There has been ongoing debate about whether depression can lead to changes in heart rate and cardiovascular health. Depression is a mood disorder characterized by persistent sadness, loss of interest in usual activities, and other emotional and physical symptoms. It affects over 300 million people globally and is a leading cause of disability (WHO, 2022). Researchers have found associations between depression and various cardiovascular effects like increased risk of coronary heart disease. However, the links between depression and specific measures like heart rate are more complex. This article will examine the evidence surrounding depression and low heart rate.
What is heart rate?
Heart rate, also called pulse, refers to the number of times your heart beats per minute. A normal resting adult heart rate ranges from 60 to 100 beats per minute (MedlinePlus, 2022). The heart rate changes in response to the body’s needs, increasing during physical activity and slowing during rest. The heart pumps oxygenated blood to tissues throughout the body, so heart rate corresponds to cardiac output. Bradycardia refers to an abnormally slow heart rate below 60 bpm, while tachycardia refers to an abnormally fast rate over 100 bpm (AHA, 2015). Heart rate is regulated by electrical impulses from the sinoatrial node as well as neural and hormonal factors like epinephrine.
Symptoms of depression
Depression is characterized by a persistently low or irritable mood alongside other psychological and physiological changes. Common symptoms include (NIMH, 2022):
– Sadness, emptiness, hopelessness
– Loss of interest in hobbies and activities
– Fatigue, low energy
– Slowed movements or speech
– Difficulty concentrating or making decisions
– Sleep disturbances – insomnia or excessive sleeping
– Changes in appetite and weight
– Feelings of worthlessness or guilt
– Recurrent thoughts of death or suicide
These symptoms persist for over two weeks and cause significant impairment in daily functioning. Depression can range from mild to severe. Those with severe major depression may experience psychotic symptoms like hallucinations or delusions.
Does depression directly lower heart rate?
Research into heart rate variability and depression has had mixed results. Some studies have found that depressed individuals have lower than average heart rates and reduced heart rate variability – a marker of healthy cardiac function (Kemp et al., 2010; Brunoni et al., 2013). Other studies found no significant differences in resting heart rate between depressed and non-depressed subjects (Lehofer et al., 1997; Udupa et al., 2007). A meta-analysis by Kemp et al. concluded that depression predicts lower heart rate and heart rate variability, but the overall effect size was small (Kemp et al., 2010).
There are a few potential explanations for these inconsistent findings:
– Medications – Antidepressants like SSRIs may lower heart rate as a side effect, so studies must control for medication use.
– Severity – More severe clinical depression may have a larger impact on heart rate than milder subclinical depression.
– Comorbidities – Medical conditions linked to depression like diabetes and heart disease can also directly affect heart rate.
– Lifestyle factors – Depressed subjects are more likely to have risk factors like physical inactivity, smoking, and poor sleep habits that influence heart health.
Overall, current research does not conclusively show depression itself directly causes chronically lower heart rate. However, depression may contribute indirectly by increasing other risk factors.
Indirect links between depression and heart rate
While depression may not directly decrease heart rate, it can negatively impact cardiovascular health through various indirect pathways:
Inactivity
– Depression often leads to reduced physical activity and exercise, partly due to motivational and pleasure deficits (Knapen et al., 2015).
– Lack of activity can slow heart rate recovery after exercise and lower cardiorespiratory fitness (Knapen et al., 2015).
– Sedentary behavior also increases risks of obesity, diabetes, high blood pressure – factors associated with lower heart rate variability and higher mortality (Knapen et al., 2015).
Poor sleep
– Disturbed sleep is a diagnostic symptom of major depression, manifesting as insomnia, hypersomnia, or restless sleep (Watson et al., 2011).
– Short and disrupted sleep can activate the sympathetic nervous system, increasing blood pressure and resting heart rate (Watson et al., 2011).
– Depression-related sleep changes like loss of deep slow wave sleep may dysregulate the cardiac autonomic system and circadian rhythms (Watson et al., 2011).
Smoking
– Depression is associated with a higher incidence of smoking and lower smoking cessation rates compared to the general population (Fluharty et al., 2017).
– Cigarette smoking can raise resting heart rate by an average of 7-11 beats per minute compared to nonsmokers (Green & Srinivasan, 1978; Wilhelmsen et al., 1973).
– Smoking also increases the risk of cardiovascular diseases like coronary artery disease, a common cause of lower heart rate (Fluharty et al., 2017).
Medications
– Antidepressants, especially tricyclics, may lower heart rate by blocking cholinergic receptors that mediate parasympathetic effects (Lahmeyer & Bellur, 1987; Glassman, 2007).
– Other psychiatric medications used concurrently with antidepressants can also decrease heart rate, like benzodiazepines and atypical antipsychotics (Vieweg et al., 2013).
Comorbidities
– Depression often co-occurs with illnesses like heart disease, diabetes, and autoimmune disorders that directly affect cardiovascular function (Penninx, 2017).
– These conditions can lower heart rate by damaging electrical conduction pathways or autonomic innervation of the heart (Sgoifo et al., 2015).
– Treating the primary medical condition may resolve abnormal heart rate changes.
Can antidepressants increase heart rate?
Some types of antidepressants, particularly stimulant-based ones, may increase heart rate as a side effect. Common heart rate-elevating antidepressants include (Glassman et al., 2002; Pacher & Kecskemeti, 2004):
– Bupropion – a norepinephrine and dopamine reuptake inhibitor
– Venlafaxine – a serotonin-norepinephrine reuptake inhibitor (SNRI)
– Mirtazapine – a NaSSA antidepressant that increases norepinephrine output
– MAOIs like phenelzine and tranylcypromine – these affect norepinephrine, dopamine and serotonin
The mechanisms likely involve increased stimulation of cardiac β-adrenergic receptors by higher norepinephrine levels (Pacher & Kecskemeti, 2004). Tachycardia from bupropion may resolve within a few weeks as norepinephrine receptors desensitize (Renoir, 2013). These heart rate effects are usually mild, but patients should have close cardiovascular monitoring when starting treatment.
Lifestyle and diet changes to improve heart rate
For depressed patients concerned about potential heart rate abnormalities, certain lifestyle changes and diet modifications may help improve cardiovascular function:
– Increasing aerobic exercise – 30-60 minutes of moderate physical activity 3-5 days per week can boost heart health and endogenous endorphins to alleviate depressive symptoms (Carek et al., 2011).
– Trying stress reduction techniques like yoga, meditation, deep breathing – these stimulate the parasympathetic nervous system to decrease blood pressure and heart rate (Tyagi & Cohen, 2016).
– Following the DASH diet – its emphasis on fruits, vegetables, whole grains, lean proteins, nuts, fish, and low-fat dairy can improve cholesterol levels and blood pressure (Jackson et al., 2018).
– Managing sleep disorders – treating conditions like sleep apnea can lead to better sleep quality and normalize disrupted circadian rhythms that affect resting heart rate (Kent et al., 2018).
– Smoking cessation – quitting smoking can lower resting heart rate by 5-10 bpm on average (Green & Srinivasan, 1978).
– Medication adjustment – switching antidepressants or lowering doses, under medical supervision, may alleviate heart rate side effects.
Conclusion
In summary, the evidence is not conclusive regarding depression directly lowering heart rate. Mixed study results suggest depression has a small overall effect in reducing heart rate that may manifest only in severe clinical cases. However, depression can clearly have indirect impacts by increasing behaviors like inactivity, poor sleep, and smoking that negatively affect cardiovascular health. Treating the root causes of depression along with optimizing lifestyle factors like diet and exercise can help minimize adverse heart rate changes. Patients with significant cardiac signs should be evaluated for potential comorbidities. In some cases like with certain antidepressants, depression treatment itself may increase heart rate due to side effects. But this trend has been modestly observed and often improves over time. With proper medical monitoring, depression and its treatments do not need to disrupt normal heart rate variability.
| Study | Findings on Depression and Heart Rate |
|---|---|
| Kemp et al., 2010 | Meta-analysis found depression predicted lower heart rate and heart rate variability, but small overall effect size. |
| Lehofer et al., 1997 | Found no significant difference in resting heart rate between depressed patients and healthy controls. |
| Udupa et al., 2007 | No heart rate variability abnormalities seen in patients with mild to moderate depression. |
| Knapen et al., 2015 | Depression associated with reduced physical activity levels and cardiorespiratory fitness. |
| Watson et al., 2011 | Disturbed sleep patterns in depression can adversely affect cardiac autonomic modulation. |
