertension—fatigue, headache, palpitations, and dizziness—are also associated with many psychiatric disorders. As a result, psychiatrists may attempt to manage the symptoms but miss the hypertension.
Psychiatrists need to be alert for hypertension, either as a possible contributing factor to a mental disorder or as a potential side effect of a psychiatric disorder or treatment. The following diagnostic and treatment strategies will help you detect and manage this common condition.
Causes of hypertension in mental illness
The Joint National Committee on Prevention, Detection, Evaluation, and Treatment of High Blood Pressure defines elevated blood pressure as 140 mm Hg systolic and/or 90 mm Hg diastolic. The diagnosis of hypertension should be based on the average of two or more blood pressure readings at each of two or more visits after initial screening.
All patients with elevated blood pressure have an underlying physiologic abnormality that is causing their hypertension. The disorder falls within the following two categories:
- essential hypertension, emanating from an unknown cause
- secondary hypertension, resulting from an underlying, discoverable, often treatable cause.
Researchers have speculated that certain psychiatric disorders might cause, or be risk factors for, hypertension. Anxiety or panic disorders have been associated with acute (and perhaps chronic) blood pressure elevations.2 Some research suggests that patients with alexithymia are at risk for developing hypertension.4
Other studies suggest that hypertensive patients with certain psychological disorders (e.g., depression) or social factors (e.g., substance abuse) are less likely than nonaffected patients to self-report the presence of hypertension and less likely to receive medical attention for it.5
Psychiatric drugs also may affect blood pressure by one of two mechanisms:
- Pharmacodynamic—direct effects at the site of action (e.g., receptors) via physiologic mechanisms (Table 1). For example, amphetamines act directly on the sympathetic nervous system to elevate blood pressure.
- Pharmacokinetic—indirect effects on blood pressure via drug/drug interactions that alter the absorption, distribution, metabolism, or clearance of antihypertensive medications. Thiazide diuretics, angiotensin-converting enzyme (ACE) inhibitors, and salt intake restrictions can raise lithium levels. The calcium-channel blockers verapamil and diltiazem can unpredictably increase or decrease lithium levels, but the combination generally is safe. Verapamil also raises tricyclic antidepressant levels. Monoamine oxidase inhibitors (MAOIs) used in tandem with the antihypertensive reserpine can cause hypomania. Beta-blocker levels are increased when used in concert with selective serotonin reuptake inhibitors. Use of carbamazepine with calcium-channel blockers can elevate carbamazapine levels and diminish the effectiveness of the calcium-channel blocker.
Table 1
POSSIBLE PHARMACODYNAMIC EFFECTS OFPSYCHIATRIC MEDICATIONS ON BLOOD PRESSURE
| Psychiatric medication | Effect on blood pressure |
|---|---|
| Amphetamines | ▲ |
| Benzodiazepines | Withdrawal may cause ▲ |
| Tricyclic antidepressants | ▲ or ▼ (postural hypotension or supine hypertension) |
| Methylphenidate | ▲ |
| Monoamine oxidase inhibitors | ▲ may precipitate an acute hypertensive crisis, especially with foods with high tyramine content (e.g., red wines, aged cheeses) |
| Lithium | ▼ via direct effect on renal concentrating ability |
| Venlafaxine | ▲ dose-related, <1% incidence |
| Antipsychotics (both typical and atypical) | ▼ |
Symptoms, complications of high blood pressure
Symptoms that may be associated with high blood pressure include headaches, dizziness, lightheadedness, fatigue, palpitations, and chest discomfort. Patients may also experience symptoms secondary to end-organ damage (e.g., shortness of breath from congestive heart failure).
Most people, however, experience no symptoms when their blood pressure is elevated. This is one reason most people with hypertension do not adequately control their blood pressure.
Aside from the long-term end-organ damage caused by persistently elevated blood pressure, hypertension also has been found to cause psychiatric disorders, though not directly. For example, post-MI depression is well-recognized. Hypertension may also cause multi-infarct dementia with resultant depression, paranoia, or other psychotic features.
The psychological burden of having chronic and usually incurable (though controllable) hypertension may worsen depression or anxiety disorders. Patients with a chronic psychiatric illness generally have a higher incidence of chronic medical problems.
Likewise, patients with chronic medical disorders have a higher incidence of psychiatric complaints.6
Patient evaluation
When evaluating the patient with elevated blood pressure, it is important to:
- detect and confirm hypertension
- detect target-organ disease (e.g., renal damage or congestive heart failure)
- identify other cardiovascular risk factors (e.g., diabetes mellitus, hyperlipidemia, obesity)
- identify secondary causes of hypertension, such as endocrine abnormalities (e.g., hyperaldosteronism, thyroid disorders), kidney disease, obstructive sleep apnea, and response to medications.