Forgetting part II: Error in our brain's ability to forget stuff impact mental health

The human brain is an astonishing machine, storing and managing a vast number of memories every day. This process is driven by a complex network of billions of brain cells, which work together to preserve, and retrieve information.

When we learn something new, specific neurons undergo physiological changes, creating a unique neural signature for each memory. Some of these changes are temporary, supporting short-term memory, while some neurons undergo further processing to become long-lasting memory keepers.

Together, these memory traces form a structured network called an engram. An engram allows us to recall past experiences (read more about engrams in yesterdays Part I).

While most research has focused on how we form and store memories, the mechanisms of memory retrieval and forgetting are only beginning to be understood. Shaping of what we retain and what we discard is often overlooked, yet it is crucial for healthy brain function,

Why forgetting matters
Forgetting is not a flaw in brain function but an essential component of memory management. By continuously erasing outdated or unnecessary memories, the brain optimizes its capacity to store new information and adapt to changing environments.

Memory defines who we are, shaping our experiences and guiding our decision-making. Scientists now understand that forgetting is crucial for mental health.

Imagine a mind overloaded with every detail it has ever encountered—such a scenario would make it nearly impossible to focus on relevant information.

How the brain decide what to forget
Forgetting is not a passive or failure, but an active and structured process. Some memories fade due to biological erosion, where molecular traces of an engram weaken over time. Other memories are suppressed by competing information, making them difficult to retrieve.

This occurs through multiple mechanisms, including:

• The weakening of neuron connections, making memories harder to retrieve.
• The elimination of old neurons, allowing new ones to take their place.
• The release of neurotransmitters, such as dopamine, that regulate the strength of memory traces.

These processes work together to ensure that only the most relevant and useful information is retained, optimizing cognitive function.

Not being forgetful enough causes mental health problem
While a healthy level of forgetting is beneficial, disruptions in this process can have profound psychological effects. Deficiencies in active forgetting have been linked to neurological and psychiatric disorders.

Conditions like addiction, psychosis and autism may involve impairments in memory erasure, leading to intrusive thoughts, distorted perceptions or an inability to adapt to new information.

In post traumatic stress disorder, PTSD, overwhelming recall of traumatic events lead to severe emotional and physiological responses. PTSD may involve a failure to forget distressing memories, leading to persistent emotional distress.

In these cases, unwanted memories persist, suggesting that the brain’s ability to erase or suppress certain memories is impaired.

Conversely, excessive forgetting, as seen in depression or the progressive loss of crucial memories and cognitive skills in dementia, may represent an overly active, unbalanced forgetting function.

Forgetting as a superpower
The ability to control memory strength - but apparently also the strength of efficient forgetting could revolutionize treatments for a range of cognitive and emotional disorders.

Researchers are now exploring ways to fine-tune forgetting mechanisms to help individuals suffering from memory-related disorders. Potential interventions could include therapies designed to suppress traumatic memories or enhance memory recall in those experiencing cognitive decline.

In the end, forgetting is not a weakness—it is the secret to a sharper, more focused mind. Aka, remember to forget.

About the scientific papers:

First author: Jacob A. Berry, Canada
Published in: Nature Molecular Psychiatry, September 2024
Link to paper: https://www.nature.com/articles/s41380-024-02521-9

First author: Ronald L. Davis, USA
Published in: Neuron, August 2017
Link to paper: https://www.cell.com/neuron/fulltext/S0896-6273(17)30498-1?_returnURL=https%3A%2F%2Flinkinghub.elsevier.com%2Fretrieve%2Fpii%2FS0896627317304981%3Fshowall%3Dtrue