A new study conducted at Edith Cowan University has identified an important link between genetics and sleep habits that may influence early brain changes associated with Alzheimer’s disease long before clinical symptoms appear.

The findings were published in the journal Alzheimer’s & Dementia.

The researchers focused on the AQP4 (aquaporin-4) gene, which regulates fluid movement in the brain. This mechanism is connected to the brain’s so-called “waste clearance system,” which is most active during sleep. Scientists believe this system helps remove proteins associated with neurodegenerative diseases, including Alzheimer’s disease.

The team analyzed 13 common variants of the AQP4 gene, participants’ sleep patterns, MRI brain scans, and measures of cognitive function. The results showed that the impact of sleep on the brain may depend significantly on an individual’s genetic variant.

Among people carrying certain AQP4 variants, shorter sleep duration was associated with a faster reduction in gray matter volume. In other participants, difficulties falling asleep were linked to structural brain changes and similar adverse effects.

In other words, the same factor—sleep disturbance—may affect the brain differently depending on a person’s genetic makeup. For some individuals, it appears to accelerate gray matter loss, while for others it is associated with different structural changes and cognitive consequences.

The researchers emphasize that this reflects a complex interaction between heredity and lifestyle. As study co-author Ayesha Milligan-Armstrong noted, “the same genetic variants can be either protective or harmful depending on how a person sleeps.”

The team also examined cognitive changes among participants and found that patterns of cognitive decline over time varied according to the combination of sleep disturbances and genetic profile.

According to the researchers, these findings reinforce the idea that Alzheimer’s disease risk cannot be viewed as a single pathway that applies to everyone. Even among people with similar levels of risk factors, the pace of brain changes may differ considerably.

One potential long-term goal of this line of research is to determine whether improving sleep in individuals with specific genetic variants could slow or alter brain changes associated with neurodegenerative processes.