The loss of dopamine with age is thought to be responsible for many neurological symptoms that increase in frequency with age, such as decreased arm swing and increased rigidity. Changes in dopamine levels may also cause age-related changes in cognitive flexibility. Serotonin
Decreasing levels of different serotonin receptors and the serotonin transporter, 5-HTT, have also been shown to occur with age. Studies conducted using PET methods on humans, in vivo, show that levels of the 5-HT2 receptor in the caudate nucleus, putamen, and frontal cerebral cortex, decline with age. A decreased binding capacity of the 5-HT2 receptor in the frontal cortex was also found, as well as a decreased binding capacity of the serotonin transporter, 5-HHT, in the thalamus and the midbrain. Postmortem studies on humans have indicated decreased binding capacities of serotonin and a decrease in the number of S1 receptors in the frontal cortex and hippocampus as well as a decrease in affinity in the putamen. Glutamate
Glutamate is another neurotransmitter that tends to decrease with age. Studies have shown older subjects to have lower glutamate concentration in the motor cortex compared to younger subjects A significant age-related decline especially in the parietal gray matter, basal ganglia, and to a lesser degree, the frontal white matter, has also been noted.
Nun Study
A study funded by the National Institute of Aging followed a group of 678 Roman Catholic sisters and recorded the effects of aging. The researchers used autobiographical essays collected as the nuns joined their Sisterhood. Findings suggest that early idea density, defined by number of ideas expressed and use of complex prepositions in these essays, was a significant predictor of lower risk for developing Alzheimers disease in old age. Lower idea density was found to be significantly associated with lower brain weight, higher brain atrophy, and more neurofibrillary tangles. Hypothalamus inflammation and GnRH
In a recent study (published May 1, 2013), it is suggested that the inflammation of the hypothalamus may be connected to our overall aging bodies. They focused on the activation of the protein complex NF-κB in mice test subjects, which showed increased activation as mice test subjects aged in the study. This activation not only affects aging, but affects a hormone known as GnRH, which has shown new anti-aging properties when injected into mice outside the hypothalamus, while causing the opposite effect when injected into the hypothalamus. Itll be some time before this can be applied to humans in a meaningful way, as more studies on this pathway are necessary to understand the mechanics of GnRHs anti-aging properties. Inflammation
A study found that myeloid cells are drivers of a maladaptive inflammation element of brain-ageing in mice and that this can be reversed or prevented via inhibition of their EP2 signalling. Aging disparities
For certain demographics, the effects of normal cognitive aging are especially pronounced.