Abstract

Cerebral atrophy is a common feature of many of the diseases that affect the brain. Atrophy of any tissue means a decrement in the size of the cell, which can be due to progressive loss of cytoplasmic proteins. In brain tissue, atrophy describes a loss of neurons and the connections between them. Atrophy can be generalized, which means that all of the brain has shrunk; or it can be focal, affecting only a limited area of the brain and resulting in a decrease of the functions that area of the brain controls. If the cerebral hemispheres (the two lobes of the brain that form the cerebrum) are affected, conscious thought and voluntary processes may be impaired.

Some degree of cerebral shrinkage occurs naturally with age; after the brain completes growth and attains its maximum mass at around age 25, it gradually loses mass with each decade of life, although the rate of loss is comparatively tiny until the age of 60, when approximately .5 to 1% of brain volume is lost per year. By age 75, the brain is an average of 15% smaller than it was at 25. Some areas of the brain such as short-term memory are affected more than others and men lose more brain mass overall than women.

Brain atrophy does not affect all regions with the same intensity as shown by neuroimaging.

Symptoms

Many diseases that cause cerebral atrophy are associated with dementia, seizures, and a group of language disorders called the aphasias. Dementia is characterized by a progressive impairment of memory and intellectual function that is severe enough to interfere with social and work skills. Memory, orientation, abstraction, ability to learn, visual-spatial perception, and higher executive functions such as planning, organizing and sequencing may also be impaired. Seizures can take different forms, appearing as disorientation, strange repetitive movements, loss of consciousness, or convulsions. Aphasias are a group of disorders characterized by disturbances in speaking and understanding language. Receptive aphasia causes impaired comprehension. Expressive aphasia is reflected in odd choices of words, the use of partial phrases, disjointed clauses, and incomplete sentences.

Possible causes

The pattern and rate of progression of cerebral atrophy depends on the disease involved.

Possible causes | Infections

Where an infectious agent or the inflammatory reaction to it destroys neurons and their axons, these include...

- Encephalitis, acute inflammation in the brain

- Neurosyphilis, an infection in the brain or spinal chord

- AIDS, disease of the immune system

Diagnosis | The biomarker Neurofilament light (NFL)

Cerebrospinal fluid (CSF) is a fluid that is found exclusively in the brain and spinal cord that circulates between sections of the brain offering an extra layer of protection. Studies have shown that biomarkers in the CSF and plasma can be tracked for their presence in different parts of the brain—and their presence can tell us about cerebral atrophy. One study took advantage of biomarkers, namely one called Neurofilamant light (NFL), in patients with Alzheimer’s Disease. NFL is a protein that is important in the growth and branching of neurons—cells found in the brain. In Alzheimer’s Disease neurons will stop working or die in a process called neurodegeneration. By tracking NFL, researchers can see this neurodegeneration, which this study showed was associated with brain atrophy and later cognitive decline in Alzheimer's patients. Other biomarkers like Ng—a protein important in long-term potentiation and memory—have been tracked for their associations with brain atrophy as well, but NFL had the greatest association.

Diagnosis | Measures

CT and MRI are most commonly used to observe the brain for cerebral atrophy. A CT scan takes cross sectional images of the brain using X-rays, while an MRI uses a magnetic field. With both measures, multiple images can be compared to see if there is a loss in brain volume over time.

Diagnosis | Complications

Cerebral atrophy can be hard to distinguish from hydrocephalus because both cerebral atrophy and hydrocephalus involve an increase in cerebrospinal fluid (CSF) volume. In cerebral atrophy, this increase in CSF volume comes as a result of the decrease in cortical volume. In hydrocephalus, the increase in volume happens due to the CSF itself.

Treatment and prevention

Unfortunately, cerebral atrophy is not usually preventable, however there are steps that can be taken to reduce the risks such as controlling your blood pressure, eating a healthy balanced diet including omega-3's and antioxidants, and staying active mentally, physically, and socially.

Treatment and prevention | Reversibility of cerebral atrophy

While most cerebral atrophy is said to be irreversible there are some recent studies that show this is not always the case. A child who was treated with ACTH originally showed atrophy, but four months after treatment the brain was seemingly normal again.

Chronic alcoholism is known to be associated with cerebral atrophy in addition to motor dysfunction and impairment in higher brain function. Because some of the behavioral deficits have shown improvement after abstinence from alcohol, a study looked to see if cerebral atrophy could be reversed too. Researchers took CT scans of the 8 study participants in order to measure cortical volume over time. Although decrease in atrophy does not equate clinical improvement, the CT scans of 50% of participants showed partial improvement, giving hope that cerebral atrophy could be a reversible process.