We鈥檝e all been there. You walk upstairs only to find yourself wondering why you bothered. You blank on an acquaintance鈥檚 name, just as you鈥檙e introducing them. Or maybe, after a frantic search, you find your car keys in the fridge of all places.
Such momentary lapses of memory can be disconcerting, but they are part and parcel of getting older, and very much to be expected. 鈥淒ecline in what researchers call episodic memory 鈥� what happened, where and when 鈥� is a normal part of human cognitive ageing,鈥� says , a cognitive neuroscientist and director of the Max Planck Institute for Human Development in Berlin. 鈥淚n most adults, decline becomes apparent in their 60s鈥� and it affects all stages of memory, from the encoding of new events over consolidation to retention and recall.鈥�
This is largely explained by structural and functional changes to the brain that begin in middle age and accelerate from there. In a 2025 paper analysing more than 3700 鈥渃ognitively healthy鈥� adults, Lindenberger and his colleagues found , itself the result of the gradual degradation of the fatty coating that insulates neurons, and shrinkage of the hippocampus 鈥� a brain region crucial in forming new memories.
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This is nothing to worry about, says Lindenberger. 鈥淟earning and episodic memory are all about forming new, and remembering previously formed, associations 鈥� and the corresponding machinery of our brains becomes less reliable with advancing adult age.鈥�
What鈥檚 more, in many cases, everyday memory failures are actually just failures of attention: if your brain never properly encoded where you put your keys because you were distracted or stressed in the moment, there isn鈥檛 much in the way of memory to retrieve later.
Where 鈥渘ormal鈥� memory slowdown becomes something more suspicious, however, is harder to say.
Broadly speaking, neurologists themselves take notice when incidental forgetfulness becomes a pattern that interferes with daily functioning 鈥� when you forget things you used to remember, or when you forget important things 鈥� and when memory loss accelerates in such a way that others notice. 鈥淲e get concerned when individuals start to forget important information like doctor鈥檚 appointments or golf tee times,鈥� says , a neurologist at the Mayo Clinic in Minnesota. 鈥淲hen it starts to become a pattern and those around you notice these episodes, it might be time to seek attention.鈥�
Petersen says one way to think about what constitutes a pattern might be to think about whether you, or someone you鈥檙e concerned about, repeats themselves 鈥� and crucially, how frequently 鈥� because that can serve as a decent metric for the extent to which memory function may be declining in an accelerating fashion. 鈥淭ending to repeat oneself, without awareness, on a frequent basis鈥� that might be worrisome,鈥� says Petersen.
The reason conversational repetition is a good indicator has to do with what happens in the brain in mild cognitive impairment, the transitional stage between typical ageing and dementia, and early-stage dementia. In Alzheimer鈥檚 disease, by far the most common form of dementia, 鈥� meaning that people affected struggle disproportionately with forming new memories, of a recent conversation, for instance, rather than with recalling established memories. If someone asks the same question several times in the space of an afternoon, it may be because the memory of asking the question never properly formed in the first place 鈥� which is a potential red flag.
Whether it鈥檚 conversational repetition or getting lost in familiar places, another widely cited cause for concern, there is no hard-and-fast rule when it comes to what kinds of forgetfulness indicate something more serious than typical age-related memory loss. 鈥淚n advanced old age, the line between the lower range of normal [age-related memory decline] and dementia is difficult to draw,鈥� says Lindenberger. Put simply, the problem is that there isn鈥檛 a sharp distinction, in terms of behaviour, or even biology, between the two.
Everything from anxiety, stress and depression to menopause and medications have been shown to temporarily impair attention and episodic memory. So, it is always worth considering what else might lie behind signs of cognitive impairment before jumping to conclusions. We should also be wary of over-interpretation. A 2025 study showed that than those in a control group, which is itself associated with negative health outcomes.
The truth is that knowing what is 鈥渘ormal鈥� and when to worry about memory loss in old age is difficult even for neurologists 鈥� never mind for the rest of us. Ultimately, then, perhaps the best rule of thumb is, as Lindenberger says, that 鈥渢here is reason to be concerned when [memory] decline is fast and starts to interfere with daily routines鈥�.
