Forgetting a name or misplacing keys does not necessarily indicate dementia, experts say; stress, tiredness and lack of attention can make ordinary memory lapses more likely. Neuroscientist Tommy Wood says noticing a problem can be a reason to investigate and address its causes, rather than assume that cognitive decline is inevitable.

Wood describes memory as involving encoding, storing and retrieving information: stress or poor sleep may make memories harder to retrieve, while neurodegenerative disease can affect whether they are formed in the first place. Dementia is defined by cognitive loss that interferes with independent daily life; Alzheimer’s and vascular dementia account for an estimated 70% to 90% of cases. The article says at least half of dementia cases may be preventable through changes to health and lifestyle risks, including addressing heart and metabolic problems, hearing loss and vision loss.