Vascular Degeneration in the Brain Correlates with Behavioral Change in Old Mice
The research here is an interesting view on the relevance of vascular aging in cognitive decline and later dementia. The researchers find similar changes in blood vessels in both old mice and mice engineered to undergo the amyloid and tau aggregation characteristic of human Alzheimer's disease. In humans, a sizable proportion of people suffering Alzheimer's disease also have vascular dementia - one of the many challenges facing any group trying to prove success in a therapy intended to narrowly address aspects of Alzheimer's biochemistry. That success, if it takes place at all, could well be masked in many patients by the loss of function that results from vascular aging.
With age, blood vessels stiffen and are weakened by corrosive fatty deposits. Blood pressure rises, causing an increase in the breakage of small blood vessels and consequent damage to surrounding tissue. The heart weakens. Capillary growth into tissues declines for reasons that are still comparatively poorly understood. Further, the amyloid associated with Alzheimer's can also emerge in blood vessels and cause dysfunctional behavior there. The brain is an energy-hungry organ, and all of these problems combine to reduce the supply of needed oxygen and nutrients. Dementia is the end result. That so many of these processes of harm are accelerated by chronic inflammation, such as that produced by excess fat tissue, is why a number of forms of dementia appear to have a strong lifestyle component - Alzheimer's included.
Researchers have demonstrated for the first time that anxiety and problems with blood vessels present a close relationship with Alzheimer's disease, which particularly affects females. Vascular disease resulting from oxidative stress and inflammation is gaining clinical interest, given that subsequent cardiovascular insufficiency can alter the blood flow distribution to different organs and tissues, including the brain, which can worsen a pathology related to this type of dementia.
The research provides the first evidence that mice of advanced ages suffering from Alzheimer's disease present substantial alterations in small blood vessels, which are essential in nourishing different organs and tissues and in the regulation of blood pressure. "The study demonstrates that the sex of the mice is a determining factor. It is specifically the female mice which show more pronounced vascular alterations, which suggests that women of advanced ages suffering from Alzheimer's disease may suffer more from cardiovascular malfunctions."
The characteristics of small arteries were studied under different physiological conditions. Further research revealed that these vascular changes appear in both the vascular structure and function, which suggests an abnormal distribution in peripheral blood flow. Researchers also assessed animal behaviour. This allowed them to discover the existence of a strong relation between the vascular parameters analysed - structure, elasticity, function - and different patterns of anxiety in mice models of Alzheimer's, but also in mice ageing normally.
"Although we must be cautious with these results, the correlation of behaviours propose the existence of direct or indirect relations between conduct and the function of peripheral arteries. These interactions may be able to explain the anomalies of the neuro-immuno-endocrine system, which regulates the performance of different organs and tissues."