Expert outlines five differences between brain fog and early Alzheimer's
Dementia specialist says brain fog is usually temporary and reversible; persistent or progressive memory problems should prompt medical assessment
A dementia expert has set out five practical ways to distinguish common, usually temporary "brain fog" from potential early signs of Alzheimer's disease, stressing that persistent or worsening problems should prompt medical assessment.
Emma Taylor, information services manager at Alzheimer's Research UK, told The Sun that the key distinction is duration and reversibility: "The biggest difference between brain fog and Alzheimer's is that the brain fog is temporary and often reversible." Figures from Alzheimer's Research UK show 74,261 people died from dementia in the United Kingdom in 2022, up from 69,178 the year before, making Alzheimer's the country's most common cause of death.
Taylor outlined five everyday behaviours that patients, families and clinicians can use to assess whether lapses are likely benign or warrant further evaluation: walking into a room and forgetting why, misplacing keys, having trouble finding the right word, forgetting appointments, and losing the thread of a conversation. She said the pattern of those lapses matters.
Occasional absentmindedness, such as briefly forgetting why one entered a room or misplacing items but later finding them, is typically consistent with brain fog, which can be triggered by stress, tiredness or hormonal changes. By contrast, Taylor said that frequent, progressive problems — for example repeatedly putting keys in highly unusual places and not remembering doing so, or consistently failing to recall appointments even after reminders — should prompt a discussion with a general practitioner about possible dementia.
Language changes also differ, she said: struggling momentarily to retrieve a word that later comes to mind is more characteristic of brain fog, while regularly substituting unrelated words for common items can be an early sign of Alzheimer's. Similarly, mild sluggishness of thought that still allows one to follow a conversation points toward reversible causes; repeatedly losing track of what people are saying and asking the same questions are among warning signs Taylor highlighted.
Dr. Simon Wheeler, senior knowledge officer at the Alzheimer's Society, described brain fog as a symptom rather than a disease. "Although it’s not a disease or illness itself, it can be a symptom of common conditions including menopause, disorders, chronic pain and chronic fatigue syndrome," he told The Sun. Both experts urged people concerned about persistent symptoms to consult a GP, noting many causes of cognitive difficulty can be treated or managed.
Classic symptoms of dementia include worsening problems with memory, thinking speed, language, judgment and mood. Researchers have also linked early disease with lesser-known changes in senses and perception, including sight, hearing, touch, balance and, more recently, smell. Some clinicians have flagged problems with spatial awareness, such as standing unusually close to others, as possible early indicators.
Early diagnosis is considered important because, while Alzheimer's is currently incurable, treatments and interventions can help manage symptoms and sometimes slow progression. Alzheimer’s Research UK and the Alzheimer's Society offer tools and resources, including symptom checklists and guidance on talking to reluctant relatives. Taylor recommended keeping a diary of observed behavioural changes to support clinical evaluation.
Dementia affects large and growing numbers: more than 944,000 people in the U.K. are estimated to be living with the condition, and around seven million in the United States. Women make up an estimated 62% of people diagnosed with dementia in the U.K.; Taylor attributed part of that imbalance to hormonal changes linked to menopause, saying a drastic reduction in estrogen "leaves the brain more vulnerable to Alzheimer’s." The Alzheimer's Society has estimated the annual cost of dementia to the U.K. economy at about £42 billion, with projections that costs could rise to £90 billion over the next 15 years as the population ages.
Clinicians recommend that anyone noticing steady cognitive decline, new and persistent memory loss, or changes in everyday functioning seek medical evaluation. Short-term, reversible brain fog associated with identifiable causes such as stress, sleep loss or hormonal shifts is common, but professionals say distinguishing those cases from progressive cognitive disease is important to ensure timely care and support.