Though depression is prevalent across a large portion of our population, its exact effects on the brain are not yet certain. One particular question that researchers have been asking is whether depression affects an individual's memory, and if so, in what ways does this occur? In this article, we will review some recent findings regarding this topic, so read on if you're interested!
Image is courtesy of Cleveland Clinic.
Short-term Memory Loss
Several studies have drawn parallels between depression and short-term memory loss.
For instance, a 2018 study on people with depression found that memory complaints had correlations with more severe symptoms of depression.
A 2014 meta-analysis of previous research found a clear association between depression and cognitive performance. People with depression had trouble with attention and memory. They also struggled with executive function, which is responsible for skills that help people focus on tasks, pay attention, and self-monitor their behaviour.
Another 2014 study found that the effects of depression may affect memory even after treatment. This study found that people with a prior history of depression were more likely to remember negative adjectives from a list than people who had never experienced depression.
Dementia
There may also be a link between depression and dementia, but scientists have found untangling this link challenges. Sometimes caregivers and even doctors may mistake symptoms of depression, including memory loss, as dementia in older people. However, a 2010 analysis indicates that this may not be a mistake. In many cases, the cognitive impairments that some older people experience with depression could be an early warning sign of dementia. The researchers state that depression could be an early symptom of an underlying neurodegenerative condition.
Other research has found that people with depression may have a lower volume of grey matter. For instance, a 2013 paper details grey matter changes in people with depression. Grey matter volume declined in areas of the brain associated with emotion and working memory. People with dementia may also have decreased levels of grey matter. This suggests that depression and dementia might have similar structural effects on the brain, potentially causing some of the same symptoms.
Long-term studies
A 2019 study looked at data from the National Child Development Study, a long-term study of children into adulthood. It found that people who had symptoms of depression in their twenties were more likely to have poorer immediate memory and delayed memory when they reached 50. This correlation does not mean depression causes memory loss later in life, as other factors, such as individual differences, could explain this phenomenon. Scientists must do more research to understand the link between depression and dementia.
Anti-depressants
Researchers have also identified a link between antidepressants and memory loss.
Tricyclic antidepressants may increase the risk of memory problems in some people. Similarly, a 2016 analysis found that people taking selective serotonin reuptake inhibitors (SSRIs) also experienced a decline in memory function within 8 weeks of starting treatment.
More research might clarify whether this decline continues or improves after the body adjusts to the medication.
Cognitive Impairment
In the past, little or no attention was paid to cognitive disorders associated with depression (a condition sometimes termed as pseudodementia). However, recent years have seen a growing interest in these changes, not only because of their high frequency in acute-stage depression but also because they have been found to persist, as residual symptoms (in addition to affective and psychomotor ones), in many patients who respond well to antidepressant treatment.
These cognitive symptoms seem to significantly impact patients’ functioning and quality of life, as well as the risk of recurrence of depression. Therefore, over the past decade, pharmacological research in this field has focused on the development of new agents able to counteract not only depressive symptoms but also cognitive and functional ones.
In this context, novel antidepressants with multimodal activity have emerged. This review considers the different issues, in terms of disease evolution, raised by the presence of cognitive disorders associated with depression and considers, particularly from the neurologist’s perspective, the ways in which the clinical approach to cognitive symptoms, and their interpretation to diagnostic and therapeutic ends, have changed in recent years. Finally, after outlining the pharmacodynamics and pharmacokinetics of the first multimodal antidepressant, vortioxetine, it reports the main results obtained with the drug in depressed patients, also in consideration of the ever-increasing evidence on its different mechanisms of action in animal models.
References
Perini, G., Cotta Ramusino, M., Sinforiani, E., Bernini, S., Petrachi, R., & Costa, A. (2019). Cognitive impairment in depression: recent advances and novel treatments. Neuropsychiatric disease and treatment, 15, 1249–1258. https://doi.org/10.2147/NDT.S199746
Girolamo, G., Polidori, G., Morosini, P., Mazzi, F., Serra, G., Scarpino, V., Reda, V., Visonà, G., Falsirollo, F., & Rossi, A. (2005). Prevalence of common mental disorders in Italy, risk factors, health status, and utilization of health services: the ESEMeD-WMH project. Epidemiologia e psichiatria sociale, 14(4 Suppl), 1–100. https://pubmed.ncbi.nlm.nih.gov/16447815/
Article Author: Christine Sun
Article Editors: Valerie Shirobokov, Sherilyn Wen