Forgetfulness: where the problem comes from, what the studies measured and when to contact your GP

In this article you read where forgetfulness comes from, what research into sleep, stress, attention, vitamin B12 and exercise has measured, and which signals are a reason to contact your GP. That matters, because the reasons studies can point to are usually ordinary reasons you can look at this week. The brain health scan from BioProfile gives you an indication of where you stand today in this area, as one of the 11 health areas the full scan assesses. This is not a diagnosis. It is self-insight, to see where you stand today and to help you make better choices in your food and the way you live. What this scan does not do: point out a cause. Only a doctor can say what is going on.

Causes of forgetfulness: where the complaint comes from

Thuisarts.nl names these reasons for forgetting things more quickly: getting older, stress and big events in your life, a mood disorder that a doctor names, certain medicines (sleeping medicines, medicines for mood, medicines for the bladder), and the use of alcohol or drugs.⁠¹

That list is more about your days than about your brain: you notice the symptoms of forgetfulness yourself, and the reasons sit in your nights, your load and your medicine cabinet.

Sleep, the reason with the most measurements

Two meta-analyses put numbers to a lost night: a whole night awake before learning went together with weaker memory for the new material (Hedges’ g = 0.621), and a whole night awake after learning went together with weaker memory for material that had been learned earlier (g = 0.277). The authors point to low statistical power in most of these studies and to signs of publication bias.⁠²

So a lost night weakens both the taking in of something new and the holding on to what you learned yesterday.

Bad nights are common here: in 2024, more than one in four people in the Netherlands aged 12 and over reported problems with sleeping, 31% of women and 21% of men.⁠⁴

Stress and divided attention

In 113 studies with 6,216 participants, stress before or during learning went together with weaker memory for that material, and the same held for stress at the moment of recall, more strongly with emotionally charged material.⁠³

On an ordinary day that means a tense morning makes taking something in harder, and recalling it harder too.

Attention counts by the second too. In 80 young adults with an average age of 21.7 years (range 18 to 26), lapses in attention just before recall, measured with EEG alpha power and pupil diameter, went together with forgetting on that attempt, and heavier daily media multitasking went together with more lapses and more forgetting.⁠⁵

So with forgetfulness in young adults, a large part of what feels like a poor memory is attention that was somewhere else. Thuisarts points the same way: do one thing at a time, and write down what you must not forget.⁠¹ If your head feels dull rather than forgetful, then what brain fog is and where it comes from covers that side.

Getting older, vitamin B12 and the glass with your meal

Getting older is on the Thuisarts list, and vitamin B12 is the nutrient named most often with forgetfulness in older people.⁠¹ In 2 randomised studies and 6 cohort studies, B12 intake showed no association or mixed associations with thinking ability in older people, and the authors conclude that the evidence is not strong enough to base B12 recommendations on outcomes of thinking.⁠⁶

So B12 has less evidence behind it than its reputation suggests, while a low status is still worth knowing about. The recommended amount for adults is 2.8 micrograms per day, and the two groups most often low are older people, because stomach acid production falls with age, and vegans, because B12 occurs only in animal products.⁠⁷

Alcohol is on the same list from Thuisarts.⁠¹ In the Dutch Doetinchem Cohort Study, memory was measured twice with five years in between in 2,613 adults aged 43 to 70, and red wine consumption was inversely associated with memory decline (P for trend < 0.01), while other alcoholic drinks showed no association.⁠⁸ One cohort in one place is a signal for further research rather than advice to drink.

Exercise, the broadest evidence

Across 133 systematic reviews with 2,724 randomised controlled trials and 258,279 participants of all ages taken together, exercise programmes were associated with better memory scores (SMD = 0.26) and better general thinking ability (SMD = 0.42).⁠⁹

Those are small to moderate effects across an unusually large body of studies, which makes exercise the habit with the broadest evidence here. De Gezondheidsraad advises adults at least two and a half hours of moderately intensive exercise a week and children at least one hour every day.⁠¹⁰

Ordinary forgetfulness, dementia and what a scan measures

Where ordinary forgetfulness ends and dementia begins is a question for a doctor. Thuisarts gives you the moment to call: contact your GP on a working day if you think your memory is going downhill fast, if the symptoms get in the way of ordinary daily activities, if the symptoms keep getting worse, or if you think your memory problems are bigger than other people’s.⁠¹

Those four are about direction and size: which way it is going, and how much of your day the forgetting takes up.

The brain health scan asks a number of questions about the past two weeks and turns your answers into a score with the reading band it falls in. Repeat the scan in two weeks and you have two numbers instead of an impression.

A questionnaire cannot say what the cause of the forgetting is: short nights, a period of stress, a low B12 status, a medicine taken in the evening and a low mood all read the same. So the scan is not a diagnosis. It is self-insight; blood values, your medicines and an examination are the layers a doctor adds.

In summary

Forgetfulness usually has ordinary causes: getting older, stress and big events in your life, a low mood, certain medicines, alcohol or drugs.⁠¹ Sleep carries the most measurements,⁠² bad nights are common here,⁠⁴ stress acts on both the learning and the recall,⁠³ and in young adults lapses in attention explain a large part of the forgetting.⁠⁵ Vitamin B12 is thinner evidence than its reputation,⁠^6,7 red wine was the one drink in the Doetinchem cohort with a smaller decline,⁠⁸ and exercise carries the broadest evidence.⁠^9,10 Four signals send you to your GP, and a scan gives you a starting value. It is not a diagnosis.