Major depressive disorder
Major depressive disorder, or simply MDD is a mental health condition marked by a persistent feeling of sadness, and a loss of interest or pleasure in everyday activities.
These feelings don't just come and go. Typically they persist for months and interfere with work, relationships, and daily functioning.
Now, our mood mainly depends on the neurotransmitters called monoamines, including serotonin, norepinephrine, and dopamine.
These neurotransmitters talk to the limbic system to control emotions, motivation, appetite, and movement. They also reach the frontal cortex to help with attention and memory.
It's normal to feel down after a breakup or a bad day at work. Most of the times, those feelings fade in a few days and you start enjoying life again.
But MDD is different. Sadness doesn't fade, it sticks around most of the day, nearly every day, and makes it hard to feel like yourself.
In MDD the brain doesn't have enough serotonin, dopamine, or norepinephrine. That leaves the mood circuits underactive, which is why people feel down, lose interest, and have trouble thinking clearly.
Several risk factors can increase the risk of developing major depressive disorder. First, early life experiences.
For example, being bullied at school or growing up with constant criticism can leave lasting marks. Next, stressful life events, like losing a job or going through a divorce can also increase the risk.
Finally, genetics are thought to play a role, since major depressive disorder is more common in first-degree relatives. Next, let's talk about clinical manifestations.
Major depressive disorder has two core features. The first is a persistently depressed mood.
A person may feel sad, empty, or emotionally low for most of the day. Some describe a sense of hopelessness as if their future looks blank.
Others struggle with motivation, which makes basic daily activities overwhelming, like getting out of bed or maintaining personal hygiene.
Sometimes people say they're not sad, but you can tell by their face. They look tearful, withdrawn, or like they might cry at any moment.
In children and adolescents, depression doesn't always look like sadness. Instead, it often shows up as irritability.
Sometimes they may want to be left alone. Other times they feel like everyone is annoying or they become angry easily.
So with anhedonia, a person no longer enjoys things that used to make them happy. Like playing their favorite video game.
But the story does not end here. Major depressive disorder includes additional symptoms that can be divided into physical and psychological features.
Let's start with neurovegetative features. First, sleep issues.
Some individuals experience insomnia, struggling to fall asleep and lying awake for hours. Others experience hypersomnia, sleeping for long periods but still waking up tired.
Next is low energy and fatigue. Even simple tasks like dressing up for work can feel draining and take far longer than usual.
These mood changes also affect appetite. Some people lose their appetite, saying they're not hungry or that food has little or no taste.
They might describe food as eating cardboard. This often leads to weight loss.
On the flip side, some individuals turn to food for comfort, especially carbohydrates, sweets, and chocolates, which eventually results in weight gain.
Next up, we have psychomotor manifestations. In some cases, a person becomes agitated and restless, unable to sit still.
They may pace around the room, rub their fingers, wring their hands, or pull their clothes, but that's not always the case.
Some individuals experience psychomotor slowing, their movements become slow, almost as if they're walking through mud. Speech might become sluggish, with long pauses before answering questions with short one-word replies.
Now, moving on to psychological features. First, there are cognitive difficulties, such as difficulty concentrating or thinking clearly.
For example, a student might start failing exams because they cannot focus or process what they're reading. In older adults, these cognitive changes can sometimes be mistaken for early signs of dementia.
Next, there are intense feelings of guilt and worthlessness. A person may feel unworthy or even guilty when good things happen to them.
In severe cases, this guilt can become delusional, such as believing that natural disasters happen because of something they did in the past.
Lastly, some individuals experience suicidal thoughts. These might include wishing they would not wake up in the morning or believing that others would be better off without them.
In more severe cases, these thoughts can progress to planning suicide. Now, to diagnose a major depressive disorder, we need to check several key boxes.
First, the person must meet the criteria for a major depressive episode. A helpful way to remember the core features of a major depressive episode is the mnemonic sad to sigicaps.
The S stands for sadness, or persistently depressed mood. A is for anhedonia, and D2 refers to duration of symptoms which must be present for at least 2 weeks.
The remaining features are captured by ciga caps. SI stands for sleep issues, G for guilt and worthlessness, E for low energy, and C for cognitive issues.
Next, A refers to changes in appetite, P stands for psychomotor agitation or slowing, and S is for suicidal thoughts. So to diagnose a major depressive episode, the person must present with at least 5 of these 9 features, and 1 must be either depressed mood or anhedonia.
In addition, the symptoms must cause significant distress and impairment in daily functioning, including work, school, and relationships.
But that's not all. You need to rule out that the symptoms are not caused by substance use or another medical condition.
Only then can you say the person is experiencing a major depressive episode. However, a single major depressive episode alone is not enough to diagnose major depressive disorder.
We also have to make sure the symptoms aren't part of another mental condition like schizophrenia. Also, the person must have no history of manic or hypomanic episodes.
If such episodes were present, the diagnosis shifts away from major depressive disorder toward a bipolar spectrum disorder.
Once you check all these boxes, you can diagnose a major depressive disorder. However, a major depressive disorder is not a uniform condition.
Some depressive episodes follow distinct patterns called specifiers, which do not change the diagnosis but modify the presentation.
First, let's focus on MDD with melancholic features. In this type, people lose almost all pleasure in things they normally enjoy, and their mood doesn't get better even when something good happens.
This type of depression is usually very severe, and often worse in the morning, with people waking up earlier than usual.
They may move or speak very slowly, or sometimes be unusually restless. People often lose their appetite or weight and feel extreme or inappropriate guilt.
This type of depression is more common in severe cases, in hospital settings, and can sometimes include psychotic symptoms.
MDD with atypical features is characterized by mood reactivity. In other words, the person's mood can actually get a little better when something positive happens.
People with this type often sleep a lot more than usual, eat more, and gain weight. Many also feel something called leaden paralysis, which is a heavy weighted feeling in the arms or legs that can last for hours.
They're often very sensitive to being rejected or criticized, which can affect school, work, or relationships, and this sensitivity can stick around even when they aren't depressed.
Atypical features don't happen at the same time as melancholic features, and despite the name, this is actually a common type of depression.
MDD with peripartum onset starts during pregnancy or within the 1st 4 weeks after delivery. Symptoms may occur with or without psychotic features, and severe cases can include hallucinations or delusions.
Risk is higher in women with a history of mood disorders, especially bipolar disorder or prior postpartum episodes. It's important to distinguish peripartum depression from the baby blues, which are very common, short-lived, and don't interfere with daily life.
MDD with seasonal pattern is defined by recurrent depressive episodes that occur at the same time every year, usually starting in the fall or winter and improving in the spring.
It's more common in younger adults, and in places with long winter and less sunlight. Moreover, reduced sunlight increases melatonin secretion and disrupts the circadian rhythm, which affects sleep, mood, and energy levels.
This is not just being sad in winter, the pattern repeats every year, and it's not explained by everyday activities like school stress.
Finally, treatment usually combines psychotherapy, such as cognitive behavioral therapy, with antidepressants, which are medications that increase available levels of serotonin, norepinephrine, and dopamine in the brain.
The first line medications include selective serotonin reuptake inhibitors and serotonin norepinephrine reuptake inhibitors, followed by norepinephrine dopamine reuptake inhibitors and monoamine oxidase inhibitors.
Less commonly used medications include tricyclic antidepressants. Alright, as a quick recap.
To diagnose major depressive disorder, a person must meet criteria for a major depressive episode. A helpful mnemonic is sad to sigicaps.
S stands for sadness, A for anhedonia, and D2 for duration of at least 2 weeks. SIGAs include sleep issues, guilt, low energy, cognitive difficulties, appetite changes, psychomotor features, and suicidal thoughts.
At least 5 of these symptoms must be present, and 1 of them must either be sadness or anhedonia. Also, these symptoms must interfere with daily life and not be caused by substance use or another medical condition.
On top of that, the major depressive episode should not be a part of another psychiatric condition.
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