Anxiety or Depression: How to Tell Them Apart and Why It Matters

Feelings of anxiety or low mood are familiar to everyone. However, when these states become chronic and begin to interfere with daily life, it may be a matter of clinical disorders—anxiety or depression. At first glance, their symptoms may seem similar, making accurate diagnosis difficult. Nevertheless, understanding the differences between them is crucial for choosing the right treatment and improving quality of life.

Anxiety and Depression: What Are the Similarities and Differences?

Anxiety disorders and depression are often viewed as separate diagnostic categories, but in practice, their boundaries can be blurred [3, 8]. Many patients suffering from depression also experience anxiety, and vice versa [8]. This phenomenon, known as comorbidity, occurs more frequently than one might expect based on their individual prevalence [8].

Some forms, such as panic disorder and major depressive disorder, appear quite distinct. Panic disorder is characterized by sudden attacks of intense fear, accompanied by physical symptoms such as a racing heart and shortness of breath. Major depressive disorder, in turn, manifests as a persistent decrease in mood, loss of interest in activities, and other symptoms affecting sleep, appetite, and energy.

However, other forms, such as generalized anxiety disorder (GAD) and chronic depression (dysthymia), may lie on a continuum and intertwine with each other [3]. GAD manifests as constant and excessive worry about various events or activities, whereas dysthymia is a chronic, but less severe, decrease in mood that lasts for years. In such cases, symptoms can be so intertwined that determining the dominant disorder becomes extremely difficult.

Why Is It So Hard to Draw the Line? The Phenomenon of Comorbidity

The main difficulty in distinguishing between anxiety and depression lies in their high comorbidity, meaning the simultaneous presence in the same person [3, 5, 8]. Studies show that the co-occurrence of anxiety and depression is associated with a more severe disease course, chronicity, and reduced treatment efficacy [3, 5]. This may also be related to an increased familial predisposition to both disorders [3].

So-called "anxious depression" is particularly common—a syndrome in which depression is accompanied by pronounced anxiety [5]. According to DSM-5 (Diagnostic and Statistical Manual of Mental Disorders) criteria, this condition may be designated as "major depressive disorder with anxious distress" [5]. Patients with anxious depression demonstrate distinctive neurobiological profiles, including differences in hypothalamic-pituitary-adrenal (HPA) axis functioning, structural and functional brain changes, and inflammatory markers compared to depression without anxiety [5].

Such patients are more commonly encountered in primary care settings, among unmarried women, the unemployed, and less educated individuals, and they experience more severe depressive episodes [5]. Even if symptoms do not reach the full diagnostic threshold according to DSM-III-R criteria (a previous version of the manual), mixed anxiety-depressive disorder can cause significant distress and impairment in functioning [3].

Prevalence and Risk Factors

Anxiety and depression are widespread conditions and frequently accompany other diseases:

• Neurological disorders: Patients with Parkinson's disease without dementia show significantly higher levels of acute anxiety, acute stress, and depression compared to healthy individuals [1]. In Parkinson's disease with dementia, these levels are even higher [1].
• Gastrointestinal diseases: A study showed that anxiety was identified in 41.9% of patients with inflammatory bowel disease (IBD), and depression in 38.3% [2]. These rates are also high in patients with peptic ulcer disease [2].
• Thyroid disorders: A prospective cohort study involving nearly 350,000 people showed a significant link between depression, anxiety, and an increased risk of developing both hypothyroidism and hyperthyroidism [4].
• Cardiovascular diseases: Depressive and anxiety disorders are associated with an increased risk of developing cardiovascular diseases. The interaction between these conditions is multifactorial and bidirectional, highlighting the need for early assessment and intervention [6].
• Genetic factors: Genetic predisposition can contribute to the development of affective disorders such as anxiety and depression [7]. Although specific genetic markers are not yet fully understood, studies have identified polymorphisms in the FMR1 gene, as well as dopaminergic and serotonergic genes, which may be associated with these conditions [7].

Diagnosis: Tools and Approaches

Accurate diagnosis of anxiety disorders and depression requires a comprehensive approach and professional evaluation. Self-diagnosis or self-treatment can be ineffective and even dangerous.

In clinical practice, standardized questionnaires and scales are used to assess symptom severity:

• The Hamilton Anxiety Rating Scale (HAM-A) and the Hamilton Depression Rating Scale (HAM-D) are frequently used to quantify anxiety and depression, respectively [2].
• The Patient Health Questionnaire-4 (PHQ-4) is used for self-assessment of anxiety and depression symptoms, for example, in large cohort studies [4].

In addition to questionnaires, a psychiatrist or psychotherapist conducts a thorough clinical interview, collects medical history, assesses the patient's functional status, and rules out other medical causes for the symptoms. It is important to consider that even sub-syndromal forms of mixed anxiety-depressive disorder that do not meet all DSM criteria can cause significant suffering and require attention [3].

The Importance of Accurate Diagnosis and Treatment

Properly distinguishing between anxiety and depression, as well as identifying their comorbidity, is critical for selecting the most effective treatment strategy. Because anxious depression has its own unique neurobiological features, treatment approaches may differ from those for "pure" depression or anxiety [5].

Inaccurate diagnosis can lead to inadequate treatment, which in turn increases disease chronicity, reduces quality of life, and raises the risk of developing comorbid physical illnesses [3, 6]. Early and accurate assessment, diagnosis, and intervention are essential to improve prognosis and prevent long-term complications [6]. Modern treatment approaches may include psychotherapy (e.g., cognitive behavioral therapy), pharmacotherapy (antidepressants, anxiolytics), or a combination thereof, tailored individually to each patient taking into account all features of their condition.

Sources

1. Is dementia in Parkinson's disease related to chronic stress, anxiety, and depression?
2. Anxiety, depression, and personality types in patients with inflammatory bowel disease: Comparisons with peptic ulcer disease and the general population.
3. Anxiety and depression: Separate diagnostic entities?
4. Association between depression, anxiety, and thyroid diseases: A prospective cohort study of the UK Biobank.
5. Comorbid anxiety and depression: Clinical and conceptual considerations and transdiagnostic treatment.
6. Healthy mind versus healthy heart.
7. Are there genetic markers and mutations for depression and anxiety? A systematic review.
8. The blurred boundary between anxiety and depression: Fluctuations regarding comorbidity, thresholds, and hierarchy.

The information in this article is for reference purposes only and does not replace professional medical advice. Always consult a qualified specialist for diagnosis and treatment.