6 dementia symptoms that can appear years before diagnosis

Although impaired memory and thinking are the most common symptoms of dementia, noncognitive symptoms of the disease can emerge years or even decades earlier. For example, the first stage of Alzheimer's disease, which accounts for 60% to 80% of dementia cases, can begin 15 to 20 years before a person experiences any obvious changes to their cognition.

According to researchers, biological changes during the early stages of Alzheimer's disease could lead to emotional, sensory, and physical symptoms years before a potential diagnosis is made. Some early symptoms that often appear in people who are later diagnosed with dementia include:

1. Depression and anxiety later in life

In a 2023 study of 1.4 million Danish adults, researchers found that the risk of dementia was 2.4 times higher in people diagnosed with depression — making it a known risk factor of dementia.

However, health experts say that depression and anxiety that develops later in life, such as around age 55 or 60, could also be a warning sign for dementia.

"The idea is that some of the brain network changes that are happening early in dementia affect your mental health as well," which suggests changes to mental health are "a signal for early potential changes in brain function," said Timothy Chang, an associate professor of neurology at the University of California, Los Angeles.

2. Increased apathy, irritability, or agitation

Irritability and agitation are common neuropsychiatric symptoms found in Alzheimer's disease and usually occur before cognitive decline. In a 2017 study of 1,400 adults, researchers found that 54% of people with mild cognitive impairment and 47% of people with increased dementia risk had mood symptoms compared to 31% of cognitively healthy adults.

"If you just feel like you're mad and grumpy all the time, and you're snapping at people and your relationships with people seem to be highlighted by kind of consistent fighting and kind of negative vibes, then go seek mental health support" from a geriatric psychiatrist, said Adam Turnbull, an instructor in psychiatry and behavioral sciences at Stanford University.

3. Sleep problems

According to a 2025 meta-analysis of 39 studies, sleep apnea and other sleep disorders, such as excessive daytime sleepiness or restless leg syndrome, are associated with an increased risk of dementia.

A separate study of over 4,400 cognitively healthy older adults also found that having less nighttime sleep or more daytime sleep was associated with a higher accumulation of amyloid beta, a biological marker of Alzheimer's disease.

Meanwhile, getting an additional hour of nighttime sleep has been associated with reduced amyloid beta levels, with research suggesting that sleep may help remove waste, including amyloid beta, from the brain. 

5. Slower walking

Although slower walking has long been believed to be a normal part of aging, new research suggests that these changes can precede and potentially predict cognitive impairment and other neurological issues.

In a 2024 study of more than 1,300 adults over the age of 65, researchers found that walking speed and the ability to turn 360 degrees declined up to a decade before symptoms of cognitive decline emerged. 

6. Weakened grip strength

Weaker grip strength has been associated with worse cognitive health. In a recent study with over 190,000 adults, researchers found that every 11-pound decrease in grip strength was associated with a 20% increase in dementia for men and a 12% increase for women. Weaker grip strength was also associated with lower problem-solving scores and worse performance on a memory task.

Weaker grip strength can also indicate physical frailty, which is a risk factor for dementia and a potential warning sign that can appear around a decade before cognitive symptoms begin.

According to health experts, having early symptoms linked to increased dementia risk doesn't necessarily mean you'll develop the disease, but if you're concerned about any symptoms, you should talk to your doctor.

"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.

The new guidance also includes a greater focus on environmental risk factors, including exposure to polluted air. Currently, WHO estimates that 99% of the global population is exposed to air pollution levels that exceeded the organization's recommended limits.

WHO also highlighted brain stimulation and learning as ways to maintain cognitive activity. Learning new skills, engaging in mentally challenging activities, and continuing your education can all help reduce dementia risk. Increasing social engagement, including through volunteering or regular interaction with friends and family, can also help protect cognitive function over time.

However, WHO also noted that there are certain strategies it cannot yet recommend due to insufficient evidence. Taking certain supplements (Vitamin B, E, Omega-3, or multivitamins), menopausal therapy, managing depression, and improving sleep were not specifically recommended as ways to improve cognitive function or reduce dementia risk.

Overall, "[t]he biggest change is that WHO is starting to frame dementia as something that can be prevented instead of something families inevitably have to prepare for," said Faris Flournoy, CEO of Flournoy Health Systems. "These guidelines mark one of the first times the WHO has provided clear recommendations for reducing dementia risk, giving families hope and making healthy aging more accessible."