Category: Memory

A study shows that “good” or healthy fats and “bad” fats affect brain cells in different ways.

Diets rich in saturated fat and/or refined carbohydrates are linked to neurodegenerative disorders, neuroinflammation, and cognitive dysfunction.

In contrast, diets rich in polyunsaturated fats, such as omega-3 and omega-6 fatty acids, may have neuroprotective and anti-inflammatory effects.

A study shows that “good” or healthy fats and “bad” fats affect brain cells in different ways.

The research suggests that high-fat diets will reduce polyunsaturated fatty acids and increase saturated fatty acids in the hippocampus.

The hippocampus is the region of the brain critical for learning and forming new memories.

The finding may explain the connection between high-fat foods and memory impairment, especially in older people.

Moreover, the study found that omega-3 DHA (docosahexaenoic acid) has the ability to reduce the negative effects of high fat foods-induced inflammation in brain cells.

The team’s previous work demonstrated that a diet of highly processed foods triggered brain inflammation and memory loss, both of which were successfully averted with DHA supplementation.

DHA can lower inflammation by acting directly on microglia in response to issues such as traumatic brain injury, neurodegenerative disorders (including Alzheimer’s) and brain infections.

Microglia are specialised immune cells vital to brain development and the inflammatory response to injury.

Dr Ruth Barrientos, the study’s senior author, said:

“The cool thing about this paper is that for the first time, we’re really starting to tease these things apart by cell type.

Our lab and others have often looked at the whole tissue of the hippocampus to observe the brain’s memory-related response to a high-fat diet.

But we’ve been curious about which cell types are more or less affected by these saturated fatty acids, and this is our first foray into determining that.”

DHA protects cells

For this study, microglia cells from animal tissue were harvested and cultured in the laboratory.

Then, these microglia models were exposed to palmitic acid, the most common saturated fat in foods such as shortening, pork, beef, lard, palm oil, and cocoa butter.

The results revealed that palmitic acid caused changes in gene expression involved in the inflammatory response.

However, DHA treatment completely prevented or partially lowered these alterations, and so protected cells against inflammation.

Dr Michael Butler, the study’s first author, said:

“Previous work has shown that DHA is protective in the brain and that palmitic acid has been detrimental to brain cells, but this is the first time we’ve looked at how DHA can directly protect against the effects of palmitic acid in those microglia, and we see that there is a strong protective effect.

The protective effects of DHA might, in this context, be restricted to effects on gene expression related to the pro-inflammatory response as opposed to the metabolic deficits that the saturated fat also induced.”

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• A mother who eats a high-fat diet can cause life-long changes in the brain of her child.

The study was published in the journal Frontiers in Cellular Neuroscience (Butler et al., 2023).

The method was more effective than ‘free recall’, where people remember whatever they can in any order they like.

Clustered recall is the key to remembering what really happened, eyewitness research finds.

This means remembering things from one category at a time.

So, if you were trying to remember what you did last Thursday, start with the location and concentrate on that.

Next, remember everything you can about what you were doing, then what people said, and so on.

The study used the same technique to test people’s memory for a video of a woman being mugged.

Dr Craig Thorley, the study’s author, explained:

“Using this system, we prompt eyewitnesses to first remember what the people involved in the crime looked like, then the what those people did, then the environment the crime took place in.”

Better than free recall

The study was designed to help eyewitnesses remember more about crimes.

The usual method is called ‘free recall’, where people remember whatever they can, in whatever order they like.

However, the study found that clustered recall was more effective.

Dr Thorley said:

“I think it’s likely that asking people to focus on one category of information at a time, such as what the people involved looked like, focuses their memory on that category and they offer more details related to it than they otherwise would.”

This method likely works because the brain stores and recalls related information together.

Dr Thorley said:

“It’s the first study to compare CCR to free recall.

We interviewed people using both methods and found using CCR produced superior results, with the people using it remembering more correct information about the crime.

It also increased the amount of different details they remembered.”

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The study was published in the journal Memory (Thorley, 2018).

The search for a particular book takes longer when the library is larger and more complex.

People’s memories get more cluttered with age, which is why many healthy older people have certain difficulties with retrieval.

Naturally, the search for a particular book takes longer when the library is larger and more complex.

Yet, a ‘cluttered’ memory carries distinct advantages.

Indeed, whether you call it a ‘cluttered’ memory or an ‘enriched’ memory depends on the result you expect.

For a specific answer to a precise question — such as identifying the capital of Paraguay* — clutter is the enemy.

Creativity, for instance, thrives on making unexpected connections between disparate ideas.

An older mind naturally recalls a more diverse array of memories — a trait that can be highly advantageous for creative thinking.

When older people recall information to make decisions, they are more likely to remember a wider variety of circumstances.

This wealth of experience may aid decision-making.

Even learning can be easier when you have more hooks on which to hang newfound knowledge.

Memory paradox

These ideas about memory and aging come from an article published in the journal Trends in Cognitive Sciences.

The authors were inspired by a paradox at the heart of memory: why do older people struggle to remember specific personal events despite possessing greater knowledge and wisdom?

Their answer is that healthy older people (60+) encode ‘too much’ information.

Consequently, when they attempt to retrieve a memory, a flood of irrelevant and unrelated information surfaces alongside it.

Here is how they represent it visually:

It is harder for older people to suppress irrelevant information, whereas the younger mind is more likely to zoom in on what is relevant.

Harder to suppress memories with age

A wide range of research in the neuroscience of memory supports these conclusions, the study’s authors argue.

Studies consistently show that older individuals face distinct challenges when trying to suppress irrelevant data.

As a result, searching for a specific memory often triggers an influx of unrelated background information.

The study’s authors summarise this dual-edged nature of cognitive aging in the paper:

“Older adults have greater knowledge of the world but generally show poorer episodic memory performance on many laboratory-based tasks relative to young adults.

Here, we propose that this paradox can be accounted for, at least partially, by the uniquely cluttered/enriched memory
representations of older adults.

Specifically, unlike young adults, older adults’ memory representations contain target information bound to irrelevant
and/or knowledge-based details, likely formed as a function of reduced cognitive control.

With these cluttered or rich representations, older adults are more likely to activate excessive information.

This, in turn, can pose retrieval difficulties for target information (and negatively impact episodic and working memory tasks), but can also aid performance on tasks, such as creativity, decision-making, and sometimes new learning, which benefit from access to knowledge from various sources.”

Related

• Part of the function of forgetting some things is to help us remember what is important.

* For those who are suffering, the capital of Paraguay is Asunción — not, as I once heard, Uruguay.

The study was published in the journal Trends in Cognitive Sciences (Amer et al., 2022).