Hippocampus Damage: Understanding the Effects and Recovery Process

Hippocampus damage can affect memory and learning-related functions. For example, brain injury survivors with hippocampus damage may struggle to recall old memories or create new ones. Fortunately, this structure of the brain has a unique ability to heal and improve overall function by creating new brain cells through a process called neurogenesis.

This article will discuss how hippocampus damage can affect many cognitive functions and the most effective ways to promote recovery. Use the links below to jump directly to any section:

• What is the function of the hippocampus?
• Neurogenesis in the hippocampus
• Signs and symptoms of hippocampus damage
• Neurological diseases associated with hippocampus damage
• How to help the brain heal

What Is the Function of the Hippocampus?

The hippocampus is a small, C-shaped structure embedded in the temporal lobe, just below the cerebral cortex. It is a part of the limbic system, which is primarily responsible for regulating emotional responses.

The hippocampus plays a vital role in many functions such as memory, learning, spatial navigation, and behavior. However, the main role of the hippocampus is consolidating and encoding memories.

These memories can be broken into various categories:

• Declarative memories are associated with facts (semantic memories) and events (episodic memories). For example, when an individual is trying to memorize a speech or recall their last birthday celebration, they are using declarative memory. 
• Spatial memories are associated with locations such as pathways and routes. For instance, when an individual is driving home without a GPS, they can visualize and recall how the route home looks through spatial memory.

The hippocampus also helps convert short-term memories into long-term memories. However, these functions can become impaired if the brain sustains hippocampus damage.

Neurogenesis in the Hippocampus

Neurogenesis, or the creation of new brain cells, occurs in the hippocampus and is one of the most important processes for recovery after brain injury. Because of its role in neurogenesis, many neuroscientists refer to the hippocampus as the “regeneration center” of the brain.

Through neurogenesis, the hippocampus is one of the very few areas in the adult brain that is capable of producing progenitor cells. These cells have the ability to transform into different types of brain cells and migrate to other parts of the brain that need replenishing. Replacing damaged nerve cells with new healthy progenitor cells can help the brain heal and restore function. Therefore, neurogenesis improves the hope for recovery after a hippocampal injury.

Signs and Symptoms of Hippocampus Damage

While memory problems may be a sign of hippocampus damage, difficulties with memory can also develop due to aging or other neurological injuries. Understanding the signs of hippocampus damage can help you differentiate it from other memory problems and prompt you to seek the necessary care.

Potential signs of hippocampus damage may include:

• Trouble recalling new and/or old memories and information
• Difficulty holding a conversation
• Misplacing items frequently
• Poor decision-making
• Asking the same questions multiple times
• Difficulty following directions
• Getting lost in familiar places
• Forgetting to take care of oneself (i.e. eating, bathing)

It’s important to speak to your doctor if you notice any new signs or symptoms. They can make a proper diagnosis and provide the appropriate treatment for your condition. While the effects of hippocampus damage may seem permanent, there is hope for recovery.

Neurological Diseases Associated with Hippocampus Damage

Though hippocampus damage most often results from a neurological injury like a traumatic brain injury, it can also occur in other neurological diseases such as Alzheimer’s disease or depression. In many cases, whether hippocampus damage is a cause or effect of other neurological diseases is still being determined. Because memory is one of the primary functions of the hippocampus, these diseases often cause difficulty with long-term and short-term memory.

Some neurological diseases in which hippocampus damage occurs include:

Anterograde Amnesia

In the 1950’s, the case of Henry Molaison (referred to as HM) impacted neuroscience and led to new discoveries about the role of the hippocampus. HM suffered from severe epilepsy, and underwent surgery to help reduce his seizures. However, during the procedure, a significant amount of his hippocampus was removed.

Removing the hippocampus caused HM to experience anterograde amnesia for the rest of his life. Individuals with anterograde amnesia cannot remember new information, such as a current conversation, but they can often recall data and events from before the injury. Though this was an extreme case, scientists soon discovered that any level of hippocampus damage can interfere with the ability to form new memories.

Alzheimer’s Disease

Alzheimer’s disease is a degenerative disease that impairs memory and other cognitive functions. Scientists believe Alzheimer’s may affect the hippocampus first, causing it to lose volume as the disease progresses. Hippocampal volume is essential for learning and memory processes, particularly declarative memory.

Epilepsy

Scientists have also found a link between epilepsy and the hippocampus. They discovered that there are a variety of cellular changes that occur during the period before the onset of recurring seizures. Some of these changes occur in the hippocampus, including inflammation, reactive gliosis (universal reaction to brain injury), and neuronal loss.

Depression

Damage to the hippocampus can also be related to depression. Individuals who experience depression or post-traumatic stress disorder (PTSD) often show reduced hippocampal volume in their brain scans. The hippocampus can also appear smaller in size during periods of depression as opposed to remission. However, scientists are uncertain whether the shrinking in size results directly from depression or is simply a contributing factor causing depression.

Psychologists have developed a theory, known as the neurogenic hypothesis, to help explain the change in hippocampal size. The hypothesis suggests that new neurons are necessary for proper mood control and antidepressant efficacy. Since the hippocampus plays a significant role in the production of new brain cells, reduced hippocampal volume could reduce new brain cell production, resulting in mood disorders such as depression.

Stress-Induced Cognitive Dysfunction

Stress can contribute to both depression and hippocampus damage. Research shows that exposure to high levels of stress can negatively affect the hippocampus and interfere with the production of new brain cells. As a result, individuals may have difficulty with memory and other cognitive functions.

Typically, neurological diseases like Alzheimer’s and anterograde amnesia occur with severe hippocampus damage. However, with mild to moderate hippocampus damage, symptoms may be less severe and can be improved with proper treatment.

How to Help the Brain Heal from Hippocampus Damage

The brain has the ability to repair and rewire itself through a process called neuroplasticity. This process allows existing neural pathways to be strengthened and new neural pathways to be created. One essential component of this process is neurogenesis, or the creation of new brain cells (discussed above), which can occur in the hippocampus.

Activating neurogenesis and promoting neuroplasticity is the best way to help the brain heal and even reverse hippocampus damage. This can be accomplished by boosting the production of brain-derived neurotrophic factor (BDNF) in your brain. 

BDNF is a protein that plays an important role in the growth, maintenance, and regeneration of new brain cells (neurons). It’s especially important in short-term and long-term memory processing, which are often affected by hippocampus damage. Essentially, BDNF serves as the fuel necessary to activate neurogenesis, promoting recovery through neuroplasticity.

Here are some of the most effective ways to increase the production of BDNF and activate neuroplasticity:

1. Exercise Regularly

Studies have shown that exercise offers many neuroprotective and cognitive benefits, especially pertaining to memory and learning processes. Aerobic exercise in particular helps boost BDNF levels and promote hippocampal function.

Another study showed that light and moderate exercise increased the size of the hippocampus and enhanced memory retention. Further research has even shown that exercise can promote neurogenesis to reverse learning deficits caused by hippocampus damage.

Staying active and exercising regularly is a great way to activate neurogenesis and improve hippocampus damage. Be sure to start with light aerobic exercises, and increase the difficulty level as you improve. A physical therapist can also provide you with exercises for brain injury recovery that are safe and suitable for you.

2. Keep Your Brain Stimulated

Keeping your brain stimulated is another way to improve hippocampus function and activate neuroplasticity. The more the brain is stimulated, the stronger neural pathways become. When a skill or experience is performed repetitively (referred to as massed practice), the brain learns to trigger the same neurons each time and form neural connections. These connections help the brain communicate with the rest of the body to function properly. Thus, stimulating the brain can help improve hippocampus damage.

One of the best ways to stimulate the brain following hippocampus damage is practicing cognitive therapy exercises. A speech-language pathologist is an expert in cognitive therapy exercises and can provide you with personalized exercises that are appropriate for you. 

To keep your brain stimulated in between your therapy sessions, you can use the CT Speech & Cognitive Therapy App, which provides access to over 100,000+ exercises you can do from the comfort of your own home. Exercises are based on your ability level and increase in difficulty as you improve. The CT app is also great for survivors of hippocampus damage because it targets cognitive functions such as listening, attention, and memory.

Additionally, fun, therapeutic activities for TBI survivors can also help keep the brain stimulated. This can include recreational activities such as:

• Puzzles
• Video Games
• Painting
• Knitting
• Gardening

Shifting focus and paying close attention to your surroundings is another great way to stimulate the brain. Focusing on specific features such as sounds, sights, and smells can help challenge your memory skills, which is essential for hippocampal recovery.

3. Maintain a Healthy, Well-Balanced Diet

Lastly, maintaining a healthy and balanced diet is essential for brain injury recovery. More specifically, there are certain foods that help promote BDNF production and enhance memory skills. This can include fatty fish such as salmon, blueberries, dark chocolate, and turmeric roots, just to name a few.

While there are many foods that are beneficial for BDNF production, there are other foods that may actually inhibit the process and decrease hippocampal function. Particularly, foods that contain saturated fats like dairy and fatty meat, or foods with processed sugar, can reduce BDNF levels. Avoiding these foods and practicing moderation can help improve hippocampal function.

However, it’s important to note that an excess or lack of certain foods can interfere with specific medications or other pre-existing health conditions like diabetes. Always consult with your doctor before making any changes to your diet to ensure it is safe for you.

Recovering from Hippocampus Damage

The hippocampus is one of the most essential structures of the brain involved in memory. When the brain sustains hippocampus damage, it can interfere with the ability to form new memories. Fortunately, the hippocampus is one of the few unique structures that can promote neurogenesis and produce new cells in the adult brain.

Neurogenesis, an essential component of neuroplasticity, is supported by the production of BDNF, which can be increased through aerobic exercises, brain-stimulating activities, and a healthy balanced diet. The more neurogenesis and neuroplasticity are activated, the higher the chances of reversing hippocampus damage and improving your memory skills.

We hope this article helped you gain a better understanding of hippocampus damage, and how to maximize your chances of recovery.