Brain Atrophy, Lacunar Infarcts, and Dementia in the Elderly
Atrophy is a medical term meaning the shrinkage in size of cells, tissues, or organs that have already developed normally; it may be accompanied by a reduction in the number of parenchymal cells. Atrophy generally arises from lowered functional activity of cells, insufficient blood and nutrient supply, or reduced neural and/or endocrine stimulation. By cause it is divided into physiological atrophy and pathological atrophy. Brain atrophy in the elderly is physiological: in fact, with age, every organ of the elderly atrophies, and the older the person, the more marked the atrophy.
On MRI reports of the elderly we often see terms such as white-matter atrophy, gray-matter atrophy, and cerebellar atrophy. What do these terms mean, and what do they imply?
The cells of the brain are called neurons. In the human central nervous system (brain and spinal cord), the places where neuronal cell bodies and dendrites cluster are gray matter. It is called gray matter because these areas look grayish in fresh specimens. The gray matter on the surface of the cerebrum and cerebellum is called the cortex. So cerebral gray-matter atrophy essentially means the cell-body portion of brain cells is shrinking.
Besides the cell body, a neuron has another major part: its long process. Long processes transmit information; when wrapped in myelin they form nerve fibers. In the central nervous system, where nerve fibers cluster is called white matter, because the myelin sheaths look bright white. The white matter deep to the cerebral and cerebellar cortex is also called the medulla. Anatomical terminology is actually quite plain, though to non-medical listeners it sounds baffling at first.
With these concepts in mind, brain atrophy, white-matter atrophy, and gray-matter atrophy are easy to understand. They all essentially mean decline of brain cells, and these words appear frequently on the check-up reports of people over seventy. If an elderly relative's MRI report contains only these terms and no space-occupying lesion (brain tumor) or cerebral infarction, there is no need to panic; such findings are common in most older adults' MRIs.
The brain is divided into the cerebrum (telencephalon), diencephalon, midbrain, cerebellum, pons, and medulla oblongata; the cerebellum mainly governs fine movement and balance. Cerebellar atrophy is one of the most common words on MRI reports of the elderly; it means the cerebellum has atrophied, usually indicating that balance has worsened and fine movement is affected. At this point it is important to make preventive modifications to the older person's living and environment to prevent falls. A fall in an older person easily causes a comminuted fracture that heals slowly and very painfully.
Lacunar infarction is also one of the most common findings on check-up reports of people over seventy, and because it contains the word "infarction" it looks alarming. In reality, the great majority of people over seventy have lacunar infarcts. Lacunar infarction is a small-vessel blockage in the brain and is not the same as the "cerebral infarction" that causes stroke; the latter generally results from blockage of a medium-sized artery and is a more serious condition. Lacunar infarcts cause very mild symptoms; most older people are asymptomatic, though a few may have slight limb numbness or slurred speech.
Although brain atrophy and lacunar infarcts are inevitable physiological consequences of aging, measures can slow the process — this is a form of anti-aging. Lifelong learning is the best way to slow brain aging. Some neurologists point out that people who keep reading popular-science works from middle age have a greatly reduced probability of dementia in old age and a markedly better quality of life.
Findings in modern neurology show that the brain continues to develop throughout life. When a person studies or memorizes, the Nissl bodies in neurons produce more "memory proteins"; these not only make the brain smarter but also younger. However, prevention of brain decline is best begun in middle age rather than old age, because by then brain cells may already have suffered irreversible damage, and such "brain-nourishing" methods work poorly.
Medically speaking, cellular atrophy is a reversible adaptive change: when the external cause that produced the atrophy is removed, atrophy can be reversed. Although brain atrophy in the elderly cannot be fully reversed, by this theory we can hope to slow — and even modestly reverse — it by improving cerebral blood supply, protecting the vessels, and improving nutrition. Vitamin E protects the vascular intima, and the antioxidant effects of vitamin C and glutathione also protect our vessels.
With age, microvessels and capillaries inevitably develop small occlusions caused by tiny thrombi. Exercise and, under medical guidance, moderate use of blood-activating and stasis-resolving herbs have some thrombolytic effect. All our cells depend on blood to deliver nutrients and oxygen; for blood to flow unobstructed throughout the body, vessels must remain patent. If vessels are blocked, cells inevitably atrophy or even die for lack of nutrients and oxygen.
One major category of dementia is vascular dementia; recent research also shows that Alzheimer's disease, the most common form of dementia, is related to vascular blockage. But dementia has multiple causes, with both genetic and environmental factors at work. Many dementia patients we see in practice begin with insomnia, anxiety, and declining memory. Therefore, if we can comprehensively treat these symptoms early in the elderly, theoretically we can slow brain aging, extend life, and improve quality of life.