Understanding the causes of depression

Your chances of developing depression are likely to be down to a combination of factors. These include genetic or psychological factors that mean someone may be more vulnerable to developing depression, as well as environmental stresses or triggers.

Here, we explore the underlying factors that could increase your chances of becoming depressed, and look at some of the triggers that are linked to depression.

What are the five causes of depression?

Research shows that there are a number of underlying factors that can make you vulnerable to developing depression.

Five of the most common causes include:

1. Existing mental health problems
2. Physical health problems
3. Personality traits and types
4. Distressing or traumatic life events
5. Major changes in your life

While certain factors like pre-existing mental health issues, personality traits, and physical health problems are often out of our control, it remains crucial to address and actively manage these factors, as they can increase the chances of developing depression. Not seeking appropriate treatment for an existing mental health condition, such as bipolar disorder or anxiety, can heighten the risk of experiencing depression. Similarly, overlooking the significance of physical health can also contribute to this risk. Personality traits such as being a perfectionist or being very self-critical can also increase vulnerability to depression as we can be too hard on ourselves, lowering our self-esteem.

Major life changes, such as getting married or having a baby, as well as traumatic life events, such as the death of a loved one, being a victim of or witnessing a crime, or being diagnosed with a serious illness, can be a major cause of depression. These events may lead to depression because they can overwhelm your ability to cope. If you don’t have enough support following these events, this can increase the chance of your low mood developing into depression.

Traumatic events can also lead people to develop a condition known as post-traumatic stress disorder (PTSD). This condition has a number of distressing symptoms, one of which is depression. Depression can also be triggered by PTSD.

As well as these common causes of depression, there are other factors that can leave someone with an increased risk of developing depression. Some of these include poor diet, exercise and sleep as well as biological factors and brain chemistry.

Biological factors of depression

The genetic element of depression is complex and not everyone who has a genetic predisposition to depression will become depressed.

Some of the biological factors and triggers that may make someone more predisposed to developing depression include:

• Gender - women are more likely to develop depression than men. The reasons why are complex and not fully understood, but it's believed they include hormonal changes during a lifetime, for example periods, pregnancies and menopause. The demands and expectations of women in the modern world can also be a trigger
• Age – although depression can affect anyone at any age, older people are more likely to struggle with depression. This could be because the brain deteriorates with age. Depression can also be a symptom or result of conditions like dementia or stroke, which are more likely to affect older people
• Genes - genetics are complex and it’s not a single gene that’s linked to depression. It’s more likely to be small effects from a combination of genes that interact with environmental factors to cause depression. Research shows that if you have a close relative (such as a parent or sibling) who struggles with depression, this makes it more likely that you'll go on to develop depression
• Brain chemistry - our brains contain chemicals known as neurotransmitters, which send messages from one part of the brain to another. Some neurotransmitters in particular (for example, serotonin and noradrenaline), appear to be linked to mood. If these neurotransmitters aren’t working properly, this can have a negative effect on a person’s mood, leading them to develop depressive symptoms

Depression triggers

Medications, alcohol and recreational drugs can trigger depression. Some prescription medications can trigger depression as one of their side effects. If you’re taking any prescription medications, it’s important that you always check the leaflet so you know what side effects to expect. If you have any concerns about this, you should speak to your GP or pharmacist.

Taking illicit drugs or drinking alcohol can also trigger depression. Alcohol and many different types of drugs are known as ‘depressants’ because they can alter the functioning of chemicals in our brain, leading to a depressed mood.

The weather has also been known to trigger depression. Some people become depressed just during the winter months – this is known as seasonal affective disorder (SAD). During winter, we’re less able to get outside and spend time in daylight, which can affect our mood. As the nights draw in and the weather becomes worse, many people find that this can trigger the symptoms of depression.