A new study from the Karolinska Institutet in Sweden suggests that cholinesterase inhibitors (ChEIs), commonly used to manage Alzheimer's disease symptoms, may also hold promise for treating cognitive decline in Lewy body dementia (LBD). The meta-analysis, which examined data from 1,095 individuals with dementia, found that certain ChEIs, particularly donepezil and galantamine, showed potential in reducing the effects of cognitive decline in LBD patients.
The research, which analyzed data from online health registries between 2007 and 2018, focused on individuals who began treatment with ChEIs and memantine within three months of being diagnosed with dementia. The study aimed to assess the effectiveness of these drugs in managing LBD symptoms and slowing cognitive decline.
Key Findings on Cholinesterase Inhibitors
The study revealed that donepezil (Aricept) and galantamine (Razadyne), both cholinesterase inhibitors, demonstrated the most significant potential in reducing cognitive decline over a five-year period. These drugs work by preventing the breakdown of acetylcholine, a neurotransmitter crucial for learning and memory.
Interestingly, rivastigmine (Exelon), another ChEI, did not show as much impact on cognitive decline. However, it exhibited the most significant beneficial effect in reducing mortality risk after a one-year follow-up. This is a noteworthy finding, considering the challenges in diagnosing LBD, which is sometimes only discovered post-mortem.
The researchers also observed that higher doses of ChEIs correlated with greater cognitive benefits. In contrast, memantine, another drug often used in dementia treatment, did not show significant cognitive effects in the context of LBD.
Dosage Considerations and Study Caveats
The meta-analysis considered various studies on ChEIs and focused on patients with LBD who initiated ChEI treatment within three months of diagnosis, adhering to a defined daily dosage rule established by the World Health Organization. One potential reason for rivastigmine's lack of impact on cognitive improvement could be that many patients did not reach the necessary dose for efficacy.
Dr. Maria Eriksdotter, a co-author of the study, noted that older individuals, those living alone, and those with prescriptions for hypnotics, antipsychotics, and antidepressants were less likely to receive higher doses of ChEIs. This suggests that some patients were undergoing different treatments for the disease and possibly other medical conditions, which could influence the outcomes.
Implications and Future Directions
While the study offers promising insights, neurologist Dr. Andrew Larner emphasized that ChEIs are purely symptomatic treatments and do not modify the disease course of LBD or Alzheimer's disease. He also cautioned that the criteria for assessing a reduced rate of cognitive decline can be influenced by the drug approval process.
The study itself acknowledges the lack of approved treatments for LBD worldwide, except in Japan, and notes the unsuccessful attempts in clinical trials for disease-modifying therapies. Most symptom-modifying treatments are currently prescribed off-label.
Further research and long-term monitoring are essential to fully understand the effects of ChEIs on LBD and to develop more effective treatments that can improve the quality of life for patients and their families.
