Tired and forgetful at the same time. That combination brings many people over 60 to their GP, and rightly so. Your GP then checks a fixed set of blood values, not to find dementia, but to find causes that something can be done about.
Fatigue and forgetfulness often share the same source.
Which blood values does the GP request?
Usually six to eight. Vitamin B12 and folate, TSH for your thyroid, haemoglobin for anaemia, glucose or HbA1c for your blood sugar, sodium and calcium for your salt balance, and your kidney function. Together those cover the most common treatable causes.
| Value | What it covers | What an abnormal result may mean |
|---|---|---|
| Vitamin B12 | Nerves and blood cell production | Slowness, forgetfulness, tingling |
| Folate | Blood cell production | Fatigue, anaemia |
| TSH | How your thyroid is working | Slow thinking, feeling cold, weight gain |
| Haemoglobin | Oxygen transport in your blood | Tiredness, breathlessness, poor concentration |
| Glucose or HbA1c | Your blood sugar | Swinging energy, a foggy head |
| Sodium and calcium | Salt balance | Confusion, drowsiness, muscle complaints |
| Kidney function | Clearing waste products | Waste building up, drowsiness |
This list is not a dementia test. It is a list for ruling things out.
Why does vitamin B12 come first?
Because a deficiency is common after 60, and because it is treatable. Your stomach produces less acid over the years, so you absorb less B12 from your food. A systematic review found an association between low B12 status and cognitive decline (Clarke et al., 2012).
Stomach acid inhibitors and metformin also lower your B12. If you take either long term, having it measured is worth more.
We wrote a separate piece on B12 deficiency in older adults.
What if your thyroid is underactive?
An underactive thyroid can slow your thinking, leave you feeling cold and drain your energy. When TSH is clearly raised, treatment makes sense. When TSH is only mildly raised the picture is more nuanced, and the link with cognitive complaints is contested (Wilson et al., 2022).
That nuance matters. Not every slightly abnormal TSH explains your symptoms, and not every abnormality needs treating.
I add that because people holding a result in their hand sometimes settle on an explanation too quickly. Your GP looks at the whole picture.
Can anaemia cause forgetfulness?
Yes, it can. With anaemia your blood carries less oxygen, and you notice that in your energy and your concentration. In the Health ABC study of more than 2,500 older adults, anaemia was associated with a higher risk of dementia in the years that followed (Hong et al., 2013).
That does not mean anaemia causes dementia. An association is not a cause.
More on the causes in anaemia in older adults.
An example from practice
An example helps here. Picture a woman of 71 who has taken a stomach acid inhibitor for four years. She is tired, forgets more than she used to, and sometimes has tingling fingers. Her B12 comes back at 128 pmol/l and her haemoglobin at 6.9 mmol/l, both too low.
Two values, and a story that fits.
After the deficiency is treated, things are reviewed again three months later. If the complaints persist, the GP looks further. But you start with what you can repair.
When is this not enough?
When your blood values are fine and your memory still declines within months, blood work has finished its job. Your GP then looks further with a conversation, a memory test and, if needed, a referral. The Hersenstichting and the RIVM describe the same order.
Treatable causes are not often the explanation, but you want to rule them out first (Muangpaisan et al., 2012).
What those next steps look like is covered in is there a test for dementia. If you are unsure whether your forgetfulness is even abnormal, read when forgetfulness is normal. And for the bigger picture: preventing dementia.
If you want this list checked at a calm moment, a vitamin and iron panel covers part of it.
References
- Clarke R, et al. (2012). Vitamin B12 status, cognitive decline and dementia: a systematic review of prospective cohort studies. Br J Nutr. PMID 23084026.
- Wilson S, et al. (2022). Subclinical Hypothyroidism and Cognitive Impairment. J Alzheimers Dis. PMID 35694927.
- Hong CH, et al. (2013). Anemia and risk of dementia in older adults: findings from the Health ABC study. Neurology. PMID 23902706.
- Muangpaisan W, et al. (2012). Prevalence of potentially reversible conditions in dementia and mild cognitive impairment in a geriatric clinic. Geriatr Gerontol Int. PMID 21794050.
- Hersenstichting. Memory complaints: what can you do? hersenstichting.nl.
- RIVM. Figures on dementia in the Netherlands. rivm.nl.
Would you like these blood values checked at a calm moment, without first booking an appointment with your GP? At Levenswijs Health you can. Every result is reviewed by a doctor registered in the Dutch BIG register. A blood test does not provide a diagnosis and cannot detect dementia. For treatment decisions, always discuss your results with your GP.
Author
