Reviewed for medical accuracy by Dr Evelyne Jonniaux, Medical Advisor
Last updated 17 September 2026
Most memory complaints do not become dementia. In the largest meta-analysis of mild cognitive impairment, the annual conversion rate to dementia is 2.33 percent per year in community samples. Over five years, the great majority of people with a memory complaint have not converted.
The questions we get asked
What does a memory complaint actually predict?
Mitchell and Shiri-Feshki pooled 41 cohorts and found a cumulative conversion to dementia of 9.6 percent over the studies in community samples, corresponding to roughly 2.33 percent per year. Specialist clinic populations convert faster, which is expected because they are selected. The figure often quoted in the press, 10 to 15 percent per year, comes from clinic cohorts and does not describe someone who noticed they forget names.
Can mild cognitive impairment go the other way?
Yes, and this is the part that is routinely left out. Reversion to normal cognition is documented in 14 percent of clinic-based cohorts and 31 percent of community-based cohorts. A diagnosis of mild cognitive impairment is not a one-way door, and a single assessment is a poor basis for a prognosis.
How often is a treatable cause found?
Clarfield reviewed the literature on reversible dementias and separated two numbers that are usually merged. Around 9 percent of cases have a potentially reversible cause identified, most often depression, thyroid disease, vitamin B12 deficiency, or medication effects. But the proportion that actually reverses after treatment is 0.6 percent. The workup is still worth doing, because the alternative is missing the treatable minority, but it should be presented for what it is.
What do the new drugs change?
Lecanemab produced a difference of 0.45 points on the CDR-Sum of Boxes scale at 18 months against placebo. The minimum clinically important difference proposed for that scale in mild cognitive impairment is 1 to 2 points. The statistical result is real, the effect is below the threshold that has been argued to be perceptible to a patient or family, and the treatment requires infusions and MRI monitoring for amyloid-related imaging abnormalities.
What the figures say
| Finding | Figure | Source |
|---|---|---|
| Annual conversion of MCI to dementia, community samples | 2.33 percent per year | Mitchell and Shiri-Feshki, Acta Psychiatr Scand, 2014 |
| Reversion of MCI to normal cognition | 14 percent clinic, 31 percent community | Pooled cohort data |
| Potentially reversible cause identified | 9 percent | Clarfield, Arch Intern Med |
| Cases that actually reversed after treatment | 0.6 percent | Clarfield |
| Lecanemab effect at 18 months, CDR-SB | 0.45 points, MCID 1 to 2 points | Clarity AD trial |
One figure we could not source: the frequently repeated claim that a memory complaint in a person over 60 carries a fixed multiple of dementia risk. The studies we found report widely different hazard ratios depending on how the complaint was elicited, and we do not consider a single number defensible.
What Noria Health does, and does not do
We organise a structured cognitive assessment with a neurology team near Brussels: standardised testing, biological workup for reversible causes, and imaging where it is indicated. We confirm feasibility within 24 to 48 hours, and the report is sent at D14, D30 and D90 where follow-up applies.
We do not screen remotely, we do not interpret a test result by message, and we do not advise on treatments that have not been prescribed by the treating team.
Who reviewed this page
Noria Health editorial team.
See also: all our articles on neurology.
Have your case reviewed. Noria Health arranges a specialist consultation near Brussels and confirms feasibility within 24 to 48 hours. Open a case.