Depression is one of the most common mental health disorders worldwide after anxiety, affecting more than 280 million people. For moderate to severe cases, antidepressants are the mainstay of treatment.

Yet, only about one-third to two-thirds of patients respond well to these medications. This raises an important question: Why does depression persist even after several courses of treatment?

To explore this, we examined whether the way people process emotions could be linked to poor treatment response.

We used a set of computer-based tests called the emotional testing battery to assess skills such as recognising facial expressions and remembering words linked to one’s own personality.

Our study involved 54 patients with depression who were not responding well to antidepressants, compared with 45 healthy individuals. All participants also completed questionnaires on depression and anxiety symptoms.

One key task asked participants to decide whether they would like or dislike overhearing others describe them with certain personality traits, such as “kind” or “rude”.

This measured how they mentally stored (encoded) positive or negative self-related words and whether they recalled them later. We also assessed their ability to recognise facial expressions from images shown on a screen.

The results revealed three important patterns:

• Negative bias in memory: Depressed patients responded to positive and negative traits at similar speeds.

In contrast, healthy individuals reacted faster to positive traits and remembered more of them later. This suggests that healthy minds naturally give more weight to positive self-descriptions, while depressed minds do not.

• Severity slows positivity: The more severe a patient’s depression, the slower they were to process positive traits.

• No difference in facial expression recognition: Both groups performed similarly in recognising facial expressions, contrary to some earlier findings.

These patterns suggest that a negative bias in memory may help explain why depression lingers in some patients despite medication.

If future research confirms this, it could pave the way for new treatments aimed at retraining the brain to focus more on positive self-related information.

By understanding not just how depression affects mood but also how it shapes memory, we may discover better ways to help patients escape its grip.

-- BERNAMA

Dr Fitri Fareez Ramli is a lecturer and researcher in pharmacology at the Department of Pharmacology, Faculty of Medicine, Universiti Kebangsaan Malaysia, specialising in neuropsychopharmacology and emotional processing in mood disorders.