Saudi researcher explores how anxiety represses body's immune responses

Stress, anxiety and chronic sleep loss can erode the body’s natural defenses, increasing vulnerability to infections, cancer and autoimmune conditions. Scientists have now identified a possible biological pathway that may help explain how psychological strain translates into weakened immunity.

In a study published in early December, researchers focused on a class of immune cells known as natural killer (NK) cells, which appear to play a central role in this connection, as highlighted in an article by Frontiers.

The work was partly motivated by a 2022 national screening study in Saudi Arabia that found rates of generalized anxiety disorder (GAD) were rising, particularly among women. People with GAD experience persistent and uncontrollable worry that is disproportionate to real-life situations, often accompanied by symptoms such as irritability, restlessness and sleep disturbances.

Prompted by these findings, immunologist and lead author Renad Alhamawi of Taibah University in Medina set out to examine how anxiety might influence immune function in women.

Alhamawi and her team recruited 60 female students aged 17 to 23 and asked them to complete questionnaires assessing their mental health. The results showed that 75 per cent reported symptoms consistent with GAD, including 13 per cent who fell into the severe category. More than half of the participants — 53 per cent, or 32 students — also said they were not getting enough sleep.

Blood samples were then collected and analyzed to measure different types of immune cells. The analysis revealed that participants with anxiety-like symptoms had 38 per cent fewer NK cells than those who did not report such symptoms.

NK cells are among the immune system’s first responders to infections and cancerous changes in the body. They are generally divided into two subsets: one that destroys abnormal or infected cells by releasing toxic enzymes, and another that produces signalling proteins, known as cytokines, to coordinate broader immune responses. A decline in these cells could leave individuals more susceptible to disease.

The study found that participants with anxiety symptoms had lower levels of both NK cell subsets. By contrast, those who reported insufficient sleep showed a 40 percent reduction only in the immune-regulating subset.

Crucially, the researchers emphasized that their findings show correlation rather than causation. The study did not establish whether anxiety or sleep deprivation directly causes NK cell depletion, nor whether reduced NK cell levels lead to higher disease risk.

The results align with earlier research, including studies on chronic tinnitus, where higher stress levels were associated with fewer cell-killing NK cells. Alhamawi suggested that cortisol, a hormone released during stress, may play a role, as it is known to suppress various aspects of immune function, including antigen-specific T cells that target specific threats such as viruses.

"Anxiety increases the level of cortisol, so we think it might affect the number of NK cells in an indirect way," Alhamawi said.

One major limitation of the study is its small and narrowly defined sample, which included only women under 25 from a single ethnic background. Alhamawi said she hopes to conduct a longer-term study that follows the same participants over time, tracking changes in anxiety, sleep patterns and NK cell levels. Such research could offer clearer insight into how psychological stress affects immunity and whether it ultimately influences disease risk.

By Nazrin Sadigova