How does the thymus gland change as a person ages, particularly in terms of its size and function?

As a person ages, the thymus gland tends to decrease in size and function. This is because the thymus gland is most active during childhood and adolescence, producing T-cells that are important for the immune system. However, as we get older, the thymus gland gradually shrinks and becomes less efficient in producing T-cells, leading to a decline in immune function.