What is recognized as the primary symptom of obsessive-compulsive disorder (OCD)?

The primary symptom of obsessive-compulsive disorder (OCD) is characterized by recurrent, intrusive thoughts, often referred to as obsessions, alongside compulsive behaviors that individuals feel driven to perform in response to these obsessions. These obsessions typically involve persistent and unwanted thoughts that create significant anxiety or distress, leading individuals to engage in compulsive actions or rituals to alleviate the discomfort caused by these thoughts. This cycle of obsessions and compulsions is central to the diagnosis of OCD, making it essential to understand how these symptoms interact.

In contrast, the other options present symptoms that do not specifically define OCD. Inability to concentrate can occur in various mental health conditions but is not unique to OCD. Excessive worry about everyday issues is more aligned with generalized anxiety disorder, where the focus is on broader anxieties rather than specific obsessions. Severe mood swings are characteristic of mood disorders, rather than the repetitive thought and behavior patterns seen in OCD. Understanding these distinctions helps clarify why recurrent, intrusive thoughts and compulsive behaviors are identified as the hallmark of obsessive-compulsive disorder.