Beyond the Fog

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Impaired memory and thinking are the most common symptoms associated with a dementia diagnosis. But non-cognitive symptoms can appear years or even decades earlier.Alzheimer’s disease, which accounts for 60 to 80 per cent of dementia cases, progresses through three main stages. The first can begin 15 to 20 years before any obvious changes to cognition. During this period, the brain starts to shrink and the misfolded proteins that are hallmarks of Alzheimer’s – sticky amyloid beta plaques and tau tangles in neurons – begin to build up.This is followed by mild cognitive impairment, where people experience noticeable problems with memory and cognition but retain good overall function. The final stage is dementia, when multiple cognitive abilities are impaired, making it difficult to function in everyday life.Scientists think the biological changes in the brain during the first two stages may cause emotional, sensory and physical symptoms years before a diagnosis. “You can have many of these other precursors but not have any cognitive symptoms,” said Timothy Chang, an associate professor of neurology at UCLA. Experts caution that having early symptoms linked to an increased risk of Alzheimer’s does not necessarily mean you will develop dementia. Around 45 per cent of dementia cases are considered preventable through lifestyle changes.Depression and anxiety that start later in lifeDepression is a known risk factor for dementia. A 2023 study of more than 1.4 million Danish adults found that the risk of dementia was 2.4 times higher in those diagnosed with depression.Depression and anxiety that develop later in life – around the age of 55 or 60 – can also be warning signs that something may be changing in the brain.“The idea is that some of the brain network changes that are happening early in dementia affect your mental health as well,” Chang said. Changes to mental health may therefore be “a signal for early potential changes in brain function.”Researchers have also found that these mood symptoms may accelerate the progression of dementia.Neuropsychiatric symptoms such as irritability and agitation are common in Alzheimer’s disease and can occur before cognitive decline becomes apparent.A 2017 study of around 1,400 people found that 31 per cent of older adults with healthy cognition experienced mood symptoms. This figure rose to 47 per cent among those at increased risk of dementia and 54 per cent among people with mild cognitive impairment.According to Adam Turnbull, an instructor in psychiatry and behavioural sciences at Stanford University, around 50 to 60 per cent of people with biomarkers of Alzheimer’s pathology have at least one neuropsychiatric symptom.“If you just feel like you’re mad and grumpy all the time, and your relationships with people seem to be highlighted by kind of consistent fighting then go seek mental health support” from a geriatric psychiatrist, Turnbull said.Problems with sleepBecause sleeping well can help protect brain health, poor sleep cycle may indicate that something is wrong.Sleep apnoea and other sleep disorders, including excessive daytime sleepiness, restless leg syndrome and circadian rhythm sleep disorders, are associated with an increased risk of dementia, according to a 2025 meta-analysis of 39 studies. Insomnia and reduced night-time rest can also precede dementia. One study of more than 4,400 cognitively healthy older adults found that less sleep at night or more sleep during the day was linked to increased accumulation of amyloid beta in the brain.By contrast, each additional hour of night-time sleep was associated with lower amyloid beta levels. Research suggests that sleep may help flush waste products, including amyloid beta, from the brain. Turnbull said there is no need to worry about an occasional afternoon nap. However, an afternoon nap is not a cause for concern. However, sleeping excessively during the day and poorly at night may be.Loss of sense of smellOur sense of smell is closely linked to brain health, and its loss is often one of the earliest signs of neurodegenerative diseases, including Alzheimer’s and Parkinson’s. About 85 per cent of people with early-stage Alzheimer’s experience problems with their sense of smell.The nose has a unique connection with the brain. Unlike hearing or sight, smell information is sent more directly to the cortex and then to areas involved in cognition, memory and mood, including the hippocampus and amygdala.Interestingly, the olfactory nerve can regenerate, and people may improve their sense of smell through training and thearapy.Slower walkingChanges such as walking more slowly, or having a wider stride were once thought to be a normal part of ageing. Research now suggests that these changes can precede and predict cognitive impairment and other neurological problems. A 2024 study of more than 1,300 healthy adults aged over 65 found that walking ability, and the ability to turn 360 degrees, declined up to a decade before cognitive impairment became evident. Research now suggests that these changes can precede and predict cognitive impairment and other neurological problems.Weaker handgrip strengthGrip strength is closely linked with healthy ageing and may even be a better indicator of life expectancy than blood pressure.Weaker grip strength is also associated with poorer cognitive health. A recent study involving more than 190,000 adults found that every 11-pound decrease in handgrip strength was associated with a 20 per cent increase in dementia risk in men and a 12 per cent increase in women. It was also linked to poorer problem-solving skills and worse performance on memory tasks. including walking speed and the ability to turn 360 degrees, declined up to a decade before cognitive impairment became evident.When to talk to your doctor“If you’re an older adult noticing these symptoms, I wouldn’t panic and assume it’s dementia,” Turnbull said. “There’s a good chance it’s not anything to do with anything neurological.”However, if concerns about memory or thinking occur alongside these symptoms, experts recommend speaking to a doctor. Recent advances in diagnostics, including PET scans, lumbar punctures and blood tests, can detect Alzheimer’s biomarkers earlier and may help speed up treatment.“I think it’s good to have an evaluation and have a physician kind of give feedback on like, oh, this is concerning or it’s not,” Chang said.