Among the benefits offered by keto, cognitive benefits seem to be the most complex. Following a ketogenic diet has been associated with both positive and negative effects on cognitive components such as cognition, memory and migraines.
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There is plenty of anecdotal evidence, mainly in the form of testimonials, that adhering to a keto diet results in improved focus and attention throughout the day, positively impacting work performance.
On the contrary, a number of people report brain fog or difficulty completing complex tasks (brain fog is frequently a complaint in the early stages of keto when the body begins to enter the state of ketosis – known as the ‘keto flue’).
So what benefits does keto really bestow on brain function?
Cognition and memory
How can diet influence cognition?
Lately a number of researchers have been exploring this question, and investigating whether dietary modulation (e.g. adherence to keto) could lead to positive benefits[1].
With an increasingly ageing population, cognitive impairment is becoming a more prevalent condition.
This can result in neurodegenerative diseases such as Alzheimer’s disease (AD) in extreme cases, and mild cognitive impairment in less severe cases.
As a result, a number of studies have investigated the effect of ketosis on cognition and memory in elderly individuals (Studies come in the form of human clinical trials as well as animal studies with mice and rats)[1].
Ketogenesis leads to improved cognition and memory in older adults
A literature review assessed the potential benefits and effectiveness of dietary-induced ketogenesis on cognition in older adults, by analysing 11 research studies conducted in older adults.
Of the 11 studies, 7 showed statistically significant improvements in cognition markers and memory[1].
These studies demonstrated improvements compared to both pre-interventional baseline results, and the control group[1]. Although there are limitations associated with these studies (e.g. participants number, differences in trial design) the initial results are promising and lay the foundation for further research.
But the question remains, how does following a keto diet improve cognition and memory in older adults?
Glucose hypo-metabolism leads to cognitive impairment
The answer relates to impaired glucose metabolism.
With age, the brain’s ability to efficiently metabolise glucose declines, resulting in something called glucose hypo-metabolism[2].
Glucose hypo-metabolism is characterised by a decrease in brain glucose consumption and could be caused by mitochondrial impairment, defects in brain glucose transport, disruption in glycolysis, or impairment in insulin functions[2].
The exact cause is not clearly defined, but glucose hypo-metabolism is often seen in elderly patients with cognitive impairment or neurodegenerative diseases[2].
In fact, patients with the APO E4 gene (associated with increased risk of AD) demonstrate altered brain glucose metabolism and mitochondrial functions[2].
Keto reduces cognitive impairment
Following a ketogenic diet can partially ameliorate cognitive impairment resulting from glucose hypo-metabolism[2].
This is because it increases the availability of ketone bodies to supply the brain with energy, thereby bypassing the inefficient glucose metabolism in the brain[2].
By switching to use of ketones, the brain has increased energy supply resulting in improved cognition.
Studies have also shown that people with obesity have increased risk of neurological deficits and cognitive impairment, which can be improved by simply supplementing with ketone supplements[3].
This data further supports the potential positive impact of ketosis on cognitive impairment, and highlights its potential neuroprotective effect.
Epilepsy
Refractory epilepsy patients require non-pharmaceutical intervention
Epilepsy is a relatively common neurological disease resulting in seizures.
Epilepsy can usually be controlled fairly well by anti-epileptic drugs, however approximately 30% of patients are classified as ‘refractory.’
This means they have been unable to sustain adequate control of seizures following treatment with two tolerated and appropriately chosen anti-epileptic drugs[4].
As a result, there is a substantial population of patients who are unable to manage their seizures with pharmaceuticals[4].
Keto effectively controls epilepsy seizures
The ketogenic diet has been studied quite extensively in epilepsy and demonstrates favourable results.
Utilising dietary modifications to control epilepsy seizures has been documented since the 1990s, with keto diet adherence demonstrating significant seizure reduction[5].
Johns Hopkins published a study in 1998, where 150 children with epilepsy were prescribed a ketogenic diet. After one year, over 90% of children demonstrated reductions in seizures, including half the cohort experiencing a 50% decrease in seizures after a year on the keto diet[6].
Since then, the ketogenic diet has been more widely studied, continuing to demonstrate its efficacy.
In 2019, a meta-analysis of 70 studies, during which patients adhered to a keto diet, demonstrated over 40% of patients experienced a >50% decrease in seizures at both 12 and 24 months after diet initiation[7].
The benefits of the keto diet are especially important for refractory epilepsy patients, as they have more limited treatment options.
The benefits are so notable that the keto diet is advocated for by numerous epilepsy charities and non-profits, including Epilepsy Action and Epilepsy Society.
The precise mechanism by which keto improves epilepsy seizures is not fully understood. It is thought that the high levels ketone bodies and polyunsaturated fatty acids play a key role[6].
You can read further about the keto diet and epilepsy, here.
Migraine
Migraines are a common condition in which the individual suffers from head pain, photophobia and occasionally visual field distortion.
Some individuals will experience migraines extremely rarely with minimal symptoms, whereas others will be more prone to frequent or severe migraines[8]. The cause of migraine is a disorder of the brain excitatory-inhibitory balance, during which excess neuronal activity results in increased activation of the neuronal pain pathway[8].
Keto can reduce the duration of migraine episodes
Keto may have a role in reducing the negative impacts of the condition, although research is still in its early days, with some conflicting results.
A recent study examining whether the ketogenic diet could reduce the frequency, severity and duration of migraines, found that the individuals on Keto experienced a shorter duration of migraine episodes[8].
Although this is promising, the study failed to show a statistically significant improvement in the frequency or severity of the migraines experienced.
Keto leads to improved cognition, epilepsy and migraines
Keto can benefit a number of brain conditions including cognition, epilepsy and migraines.
Although the exact mechanism at play are still unclear, bypassing primary glucose metabolism, and switching to energy from ketones seems to play a key role.
It is still early days, but more research is emerging which demonstrates the benefits of keto and how it could potentially lead to neuroprotective effects.
