Sleep disturbances, a diminished sense of smell, slower walking speed, and reduced handgrip strength are among the early symptoms that may appear years before a formal dementia diagnosis, according to recent research.

Sleep disorders such as sleep apnea, excessive daytime sleepiness, restless leg syndrome, and disruptions in circadian rhythms have been linked to a heightened risk of dementia. A 2025 meta-analysis examining 39 studies found a correlation between these conditions and cognitive decline. Insufficient nighttime sleep or excessive daytime napping has also been associated with an increased buildup of amyloid beta, a protein linked to Alzheimer’s disease, in the brain. Conversely, longer durations of nighttime sleep appeared to lower amyloid beta levels. This suggests that sleep may play a role in clearing neurotoxic waste from brain tissue. Experts caution that occasional naps are not problematic, but excessive daytime sleep combined with poor nighttime rest could warrant further evaluation.

A reduced ability to smell is another early indicator of neurodegenerative disorders, including Alzheimer’s and Parkinson’s disease. Studies show that approximately 85 percent of individuals in the early stages of Alzheimer’s experience olfactory impairments. The olfactory nerve’s unique direct connection to brain regions involved in memory, cognition, and mood—such as the hippocampus and amygdala—may explain why loss of smell precedes other symptoms. Encouragingly, the olfactory nerve can regenerate, and some preliminary evidence suggests that smell training may improve cognitive function even in those with normal olfactory abilities.

Changes in gait, including slower walking speed, shorter steps, and wider stride, were once considered typical signs of aging but are now recognized as potential early markers of cognitive decline. A 2024 study tracking over 1,300 adults aged 65 and older found that diminished walking ability, including difficulty turning 360 degrees, could be detected up to a decade before the onset of cognitive impairment.

Handgrip strength has also emerged as a significant predictor of dementia risk and overall health. Analysis of more than 190,000 adults indicated that decreases in grip strength were linked to a higher incidence of dementia, with every 11-pound reduction corresponding to a 20 percent increased risk in men and 12 percent in women. Weaker grip strength was further associated with poorer memory and problem-solving performance. Physicians often use grip strength, combined with walking assessments, to evaluate physical frailty—a condition that increases vulnerability to illness and is considered both a risk factor and early warning sign for dementia.

Medical experts advise that while these symptoms deserve attention, they do not necessarily indicate dementia. Those experiencing such changes alongside memory concerns should consult healthcare providers for comprehensive evaluation. Recent advances in diagnostic methods, including positron emission tomography (PET) scans, lumbar punctures, and blood tests, have improved the ability to detect early disease biomarkers and may facilitate timely treatment.

Although genetics play a role in dementia risk, lifestyle interventions have shown promise in reducing that risk. The 2025 U.S. POINTER trial demonstrated that combining exercise, a balanced diet, social engagement, and cognitive activities can enhance cognitive function in older adults at risk for decline. Other research supports the benefits of alcohol moderation, regular vaccination, and hearing protection to maintain brain health.