From the Guidelines
Asymmetric brain atrophy is primarily caused by neurodegenerative diseases, cerebrovascular disease, traumatic brain injuries, inflammatory conditions, developmental disorders, and genetic factors, as supported by the most recent evidence from 1. The primary causes of asymmetric brain atrophy include:
- Neurodegenerative diseases like frontotemporal dementia, corticobasal degeneration, and Alzheimer's disease with focal variants
- Cerebrovascular disease, which can cause asymmetric atrophy through strokes or chronic small vessel disease that affects one hemisphere more than the other
- Traumatic brain injuries, which may lead to focal damage and subsequent asymmetric tissue loss, as discussed in 1
- Inflammatory conditions such as multiple sclerosis, autoimmune encephalitis, and chronic infections like herpes encephalitis, which can trigger regional inflammation and asymmetric neurodegeneration
- Developmental disorders including hemimegalencephaly and Sturge-Weber syndrome, which can cause asymmetric brain development from birth
- Certain seizure disorders, particularly those causing unilateral hippocampal sclerosis, which may result in asymmetric temporal lobe atrophy
- Genetic factors, which can predispose individuals to asymmetric neurodegeneration, especially in conditions with genetic components like frontotemporal dementia Early diagnosis through neuroimaging (MRI, CT) is crucial for proper management, as treatment depends on the underlying cause and may include disease-modifying medications, anti-inflammatory treatments, seizure control, or supportive therapies to manage symptoms and slow progression, as recommended in 1 and 1. Additionally, lifestyle factors such as physical activity, alcohol intake, and cigarette smoking can influence estimates of brain volume and contribute to brain atrophy, as noted in 1. It is essential to consider these factors and the underlying cause of asymmetric brain atrophy to provide appropriate treatment and improve patient outcomes, with a focus on minimizing morbidity, mortality, and maximizing quality of life.
From the Research
Causes of Asymmetric Brain Atrophy
- Asymmetric cortical degenerative syndromes (ACDSs) refer to brain afflictions that result in selective atrophy, particularly with an asymmetric pattern 2
- Alzheimer's disease can cause asymmetric cerebral atrophy, with one hemisphere being more severely affected than the other, consistent with the earliest clinical signs of focal brain damage 3
- Frontotemporal dementia (FTD) is a diverse group of clinical neurodegenerative syndromes characterized by progressive changes in behavior, personality, executive function, language, and motor function, which can also lead to asymmetric brain atrophy 4
- Magnetic resonance imaging (MRI) can be used to differentiate between FTD and Alzheimer's disease based on distinct brain atrophy patterns, with the frontotemporal dementia index (FTDI) showing excellent accuracy in identifying FTD from AD 5
- Certain pharmacological responses, such as lorazepam and quetiapine, can have differential benefits for catatonia-like signs in frontotemporal dementia, suggesting possible relationships between catatonoid signs and insufficient or excessive receptor stimulation 6