Primitive reflexes that fade in infancy but resurface in older adults may be an early warning sign of dementia risk, according to a 19-year study of over 870 participants. Researchers found that healthy adults with two or more of these reflexes faced nearly twice the risk of developing dementia within seven years compared to those without them.

What Are Primitive Reflexes and Why Do They Matter?

Primitive reflexes, also called frontal release signs, are involuntary responses that are normal in infants but typically disappear as the brain matures. Examples include the palmar reflex, where a baby grips anything placed in their palm, and the snout reflex, where lips pucker when the area around the mouth is tapped. When these reflexes reappear in adults, they often signal brain injury or neurodegenerative disease.

The University of Kentucky Alzheimer's Disease Research Center conducted a long-term study tracking 873 volunteers aged 70 and older from September 2005 through November 2024. Among the 672 participants with healthy brain function at the start, those with two or more primitive reflexes showed significantly higher dementia risk. About 25.4% of healthy participants with these signs progressed to dementia over the study period, compared with 14.5% of those without them. In other words, roughly 1 in 4 people with multiple reflexes developed dementia, versus about 1 in 7 without them.

How Can Doctors Use This Information to Screen for Dementia Risk?

One major advantage of primitive reflexes as a screening tool is accessibility. Unlike advanced brain imaging such as MRI or PET scans, or invasive tests like spinal taps, these reflexes can be assessed by any doctor during a routine office visit. This makes them a practical option for identifying people at higher risk, especially in settings where specialized dementia testing is unavailable.

During the study, doctors evaluated five specific primitive reflexes during annual assessments:

• Grasp reflex: An involuntary gripping response when something is placed in the palm
• Snout reflex: Lip puckering or movement when the area around the mouth is tapped
• Palmomental reflex: A chin twitch triggered by stroking the palm
• Glabellar tap response: Persistent blinking when the forehead is tapped repeatedly
• Fifth reflex: The study assessed five frontal release signs in total, with these four being the primary ones detailed in the research

Healthy participants who showed these signs also experienced a slight but measurable decline in memory and executive function over time, even before dementia developed. However, the reflexes did not predict dementia risk among people who already had mild cognitive impairment, suggesting they may be most useful as an early warning in cognitively healthy adults.

What Does This Mean for Early Dementia Detection?

As dementia cases continue rising worldwide, early detection has become increasingly important. People diagnosed early can access emerging treatments sooner and maintain their quality of life longer. Current methods for detecting early dementia involve blood biomarkers such as amyloid-beta, tau proteins, and neurofilament light chain (NfL), which can identify disease signs before symptoms appear. However, these tests require specialized facilities and expertise that are not always readily available.

Primitive reflexes offer a noninvasive alternative that requires no special equipment or expertise beyond a doctor's clinical assessment. While researchers emphasize that these reflexes are not sensitive enough to serve as a standalone screening tool, they may provide valuable information when combined with other clinical assessments and screening measures.

Steps to Discuss Primitive Reflexes With Your Doctor

• Mention family history: If dementia runs in your family, inform your doctor so they can be alert for early warning signs during your examination
• Request reflex assessment: Ask your doctor to check for primitive reflexes during your next annual physical or cognitive screening visit
• Track cognitive changes: Keep notes on any memory lapses or thinking difficulties you notice and share them with your healthcare provider at appointments
• Combine screening methods: Discuss whether blood biomarker testing or brain imaging might be appropriate alongside reflex assessment for a more complete picture

The researchers acknowledge that their study was limited to a single research center, so broader studies across diverse populations and clinical settings are needed to confirm whether these findings hold true more widely. Still, the results suggest that a simple, noninvasive assessment during routine doctor visits could help flag people at higher risk of cognitive decline before symptoms become obvious.

For older adults concerned about dementia risk, this research offers a practical starting point for conversation with their healthcare provider. A brief reflex check during an annual exam costs nothing, requires no special equipment, and could help identify those who might benefit from closer monitoring or early intervention strategies.