Can depression alter our memory?

What is depression?

Depression (also called "major depressive disorder") is a common psychological condition. Depression is a disorder of the neurological functioning of the brain. It manifests itself by mood disorders leading to:

• Fatigue that is not compensated by sleep,
  
• Lack of energy and slowing of movements,
  
• Deep sadness,
  
• Loss of general pleasure (no more desire to go out, see friends or engage in activities...),
  
• Emotional hypersensitivity with feelings of abandonment, loneliness and anxiety,
  
• Negative thoughts,
  
• Attention, concentration and memory problems.
  

Depression is not simply a bout of low spirits or temporary sadness. It is a real psychological illness.

Depression can be diagnosed and treated quite easily at the beginning of the illness. However, willpower alone does not cure it, as there is a so-called "paralysis of willpower" associated with psychomotor retardation.

It must therefore be treated before it becomes complicated, chronic or before it leads to complications such as the risk of suicide. In a number of cases, and in particular in cases of complex depression, a psychiatrist's help may be required.

What is the link between memory and depression?

There is a growing body of research on the direct link between memory and depression.

Experts point out the influence of the stress hormone cortisol on memory retention. Indeed, while mild and moderate levels of stress can improve memory and other cognitive functions by providing individuals with a higher degree of motivation, high levels of stress can release chemicals in the brain that lead to memory impairment.

When levels of cortisol in the brain are found to be too high, they prevent the memory core (the hippocampus - the area of the brain located in the temporal lobe) from functioning properly. And when memories cannot be properly integrated by the hippocampus, their long-term storage is altered. As a result, memories tend to fade very quickly.

In the study Cognitive impairment in depression, it is suggested that depression leads to a decline in intellectual performance in the areas of memory, attention and executive functions. Depressed patients struggle with concentrating and keeping attention more than others, even when it comes to everyday actions.

The authors of this study associate cognitive disorders related to depression with dysfunctions in the frontal lobes, "particularly in the ventromedial region and the dorsal part of the anterior cingulate cortex". These cognitive abnormalities may persist beyond the depressive episode.

Impaired cognitive function is often correlated with the intensity of the symptoms.

In addition, meta-analyses point to the existence of a deficit in processes that require effort: a depressed patient does not have enough energy to organise the information in a correct way for it to be memorised, making memory retrieval also deficient.

Depression and memory loss: what to do?

Memory loss due to depression is real. This phenomenon is called "scarring of the brain". It refers to the after-effects on the brain following a depressive episode. With each episode, and especially after the second or third episode and even more so after the age of 40, the recovery of all brain functions is 90-95% but not 100%. The more depressive episodes are repeated, the more there will be after-effects on memory and mental agility.

Nevertheless, the cognitive deficit is recoverable with cognitive therapies, exercises or self-help groups in cases of mild to moderate depression.

In cases of more severe depression, a multidisciplinary approach is necessary. Drug treatments should be combined with psychological therapies, memory exercises and even dietary supplements with magnesium and B vitamins.

Understanding and support coming from the patient's entourage is also essential.