What Are the Signs of Depression? What Causes It?

asian girl feeling sad by the park

What Are the Signs of Depression? What Causes It?

Depression is one of the leading cause of disability worldwide. It is a major contributor to the world’s burden of disease. This is because a depressed person has significantly impaired daily functioning. For example, this can include difficulties maintaining relationships, performing at work or school, or to manage activities related to self-care (e.g. hygiene, physical health).

Being sad, down, or in a bad mood is part of daily life. However, depression can instead be long-lasting, more severe in intensity, and provide consequences to a person’s health. Further to that, suicidal ideation can be a symptom experienced by a person who is depressed. Close to 800,000 people die by suicide each year. This is the second leading cause of death for people within the age of 15 – 29 years old.

Signs of Depression

You may be suspecting that you are depressed. Or, you may be concerned if someone whom you care about is depressed. Please seek advice from a mental health professional if:

  • You are in a depressed mood for most of the day. This continues on for a prolonged period of time (weeks, months).
  • You notice that you lack the interest or motivation in performing daily tasks, or doing the things that you enjoy.
  • There has been significant changes to your sleep and food intake. You may be sleeping too little, or too much. There may be drastic weight loss or gain.
  • You notice yourself having difficulties concentrating or making decisions. You may feel agitated and restless.
  • There seems to be feelings of fatigue everyday, like you don’t have the energy.
  • You oftentimes feel worthless, lacking in confidence, and/ or guilty.
  • There may be suicidal thoughts, or thoughts of harming yourself.

A clinical psychologist or psychiatrist will be able to perform an assessment via a consultation, and to arrive at a diagnosis. This will assist you in selecting the most suitable therapy in addressing the concern.

What Causes Depression?

There are no single definitive cause to depression. Instead, the American Psychiatric Association defines a psychiatric disorder (such as depression) as a “result from the complex interaction of physical, psychological, and social factors“.

Here are the possible causes, broken down to the biological (physical), psychological, and social factors:


There is evidence to show a smaller hippocampus (a region of the brain) in depressed persons. A negative relationship is found between the number of depressive episodes and the size of the hippocampus.

Studies have linked the loss of volume of the hippocampus from depression as a consequence of stress. Evidence has shown changes to the structure of the hippocampus, and also the relationship of hormones secreted due to stress which impacts a person’s brain functioning.

Certain medical conditions (and its interaction with its medication) has also shown to increase a person’s risk of experiencing depression. In some, the conditions may co-occur. Among them are chronic pain, stroke, heart disease, irritable bowel syndrome (IBS), and Parkinson’s Disease (PD).


There are a variety of cognitive and behavioral processes that maintains a person’s depression. These include:


Among the environmental factors that could trigger depression are:


By recognizing the signs of depression, along with the biological, psychological, and social causes of it, implementation of an effective treatment plan is possible.

For example, a person’s hyper-responsiveness to stress can be treated through pharmacotherapy. Further to that, changes to a person’s depressive thoughts and behaviors can be effectively achieved through psychotherapy such as Cognitive-Behavioral Therapy (CBT). Lastly, informed and effective implementation of social policies can also decrease the social burden on the community’s mental health.