Parkinson’s Drugs Show Promise in Improving Alzheimer’s Symptoms, New Study Reveals

For years, Alzheimer’s disease (AD) has remained a formidable challenge for patients, families, and researchers. One of the most heartbreaking realities for many is the phrase: “There is no cure.” Although several new treatments have emerged over the past few decades, options that tangibly improve memory and cognitive function in daily life remain limited.

But now, a groundbreaking study published in the prestigious journal Alzheimer’s & Dementia has captured scientific and public attention: Drugs commonly used to treat Parkinson’s disease may also improve cognitive function in people with Alzheimer’s. This discovery not only blurs the traditional boundaries between neurodegenerative disease treatments, but it also opens exciting new pathways for Alzheimer’s therapy.


Two Diseases, One Target?
Alzheimer’s and Parkinson’s are two distinct disorders—AD is best known for memory loss, while PD is characterized by movement difficulties. Yet they share a common thread: both are neurodegenerative diseases.

• Alzheimer’s research has largely focused on amyloid plaques and tau tangles in the brain. Treatments often aim to boost the neurotransmitter acetylcholine.
• Parkinson’s is mainly caused by the loss of dopamine-producing neurons in the brain’s substantia nigra, leading to tremors and stiffness. Treatment typically involves restoring dopamine function.

The new study highlights that Alzheimer’s patients also show neuron loss in the substantia nigra—the same region primarily affected in Parkinson’s. This area produces dopamine, a chemical essential not only for movement but also for learning,  attention, and motivation.
In other words, Alzheimer’s may involve a dopamine deficiency that has long been overlooked. To explore this possibility, researchers conducted a systematic review and meta-analysis of clinical trials from 1980 to 2023: 

• 19 randomized controlled trials were included
• 1,408 Alzheimer’s patients participated
• Interventions included MAO-B inhibitors (e.g., selegiline, rasagiline), dopamine  receptor agonists, and reuptake inhibitors
• Outcomes were measured using standard cognitive and memory tests

Key Findings: Dopamine Drugs Show Real Benefits
The results were clear: Dopamine-targeting drugs produced small but significant cognitive improvements in Alzheimer’s patients.

1. Overall Cognitive Improvement

Patients receiving dopamine drugs showed better cognitive outcomes than those on placebo. On the MMSE scale (30-point test), drug groups improved by 0.8–1.2 points on average. This modest gain can make a meaningful difference in helping patients remember what they ate or where they put their keys, preserving bits of independence.

2. MAO-B Inhibitors Stand Out

Among the drugs tested, MAO-B inhibitors showed the strongest effect—nearing a “moderate” level of improvement. These drugs work by preventing dopamine breakdown, thereby raising its levels in the brain. In contrast, dopamine reuptake inhibitors did not show significant benefits, suggesting that not all dopamine drugs work the same way in Alzheimer’s.

3. Memory Improved More Than Overall Cognition
Memory, the core deficit in Alzheimer’s, showed greater improvement than general cognitive function. This means patients may better recall recent events or locate everyday objects, exactly the kind of change families hope for.

4. Good Safety Profile
Most patients tolerated the drugs well. Some experienced mild side effects like insomnia, anxiety, or occasional hallucinations—similar to what is seen in Parkinson’s patients. Medical supervision is still essential.

What This Means for Patients & Families
Can You Use These Drugs Now? No—  not without doctor supervision. Using Parkinson’s drugs for Alzheimer’s is still “off-label” and requires evaluation by a neurologist.

Who Might Benefit?
Future tools like dopamine PET scans or blood biomarkers may help identify candidates. For now, these methods are still in development.

Can They Be Combined with Current Medications?
Early data suggest that MAO-B inhibitors can be used alongside cholinesterase inhibitors (e.g., donepezil) without major conflicts. However, dosage and timing must be carefully managed by a doctor.
What’s Next?
A UK team has already launched a Phase IIb clinical trial (Dopa-AD), planning to enroll 300 early-stage Alzheimer’s patients using biomarker screening. Results are expected in 2027. So far, neither the FDA nor EMA has granted MAO-B inhibitors “Breakthrough  Therapy” status for Alzheimer’s. This is not yet a standard treatment, but it is a highly
promising avenue.

Conclusion: A New Ray of Hope
For families clinging to hope, this research offers something tangible: a new direction rooted in science. These drugs won’t cure Alzheimer’s,  but they may help slow cognitive decline, preserve memory, and grant more moments of clarity. Every small step forward is a step toward light.

Reference:
https://alz-journals.onlinelibrary.wiley.com/doi/10.1002/trc2.70142