Episodic memory function refers to the creation, storage and retrieval of personally experienced memories from specific places and times. These memories are crucial to carry out daily living tasks and to engage in meaningful social interactions. They are also particularly vulnerable to age-related decline. However, research has shown that some lifestyle habits can influence the rate of memory decline in late life.

Did you know?

Memory has been defined as the ability to acquire, process, store and retrieve information. It is considered essential for learning, adaptation, and survival of every living organism.¹

Memory is critical to being able to complete complex cognitive tasks, like using prior knowledge to approach new problems and drawing conclusions from existing knowledge.²

Grey matter volume and memory performance decrease with age, regardless of educational differences.³

Memory impairment has also been associated with common age-related diseases such as heart failure, diabetes or cancer.⁴ However, lifestyle factors like hydration, smoking, alcohol consumption and physical activity may also play a major role. 

The Facts

How memory works
The three main processes involved in memory are encoding, storage and retrieval (or recall).²

Encoding. Encoding is the process where information is received, understood and converted to a memory that can be stored in the brain. There are several types of encoding, the most common ones being:

• Visual encoding (converting a visual image)
• Acoustic encoding (processing sounds)
• Semantic encoding (particular meaning or context)
• Tactile encoding (processing touch, taste or smell)

Storage. Storage refers to the volume, length of time, location and method used to store information in the brain so that it can be accessed in the future. Encoded information may be stored in short-term or long-term memory.  

• Short-term memory can generally only hold seven items on average and last for only 15 to 30 seconds.
• Long-term memory, however, has virtually unlimited storage capacity and can last a lifetime.

Retrieval. Once information is stored within short- or long-term memory, individuals need to recall or retrieve it to make use of information. Short-term memory is retrieved sequentially (e.g. remembering a new phone number while you add it to your contact list), while long-term memory uses association to store and retrieve information (e.g. looking at old photos and remembering people or events from the past).

• Memories are stored and processed in different parts of the brain, in particular: the amygdala, hippocampus, cerebellum and prefrontal cortex.
• The amygdala is involved in processing emotional memories, particularly those related to fear, and in consolidating memories.
• The hippocampus plays a vital role in declarative memory (information that is retrieved and declared), episodic memory (memory of everyday events) and recognition memory (the ability to recognise that an event, object or person has been encountered before).
• The cerebellum is involved in remembering procedural memories, like playing a piano. 
  The prefrontal cortex is involved in memory used in tasks related to words and language.⁵

Lifestyle factors

• Smoking and alcohol consumption have been associated with cortical grey matter loss6, memory impairment and poorer cognition. ⁷
• Mild dehydration has also been linked to reduced short-term memory and other important aspects of cognitive function. ^{8, 9}
• Poor quality of sleep has been associated with an increased risk of dementia and cognitive decline. ¹⁰
• However, research has shown that living a physically active life, particularly engaging in aerobic training, improves cognitive function, plays a protective role against age-related cognitive decline¹² and improves memory performance and function.^11,13 

Obesity and Metabolic Syndrome¹⁴

• Episodic memory and visual working memory tend to be worse in people with obesity.15
  Higher levels of adiposity (excess body fat) are associated with lower temporal lobe volume and hippocampal volume. ¹⁶
• Obesity-related insulin resistance (where cells don't respond properly to insulin) has been found to interfere with memory performance and is related to greater reduction in grey matter volume over a 4-year period.¹⁷
• Lower haemoglobin A1c and glucose levels are associated with better scores in delayed recall, learning ability and memory consolidation. Even before experiencing symptoms of type 2 diabetes, chronically high blood glucose levels can have a negative effect on cognition, possibly due to structural changes in brain areas related to learning.¹⁸
• Obesity has been associated with higher levels of inflammation markers in the bloodstream, such as interleukin-1 (IL-1) and C-reactive-protein (CRP). Neuroinflammation, in turn, is associated with impaired episodic memory.¹⁹
• High triglyceride levels, a feature of both obesity and metabolic syndrome²⁰, damage memory by interfering with receptors in the hippocampus. However, studies on mice have shown that lowering triglycerides can reverse cognitive impairment and improve oxidative stress in the brain.²¹

Stress

• High cortisol levels, common in people with obesity or chronic stress, may influence episodic memory function. Raised glucocorticoid levels may reduce brain activity in the hippocampus, ²² while long-term elevation may reduce the size and shape of dendrites in neurons' data-id='17' data-target='#glossaryModal' data-string='Nerve cells that are the basic units of the brain and nervous system. They transmit information to other nerve cells, muscles and glands.' data-image='https://wellness-production.s3.ap-southeast-2.amazonaws.com/dWS5G3r8b6gYU7gdUa215K8c?response-content-disposition=inline%3B%20filename%3D%22Screen_Shot_2021-04-16_at_10.41.50_am.png%22%3B%20filename%2A%3DUTF-8%27%27Screen_Shot_2021-04-16_at_10.41.50_am.png&response-content-type=image%2Fpng&X-Amz-Algorithm=AWS4-HMAC-SHA256&X-Amz-Credential=AKIA33FBQTCL3JNHFS7N%2F20240419%2Fap-southeast-2%2Fs3%2Faws4_request&X-Amz-Date=20240419T144247Z&X-Amz-Expires=86400&X-Amz-SignedHeaders=host&X-Amz-Signature=d8dbf143a1f6b53650c0ed9ffe8ae30230f380bbbea6d8048ddd20b7bc00bfd2'>neurons.²³

What can we do about it

Quit smoking. Tobacco use is associated with faster brain aging, inflammation and poor memory. Avoid firsthand and secondhand tobacco smoke to preserve your brain function.

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Exercise more. A study showed that adults, of all ages, had better memory and cognitive performance after riding a stationary bike for even one 15-minute session of moderate exercise.²⁷

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Train your brain. Brain and memory training apps, like Lumosity and Elevate, are available for iPhones and Androids. A study found that young adults who played brain training games improved their brain processing speed, working memory and executive functions.²⁸

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Eat less added sugar. Eating too much sugar can impair memory. A study showed that people who drank more sugary drinks, including soft drinks and fruit juices, had poorer memories on average than those who drank less than one drink per day.²⁴

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Eat foods rich in omega-3s. A review of studies showed that when adults with mild symptoms of memory loss took omega-3 supplements rich in DHA and EPA, they experienced improved episodic memory. Omega-3s can be found in seaweed and algae, flax seeds, chia seeds, walnuts and soybeans.²⁵

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Eat berries. Berries are rich in antioxidants, such as flavonoids, and may help improve memory. One large study of over 16,000 women found that women who ate the most blueberries and strawberries slowed memory loss and cognitive decline by up to 2.5 years, when compared to those who ate the least berries.²⁶

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Maintain a healthy weight. Obesity is a risk factor for memory problems and cognitive decline. Maintaining a healthy body weight may protect you from memory issues associated with obesity.

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Get enough sleep. Sleep helps consolidate memories and convert them from short-term to long-term ones. It is recommended that adults sleep seven to nine hours per night.

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Cut down on alcohol. Memory can be affected by alcohol due to tis neurotoxic effects on the brain. Binge drinking ,in particular, can damage the hippocampus, a key area of the brain associated with memory.

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