Major depressive disorder (MDD) is a mood disorder that causes a persistent depressed, or low, mood and reduced interest in daily activities. MDD is different from normal changes in mood because it significantly impacts daily life. The signs and symptoms of depression include sleep disturbances, reduced interest in daily activities, guilt, decreased energy, difficulty concentrating, appetite changes, psychomotor changes, and suicidal ideation. MDD is more common in genetic females than genetic males and individuals with a first-degree relative with MDD have an increased risk of developing MDD during their lifetime. Although MDD can occur amongst all age groups, it is most common to have the initial episode in children, teenagers, and young adults.
Healthcare professionals may use the patient health questionnaire (PHQ-9) to assist in making the diagnosis of MDD. This questionnaire is designed to quantify symptoms of depression and monitor severity. Professionals may also use the mnemonic SIGECAPS, which outlines the symptoms associated with MDD, during the exam to assess their risk.
There are several different treatment options for MDD. This can range from a variety of medication therapies, cognitive behavioral therapy (CBT), or different types of brain stimulation therapy. For those with treatment-resistant major depressive disorder, neurostimulation may be appropriate. Electroconvulsive therapy (ECT), a type of neurostimulation, uses electric pulses to stimulate a seizure while under anesthesia. While the mechanism of action is unclear, it is a safe treatment option for those who have not responded to more traditional methods. It can also be used when depression exists alongside psychosis (e.g., delusions, hallucinations); or those who have attempted suicide and are not responding to medication. Its success rate ranges between 58% to 70%. Repetitive transcranial magnetic stimulation (RTMS) is another form of neurostimulation that uses magnetic fields to stimulate an electric current throughout the brain. Unlike ETC, RTMS does not require anesthesia. Vagal nerve stimulation is a less commonly used method, which requires a neurosurgical procedure to stimulate the vagal nerve.
Light therapy is also used for those with seasonal affective disorder, a form of depression related to how much sunlight a person is exposed to. During periods of darkness, like during winter or fall, individuals may develop symptoms of major depressive disorder that resolve as the seasons change. Thirty minutes of white light exposure per day may be recommended during these darker months.