From the Guidelines
Brain atrophy on imaging indicates a loss of brain tissue volume, which appears as enlarged ventricles, widened sulci, and decreased overall brain mass, and is a marker of neurodegeneration that can suggest several conditions, including normal aging, neurodegenerative diseases, multiple sclerosis, traumatic brain injury, stroke, or chronic alcohol abuse, as noted in a study published in Nature Reviews Neurology 1. The pattern and location of atrophy often helps determine the underlying cause - for example, hippocampal atrophy is characteristic of Alzheimer's disease, while frontotemporal atrophy suggests frontotemporal dementia, as discussed in the Journal of the American College of Radiology 1. Some key points to consider when evaluating brain atrophy include:
- The significance of atrophy depends on its extent, location, and the patient's age and clinical symptoms, with mild atrophy potentially being normal in elderly individuals, while pronounced atrophy in younger patients typically indicates pathology, as noted in Alzheimer's and Dementia 1.
- Brain atrophy occurs when neurons die and their connections deteriorate, leading to tissue loss, a process that is irreversible in most cases, though addressing underlying causes may slow progression, as discussed in Nature Reviews Neurology 1.
- Radiologists typically quantify atrophy by comparing brain volume to age-matched controls or through sequential imaging to track changes over time, with whole brain atrophy over a minimum period of 12 months recommended as a secondary endpoint in clinical trials in MS, as stated in Nature Reviews Neurology 1. The most recent and highest quality study, published in 2025 in Alzheimer's and Dementia 1, provides guidance on the use of brain MRI in the evaluation of Alzheimer's disease and related disorders, highlighting the importance of considering atrophy patterns and location in determining the underlying cause of cognitive impairment. Some important considerations when evaluating brain atrophy include:
- The role of pseudoatrophy, which can occur within the first 6-12 months of treatment initiation with anti-inflammatory therapy, and can be mitigated by re-baseline MRI at 6-12 months after initiation of therapy, as recommended in Nature Reviews Neurology 1.
- The potential use of spinal cord atrophy as a treatment-monitoring tool, which has been scarce but may be improved with methodological advances, as noted in Nature Reviews Neurology 1.
- The importance of considering readily treatable common comorbid conditions, such as infections, dehydration, hypothyroidism, and vitamin B12 deficiency, which can contribute to cognitive or behavioral symptoms and may cause subacute or acute clinical decompensation, as discussed in Alzheimer's and Dementia 1.
From the Research
Brain Atrophy Indications
Atrophy on brain imaging can indicate various conditions, including:
- Progressive loss of brain tissue bulk, which can be detected in vivo by MRI 2
- Irreversible tissue destruction, an important determinant of disease progression in multiple sclerosis 2
- Overall tissue loss, especially demyelination and axonal loss in multiple sclerosis 3
- Damage to whole brain tissue, which explains most of the variance in overall brain volume 3
- Generalized or focal atrophy, occurring in specific brain regions such as the thalamus, hippocampus, and cerebellum 4
- Aging-related structural brain changes, including ventricular enlargement and cortical thinning 5
Clinical Relevance
Brain atrophy has significant clinical implications, including:
- Prediction of disease progression and clinical outcome in multiple sclerosis 2, 6
- Association with cognitive impairment and dementia 5
- Correlation with age and cognitive performance 5
- Potential use in quantifying the impact of dementia on brain structures 5
Measurement and Assessment
Brain atrophy can be measured and assessed using various methods, including: