Clinical depression is a mental health condition where a person feels persistently sad or interest in activities they once enjoyed. Similarly, anxiety disorder is a mental health condition where a person feels very worried, nervous, or fearful about everyday situations on a regular basis for extended period of time.
Depression and anxiety are common worldwide. About 29% of people will experience depression at some point in their lives, and 30% will experience an anxiety disorder. These conditions are more often diagnosed in women than in men.
Depression and anxiety often occur together. About 60% of people with depression also have an anxiety disorder, and vice-versa. When these conditions occur together, they can make each other worse, leading to more severe symptoms and a harder time recovering. This overlap is partly due to shared genetic and biological factors, such as problems with the brain’s stress response system.
What happens in the brain
In depression and anxiety disorders, specific biological changes occur in the brain that affect how a person feels joy and reacts to different situations. In depression, a chemical in the brain called dopamine which is responsible for transmitting pleasurable sensations is reduced in areas that process reward and motivation.
This includes reduced activity in areas that control mood and emotions, such as the prefrontal cortex and the hippocampus. The hippocampus, which is important for memory and learning, tends to be smaller in people with depression. Additionally, there is often less activity in the nucleus accumbens, a region involved in reward and pleasure.
In anxiety, the brain shows increased activity in areas that process fear and threat, such as the amygdala. The amygdala is more active in people with anxiety, which makes them more sensitive to potential dangers. There is also increased activity in other regions involved in processing emotions and stress.
When depression and anxiety occur together, these brain changes can overlap. For example, both conditions can involve changes in the amygdala and prefrontal cortex, though the patterns of activity can differ.
Risk Factors
Risk factors for depression and anxiety include a combination of genetic, environmental, and lifestyle factors.
Genetic: Both depression and anxiety have a genetic component. Variations in multiple genes, such as those responsible for making dopamine and serotonin neurotransmitters each contributing a small effect, can increase the risk of developing these conditions. Genetic susceptibility is often measured using polygenic risk scores (PRS), which aggregate the effects of many genetic variants.
Environmental: Early-life adversities such as childhood abuse, neglect, and exposure to parental mental illness significantly increase the risk of both depression and anxiety. Traumatic experiences, including physical and sexual abuse, are particularly potent risk factors. Stressful life events, such as the death of a loved one, divorce, or job loss, also contribute to the onset of these disorders. Lower socioeconomic status, including factors like unemployment and financial stress, is associated with higher rates of depression and anxiety. Socioeconomic disparities can also amplify the effects of genetic susceptibility. Chronic illnesses such as cancer, thyroid disease, and chronic pain are also linked to higher rates of depression and anxiety. The stress of managing a long-term illness can contribute to mental health issues. Importantly, low self-esteem, and repetitive negative thinking are significant psychological risk factors. These traits can predispose individuals to both conditions and affect their course and severity.
Lifestyle: Substance abuse, including alcohol and drug use, is a well-documented risk factor. These substances can alter brain chemistry and exacerbate symptoms of depression and anxiety. Chronic use can lead to dependency, further complicating mental health.
Symptoms of Depression and Anxiety
Depression and anxiety manifest through a range of symptoms that can be observed by others and experienced personally by the individual.
Depression often presents with visible signs such as a persistently sad or low mood, reduced interest in activities, and noticeable changes in appetite or weight. Others may observe the person appearing fatigued, moving or speaking more slowly, or showing signs of agitation. Social withdrawal and a lack of engagement in previously enjoyed activities are also common. Internally, individuals with depression may experience feelings of hopelessness, worthlessness, and excessive guilt. They often struggle with concentration, decision-making, and may have recurrent thoughts of death or suicide.
Anxiety can be seen in behaviors such as restlessness, fidgeting, and an inability to relax. People with anxiety might appear tense, have difficulty maintaining eye contact, and exhibit nervous habits like nail-biting or pacing. They may also seem easily startled or hypervigilant. Internally, individuals with anxiety experience excessive worry, fear, and a sense of impending doom. They often report physical symptoms such as a racing heart, sweating, trembling, and gastrointestinal issues. Difficulty concentrating and sleep disturbances are also common.
Both conditions tend to last for extended periods of time and can significantly impair daily functioning and quality of life.
How does a provider diagnose it
To diagnose depression and anxiety, healthcare providers follow a systematic approach that includes clinical interviews, validated screening tools, and sometimes additional tests to rule out other conditions.
Clinical Interviews: Providers begin with a thorough clinical interview to gather a detailed history of the patient’s symptoms, duration, and impact on daily functioning. This includes asking about mood, sleep patterns, appetite, energy levels, concentration, and any thoughts of self-harm or suicide for depression. For anxiety, questions focus on excessive worry, fear, physical symptoms like palpitations, and avoidance behaviors.
Screening Tools: Validated screening tools are essential for identifying and quantifying the severity of symptoms. Common tools include the Patient Health Questionnaire-9 (PHQ-9) for depression and the Generalized Anxiety Disorder-7 (GAD-7) for anxiety. These tools are quick, reliable, and can be administered in primary care settings.
Physical Examination and Lab Tests: While there are no specific lab tests for diagnosing depression or anxiety, a physical examination and basic lab tests (e.g., thyroid function tests) can help rule out medical conditions that might mimic or exacerbate psychiatric symptoms.
Providers must differentiate between depression and anxiety, as well as other psychiatric disorders. This may involve using more specialized diagnostic tools or referral to a mental health specialist.
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