Scientists identified one potential mechanism underlying the impaired cognitive abilities associated with diabetes.
Cortisol production is controlled by the hypothalamic-pituitary axis (HPA). People with poorly controlled diabetes often have an overactive HPA axis, and the adrenal gland produces excessive cortisol.
To study the interaction between elevated stress hormones and the hippocampal function, researchers tested cognitive abilities and examined brain tissue in rat models of type 1 diabetes and mice with type 2 diabetes.
They found that diabetic animals in both models exhibited learning and memory deficits when cortisol levels were elevated due to impaired plasticity and a decline in new cell growth. Returning the levels to normal, however, reversed the negative impact on the hippocampus and restored learning and memory.
The scientists note that this might also explain the connection between stress-related mood disorders and diabetes found in human population studies.
The research was conducted by investigators at the NIA and a graduate student at Princeton University. The study appeared in the February 17 issue of Nature Neuroscience.