Biomarkers are important tools that help us understand brain diseases better. They improve how doctors diagnose problems, personalize treatments, and keep track of how diseases progress. Here’s how biomarkers help:

1. Early Diagnosis and Identification:

   • Biomarkers can spot brain diseases even before patients notice any symptoms. For example, certain levels of proteins in spinal fluid, like amyloid-beta and tau, are linked to Alzheimer’s disease. Research shows that people with higher tau levels have a $3.5$ times greater chance of developing Alzheimer’s, even if they seem healthy (Petersen et al., 2019).
   • Doctors also use MRI scans to see structural changes in the brain. These changes can help identify different types of brain diseases early, making it possible to start treatment sooner.

2. Disease Subtyping:

   • Biomarkers help sort diseases into different categories, making diagnoses more accurate. For example, some specific gene changes in amyotrophic lateral sclerosis (ALS) can show whether the disease runs in families or appears randomly. This helps doctors understand the disease better and choose more suitable treatments.

3. Monitoring Disease Progression:

   • Some biomarkers can measure how a disease gets worse over time. In the case of Multiple Sclerosis (MS), MRI results can measure the size of brain lesions. This information helps doctors see how effective the treatments are.

4. Personalized Medicine:

   • Biomarkers allow doctors to customize treatment plans for each patient. For instance, in Parkinson’s disease, specific genetic traits can help guide treatment choices. This personalized approach can improve patient outcomes by up to $30\%$ compared to regular treatments (Goldman et al., 2020).

5. Understanding Mechanisms:

   • Biomarkers can help us learn more about how diseases work. For example, certain markers of inflammation are linked to depression, showing that people with major depressive disorder have higher levels of these markers.

In summary, using biomarkers in studying brain diseases helps doctors diagnose issues faster, choose better treatments, and understand how diseases develop. This greatly improves care for patients with neurological disorders.