The Global Health Estimates by the World Health Organization (WHO) found that around 4.3% of the world’s population was suffering from depression in 2017, and the number has been increasing continuously. Depression can affect an individual’s ability to think, make decisions and carry out daily tasks. Sometimes even getting out of bed can be a struggle. Furthermore, people suffering from depression also experience forgetfulness and find it difficult to recall details of an event. While this loss of memory is believed to be temporary, scientists are yet to find if depression affects cognition (the ability to think and make decisions) permanently.  

What are the signs of depression?

While the signs of depression may vary for each person, the most common ones include:

• Loss of interest in activities or things that gave joy earlier
• Feeling anxious, irritated, guilty, worthless, or hopeless
• Persistent tiredness
• Loss of appetite
• Fluctuation in weight 
• Difficulty in falling asleep (insomnia) or sleeping too much
• Breathing issues or pain in the head, stomach, back, and other body parts without any physical illness
• Reduced sex drive 
• Confusion and forgetfulness
• Suicidal thoughts

How does depression affect memory?

Various studies have shown the impact of depression on memory.

• A study on 98 patients found that depression reduces the ability to distinguish between two similar memories. In this study, the patients were unable to identify objects shown on the screen which were identical to the objects they had seen before. 
• Another study found that people with depressive thoughts experienced poor concentration and difficulty remembering activities performed daily, ultimately resulting in memory loss.
• Similarly, a research including more than 5000 depressed women found that those with 3 to 5 symptoms of depression were at 60% increased risk of developing memory issues and poor cognition than those with no signs of depression. It was further found that as the number of symptoms increased, the probability of cognitive impairment also increased. 

The connection between depression and grey matter 

On studying the brain activity of depressed people in 2013, Dr Ian Anderson from the University of Manchester found that people who have been diagnosed with depression or take anti-depressants have 25% less grey matter in their brain than those who don’t. Grey matter contains the highest number of nerve cells and is responsible for managing movement, memory, and emotions. He further found that the hippocampus region of the brain (responsible for memory and learning) was smaller in size in depressed people than in those without depression. A smaller hippocampal region is associated with poor recollection of memories. 

Recommended reading: How to Care for Your Mental Health and Lead a Better Life

Conclusion

While several studies have shown that depression can cause short-term loss of memory, scientists are still researching if depressive thoughts can affect one’s cognition permanently. Furthermore, mental health experts also believe that the loss of memory due to depression can either improve or worsen with the change in emotional and mental wellbeing. Therefore, people exhibiting signs of depression are advised to reach out to a mental health professional for help when needed.

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