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05. Memory and concentration: brain fog, forgetfulness and circulation
KINGRAY ACADEMY · ARTICLE 05
Memory and concentration: brain fog, forgetfulness and circulation
Why do we sometimes find it harder to concentrate, and what can support brain health?
Memory and concentration are influenced by attention, sleep, stress, movement, nutrition and overall health. This article explains how the heart and blood vessels relate to the brain, what may contribute to changes in memory and when to seek a professional assessment. It also distinguishes the role of nutrients from supplement promises and findings from experimental research.
01 · Memory is more than one ability
When we want to remember something, the brain has to complete several steps. Attention must first capture the information, which is then processed, stored and later recalled.In simple terms: If we do not pay attention to information, we may not store it well. Forgetting it later does not necessarily mean that memory has been damaged.
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🧠 Processing information
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💾 Storage
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🔎 Recalling a memory
Sometimes, the problem may not be memory itself. If we are tired, stressed or doing several things at once, we may not have stored the information properly in the first place.
If we check our phone during a conversation, the brain may not give new information enough attention. Later, we may experience this as “I forgot”, even though the problem arose when the information was being stored.
Brain fog: what does it mean?
Brain fog describes difficulties rather than a diagnosis in its own right. People use the term for slower thinking, difficulty concentrating, trouble finding words or a feeling that remembering new information has become harder. On its own, it does not establish reduced blood supply to the brain or dementia.
Fatigue, pain and psychological strain can make these difficulties worse. Memory and concentration problems can also occur after COVID-19. If symptoms persist or worsen, it makes sense to explore the cause with a healthcare professional rather than simply choose a supplement. [10], [11]
02 · Sleep – a foundation for the brain
Sleep is not a period when the brain simply “switches off”. Processes important for recovery, learning and information processing take place during sleep.In simple terms: The brain works during sleep too. Sleep helps it process what we experienced and learned during the day.
If we do not sleep well, early signs may include poorer concentration, slower thinking, irritability, learning difficulties or a feeling of brain fog.
Poorer concentration
Brain fog
Learning difficulties
Daytime tiredness
How am I sleeping?
03 · Stress can occupy much of our attention
Under prolonged psychological strain, the brain constantly processes tasks, problems, deadlines and worries.
A person may then feel: “My memory no longer works as it used to.”
Sometimes, however, the issue is not memory itself but overloaded attention and working memory.In simple terms: When our minds are full of worries, less attention is available for what we are doing. Working memory lets us briefly hold information and work with it.
What may help reduce mental overload?
Habits for reducing mental overload
04 · Movement matters for more than muscles
Regular physical activity is one of the basic habits supporting a healthy lifestyle and long-term brain health.
You do not have to run a marathon. Consistency and movement suited to your fitness are what matter most.
Examples of appropriate physical activity
05 · The brain needs healthy blood vessels
The brain is a metabolically active organ and needs a continuous supply of blood, oxygen and nutrients.
Factors affecting the heart, blood vessels and metabolic health are therefore also important for its long-term health.
Vascular and metabolic factors
What we do for heart and blood vessel health also matters for long-term brain care.
How does blood reach the brain?
Arteries supply the brain with blood from the heart. Small blood vessels allow the exchange of substances needed by nerve cells. A major interruption of blood flow can cause an ischaemic stroke; another type of stroke involves bleeding. Sudden neurological symptoms therefore require immediate help.
Long-term damage to blood vessels in the brain can affect attention, planning and memory. Everyday forgetfulness alone does not establish impaired blood supply. The cause needs to be assessed in the context of overall health and appropriate examinations.In simple terms: The heart and blood vessels supply the brain, but forgetfulness alone cannot tell us whether someone has a blood flow problem.
Brain blood flow and memory: more flow does not necessarily mean better performance
The question “how can I increase blood flow to the brain?” has no universal answer in the form of one exercise or product. Managing vascular risk factors, appropriate physical activity and not smoking are part of long-term brain care. Feeling forgetful is not a measurement of blood flow. [2], [3]
Cerebral small vessel disease can be associated with cognitive difficulties. However, findings need to be interpreted alongside symptoms and an examination; the condition cannot be identified from cold hands, fatigue or the appearance of a blood drop.
06 · A brain-friendly diet is more than one miracle food
The brain needs a steady energy supply and sufficient essential nutrients. However, the overall eating pattern matters more than a single “superfood” expected to solve memory problems.
Eating patterns similar to the Mediterranean or MIND diet are of particular interest and are being studied in relation to brain health.In simple terms: Researchers study the overall eating pattern. A single food is not, by itself, a solution to memory problems.
Foods in an everyday eating pattern
For brain health, a long-term eating pattern matters more than one food or one active substance.
Favourable associations observed with dietary patterns do not guarantee dementia prevention. Findings from studies of the MIND diet are mixed.
Blood sugar, tiredness after meals and concentration
Low blood glucose can cause shaking, hunger, dizziness or confusion. A severe drop can lead to seizures or loss of consciousness. The risk particularly concerns people taking insulin or certain other diabetes medicines. [12]
Sleepiness or difficulty concentrating after a meal does not, by itself, confirm hypoglycaemia. Record recurring problems together with meal times, symptoms and medicines, and discuss them with a healthcare professional. If you have diabetes, follow your agreed plan for low blood glucose. If someone is unconscious, call the emergency services (112 in the EU) and do not give food or drink by mouth.
Here, the important distinction is between a subjective energy dip and a confirmed glucose abnormality.
07 · Vitamin B12 and other nutrients
Some nutrient deficiencies can affect the nervous system and cognitive function. Vitamin B12, folate, iron and other nutrients deserve attention according to the individual’s health situation.
Vitamin B12 deficiency risk may be higher in older adults, vegans and people with certain conditions or medicines that affect its absorption.
Nutrients and authorised claims
The answer is not automatically to take high doses of every nutrient. If a deficiency is suspected, it is more sensible to establish whether it exists and decide on the next steps according to the specific situation.
💊 B vitamins
Vitamin B12 and other B vitamins have different roles. Assess any suspected deficiency according to your individual health situation.
Correcting a confirmed deficiency is different from taking a nutrient for “better memory” without a deficiency. Vitamin B12 deficiency can also cause neurological symptoms. Supplementing it cannot, however, be considered a general treatment for forgetfulness.In simple terms: Replacing a missing nutrient and taking extra amounts are different situations. More of a vitamin does not automatically mean better memory.
Which tests may help investigate worsening memory?
Assessment starts with a discussion about when difficulties began, sleep, medicines and the impact on daily life. Depending on the findings, a doctor may arrange blood tests or an assessment of cognitive function. A vitamin B12 test can identify a deficiency, but it is not a standalone “memory test”. [1], [5]
08 · Omega-3 and the brain
Omega-3 fatty acids are fats obtained from food. Two frequently mentioned forms are EPA and DHA.
DHA is a fatty acid naturally present in nervous tissue. This does not mean that an omega-3 capsule alone will automatically solve memory or concentration problems.
Examples of omega-3 sources
One substance cannot replace good sleep, regular activity, healthy blood vessels, a balanced diet and overall care for the body.
Findings about eating fish cannot automatically be applied to omega-3 capsules. Omega-3 supplements have not shown convincing benefits in the treatment of Alzheimer’s disease.In simple terms: A nutrient can be important for normal brain function without its supplement treating a memory disorder.
09 · Alcohol and mental performance
Alcohol affects the nervous system and can also influence sleep quality.
Some people only later notice a connection between evening alcohol and morning brain fog, tiredness or poorer concentration.
When exploring your concentration, pay attention to:
- sleep quality after evening alcohol,
- energy levels the following day,
- the ability to concentrate and work with information.
10 · Medicines can be a hidden factor
Some medicines may affect sleepiness, attention or perceived mental performance in some people.
If memory or concentration problems appeared after starting or changing treatment, discuss the situation with a doctor or pharmacist.
Medicines and possible effects
Do not stop medicines on your own. If you suspect they affect concentration, discuss this with a healthcare professional.
11 · Keep using your brain
The brain is an organ that responds to stimulation. Learning new things and creative activity are natural parts of caring for cognitive abilities.In simple terms: Cognitive abilities include memory, attention and thinking. Learning involves using and practising these abilities.
Novelty, appropriate challenge and consistency matter. The brain needs a reason to learn.
A new language
A musical instrument
Reading
Creative activities
Learning a language, playing an instrument or starting a new creative activity engages several brain regions at once.
12 · Social connections are part of brain health
Conversation with other people is a complex activity for the brain. We have to listen, understand meaning, respond and process emotions.
Brain care is therefore about more than diet, supplements or exercise. A fulfilling social life is also part of brain health.
We also stimulate the brain through:
- conversations with others,
- shared activities,
- learning from other people,
- new experiences.
13 · What about “memory” supplements?
Various substances are often mentioned in relation to the brain: omega-3, B vitamins, ginkgo, ginseng, bacopa, Lion’s Mane (Hericium), magnesium and others.
Each has a different mechanism, a different level of scientific evidence and potential limitations, and may not be suitable for everyone.
Nutrients and substances in relation to the brain
If the problem is caused by insufficient sleep, stress, a medicine, a nutrient deficiency or a health factor, a supplement alone may not address the underlying cause.
When assessing a study, check who was studied, which preparation and dose were used, and what was actually measured. Findings from cells, animals or a small study are not universal proof of a benefit for memory. People taking medicines also need to consider possible interactions.In simple terms: We ask: did the study involve people or only cells or animals, what was given, and what actually changed? Only then can we assess what the result means.
Nootropics, ginkgo and Lion’s Mane: what should you check?
The label “nootropic” or an advertisement promising “mental clarity” does not guarantee an effect. For ginkgo, Lion’s Mane, resveratrol or creatine, consider the specific substance, preparation, study population and measured outcome. These substances are not interchangeable solutions to brain fog.
A laboratory finding of nerve process growth or a change in a biological marker is not, on its own, evidence of improved everyday memory. When considering supplements, distinguish biological mechanisms, clinical findings and authorised health claims. None of these terms automatically means a treatment for dementia.
14 · When should you discuss forgetfulness with a doctor?
Occasionally searching for a name or misplacing keys can happen to anyone. However, a new, marked or progressive change deserves attention, particularly when it starts affecting everyday life.
Consider a professional consultation especially if a person:
- repeatedly forgets important recent events,
- gets lost in a familiar place,
- has difficulty managing activities they previously handled routinely,
- has marked problems with speech or orientation,
- or family and close contacts notice a clear change.
Sudden speech problems, weakness or paralysis on one side of the body, facial drooping, sudden confusion or sudden vision problems may indicate an acute medical problem.
For sudden speech problems, one-sided weakness, facial drooping, sudden confusion or vision problems, call 112 or your local emergency number. Do not wait for a home measurement.
15 · Frequencies, brain waves and cells
Brain waves are patterns of nerve cell electrical activity measured, for example, using EEG. Stimulus frequency in Hz expresses the number of light or sound repetitions per second. Scientists investigate whether regular stimuli can temporarily influence measured brain activity and cell behaviour. The stimulus frequency is not automatically the frequency of all brain activity.In simple terms: Hertz (Hz) means repetitions per second. A light flashing 40 times per second does not mean that the entire brain is operating at one frequency.
A notable research example is 40 Hz. In mouse models of Alzheimer’s disease, visual and auditory stimulation was associated with changes in neural activity and microglia, the brain’s immune cells. This does not yet demonstrate treatment of Alzheimer’s disease or improved memory in people. Outcomes depend on the delivery method and other conditions; pulsing in Hz is a different measurement from light wavelength in nm.
Research into 40 Hz stimulation now also includes people. A randomised, double-blind study published in 2024 enrolled 76 patients with mild to moderate Alzheimer’s disease. It investigated one hour of daily visual and auditory stimulation over six months. Some secondary measures suggested slower decline in everyday abilities and cognitive performance, as well as less loss of brain volume. However, the primary efficacy measure, MADCOMS, did not show a statistically significant difference from the control group. The study also lacked sufficient statistical power to determine efficacy conclusively. These findings are therefore encouraging but still preliminary. [13]In simple terms: Some findings looked promising, but the main efficacy assessment did not confirm a clear difference. This study alone therefore cannot establish that the procedure effectively treats Alzheimer’s disease.
Research sources: Iaccarino et al., Nature 2016; Martorell et al., Cell 2019.
Sensory stimulation with light or sound and photobiomodulation are different research approaches. Findings from one cannot automatically be applied to the other.In simple terms: Rhythmic light and sound are not the same as photobiomodulation. Evidence for one procedure does not automatically apply to the other.
Why do we sometimes find it harder to concentrate?
Are you searching for a word you know well? Do you enter a room and forget why you came in? Is it harder to focus on work, or do you feel “foggy-headed”?
Occasional forgetfulness does not necessarily mean disease. Sleep, stress, movement, nutrition, medicines, alcohol, psychological strain and overall health influence memory and concentration.
❌ What should I buy for better memory?
✅ Why has my memory or concentration changed?
🧠 If your memory seems different from before
Start with these simple questions.
Practical checklist: memory and concentration
🧠 What should you take away from this article?
Memory and concentration are not separate from the rest of the body. Several interconnected areas influence them.
Sleep
Psychological strain
Movement
Blood vessels
Nutrition
Learning
Social life
❓ Frequently asked questions about memory and concentration
How is memory related to blood circulation?
The brain needs a continuous supply of blood, oxygen and nutrients. Long-term vascular damage can affect cognitive function, but everyday forgetfulness cannot reveal the state of blood supply to the brain.
Does forgetfulness always mean Alzheimer’s disease?
No. Changes in memory may also be associated with sleep, stress, medicines, nutrient deficiencies or other health factors. A new or progressive change that affects everyday life warrants professional assessment.
Why do I forget things I know?
Sometimes, the issue is not memory itself but insufficient attention when storing information. Tiredness, stress or multitasking may contribute.
How is sleep linked to memory?
Good sleep matters for natural processes related to learning, information processing and recovery. When concentration declines, sleep quality is therefore one of the first areas worth checking.
Can stress make concentration worse?
Prolonged psychological strain may occupy much of our attention. A person may then feel their memory has worsened, even though the issue may relate mainly to overloaded attention and working memory.
Which vitamins and minerals matter for the nervous system?
Some vitamins and minerals have authorised EU health claims relating to normal nervous system functioning or psychological function. Examples include vitamin B12 and magnesium.
Does brain training help?
Learning new things, creative activities, reading, playing a musical instrument and social connections are part of an active lifestyle. Novelty, appropriate challenge and consistency matter.
Can vitamin B12 deficiency affect the nervous system?
Vitamin B12 contributes to the normal functioning of the nervous system and to normal psychological function. If deficiency is suspected, establish whether it exists and discuss the next steps according to the specific situation.
When should memory problems be discussed with a doctor?
Consider professional advice for a new, marked or progressively worsening change that starts affecting everyday life. Sudden neurological symptoms, such as speech problems, one-sided weakness, facial drooping, sudden confusion or vision problems, require immediate medical help.
What is brain fog and what does it feel like?
It describes difficulties with thinking, attention, finding words or memory. It is not a diagnosis in itself. Fatigue and psychological strain can make it worse; persistent difficulties deserve professional assessment. [10]
Can poor circulation cause forgetfulness?
Vascular damage in the brain can affect memory and other cognitive abilities. However, ordinary forgetfulness does not confirm an inadequate blood supply. The cause cannot be identified without considering symptoms and overall health. [3]
Which exercises help memory and concentration?
Regular physical activity suited to your health and learning new things are part of brain care. No single exercise is guaranteed to eliminate forgetfulness. If you have limitations or symptoms worsen after exertion, adapt your activity with professional advice. [2]
Does tiredness after a meal mean a blood sugar crash?
Not automatically. Tiredness is nonspecific, and the feeling alone does not confirm hypoglycaemia. For recurring difficulties, the timing, medicines and, where clinically appropriate, glucose measurements matter. [12]
Does vitamin B12 improve memory for everyone?
No. B12 deficiency can damage the nervous system and needs to be addressed. Taking B12 without a confirmed deficiency cannot generally be considered a way to improve memory. [5]
What is the best supplement for brain fog?
There is no universal best supplement. Choosing one without understanding the cause may divert attention from sleep, medicines, a nutrient deficiency or an illness. Supplements do not replace assessment or treatment. [6]
Can blood tests identify the cause of worsening memory?
Blood tests can help identify some causes, such as vitamin B12 deficiency. Results are assessed alongside the history, symptoms and other investigations. A blood count or microscopic observation of a blood drop does not establish a diagnosis of dementia. [5]
🧠 Memory is part of whole-body health
Sleep, stress, movement, blood vessel health, nutrition, medicines, mental activity and social life can influence how we concentrate and work with information during the day.
📚 Sources and scientific literature
Scientific sources – expand
- [1] NIA – memory problems, forgetfulness and ageing
- [2] NIA – cognitive health, lifestyle and vascular risk factors
- [3] NHLBI – vascular damage and cognitive function
- [4] NHLBI – types and mechanisms of stroke
- [5] NIH ODS – vitamin B12, deficiency and cognitive function
- [6] NCCIH – supplements and cognitive function: what the evidence says
- [7] Commission Regulation (EU) No 432/2012 – authorised health claims for nutrients
- [8] Iaccarino et al. (2016) – 40 Hz stimulation in a mouse model
- [9] Martorell et al. (2019) – visual and auditory stimulation in mouse models
- [10] UCLH NHS – brain fog and cognitive difficulties
- [11] NHS – long COVID
- [12] NIDDK – low blood glucose and its symptoms
- [13] Hajós M. et al. Safety, tolerability, and efficacy estimate of evoked gamma oscillation in mild to moderate Alzheimer’s disease. Frontiers in Neurology. 2024;15:1343588. DOI: 10.3389/fneur.2024.1343588.
Know your body.
Start with your heart.