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Depressive Disorder: Diagnosis
Last reviewed: 19.10.2021
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Diagnosis of a depressive disorder is based on the identification of the symptoms and signs described above. There are a number of short questionnaires for screening. They help in establishing some depressive symptoms, but can not be used alone to establish a diagnosis. Specific closed-ended questions help in determining the patient's symptoms required by the DSM-IV criteria for the diagnosis of major depression.
The severity of the condition is determined by the degree of suffering and disruption of functioning (physical, social and professional), as well as the duration of the symptoms. The presence of suicidal risk (manifested in suicidal thoughts, plans or attempts) indicates the severity of the disorder. The doctor should gently, but directly ask the patient about his thoughts and intentions to harm himself or others. Psychosis and catatonia indicate the severity of depression. Melancholic symptoms suggest severe or moderate depression. At the same time, existing somatic problems, substance misuse, anxiety disorders can aggravate the condition.
There are no laboratory studies pathognomonic for depressive disorders. Tests for limbico-diencephalic dysfunction are rarely indicative and useful. These include the thyrotropin-releasing hormone stimulation test, the dexamethasone suppression test, the EEG during sleep to assess latent ™ rapid eye movement, which is sometimes disturbed in depressive disorders. The sensitivity of these tests is low, the specificity is somewhat better. Positron emission scan can show a decrease in cerebral glucose metabolism in the posterolateral frontal lobes and an increase in metabolism in the amygdala, the cingular gyrus, the subcranial cortex (all anxiety moderators); these changes are normalized with successful treatment.
Laboratory tests are necessary to exclude somatic conditions that can cause depression. The necessary analyzes include a general blood test, thyroid stimulating hormone levels, electrolytes, vitamin B 12, folates. Sometimes toxicological tests are necessary to exclude the use of psychoactive substances.
Depressive disorders should be distinguished from demoralization. Other mental disorders (eg, anxiety disorders) can mimic or conceal depression. Sometimes there is more than one disorder.
Major depression (unipolar disorder) should be distinguished from bipolar disorder.
In elderly patients, depression can manifest as "demented" depression (formerly called pseudodementia), it causes many symptoms and signs characteristic of dementia - psychomotor retardation and poor concentration of attention. However, dementia in the early stages can provoke the development of depression. Thus, if the diagnosis is unclear, it is necessary to treat a depressive disorder.
Differential diagnosis between chronic depressive disorders, such as dysthymia, and substance use disorders can be difficult because they can exist simultaneously and aggravate each other.
It is also necessary to exclude somatic diseases, which can cause depressive symptoms. Hypothyroidism often causes symptoms of depression and occurs frequently, especially among the elderly. Parkinson's disease can manifest with symptoms that mimic depression (ie, loss of energy, insufficient expression, low motor activity). To exclude this disorder, a thorough neurological examination is necessary.
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