Parkinson's non-motor symptoms reduced with microdoses of THC and CBD
Parkinson's Disease (PD) affects nearly 1 in 40 people over the age of sixty and can be debilitating. There are two major types of symptoms: motor and non-motor. Motor symptoms include resting tremors and rigidity.
Non-motor symptoms can include cognitive impairment, sleep disturbances, autonomic dysfunction, anxiety and depression. This case study focused on non-motor symptoms. It was published in the journal Frontiers in Human Neuroscience in February 2025.
Insomnia has been reported by around 80% of PD patients. It is one of the most difficult non-motor symptoms to consistently alleviate.
6 PD patients participated in this case study. The Hoehn and Yahr scale was used to select only patients in stages III and IV of the 5 stages of Parkinson's Disease. The other criteria for inclusion were age over 40 currently on stable treatment with levodopa for at least 30 days. If a patient suffered from schizophrenia or had a family history of it or psychosis, they were not included. Additionally, they eliminated any patient with a history of cannabis or illegal psychoactive substance use.
The 6 patients included were 4 men and two women ranging in age from 49 to 76, and each was diagnosed with PD at least 5 years previously. None were smokers or drinkers.
The patients were randomly divided into 2 groups with each group given a different daily micro-dose of full-spectrum cannabis extract from a single plant for a period of 90 days:
- 0.25 mg THC + 0.28 mg CBD
- 1.0 mg THC + 0.112 mg CBD
The THC:CBD ratio was about 9:1. All patients were also taking levodopa (200 mg + benserazide 50 mg).
Changes in the non-motor symptoms were assessed using the following scales:
- Montreal Cognitive Assessment test (MoCA)
- Epworth Sleepiness Scale (ESS)
- Insomnia Severity Index (ISI),
Results:
The statistical analysis indicated a significant benefit of the cannabis extract treatment, at dose of 1000:112 μg/day after 60 days of treatment, on insomnia
the statistical analysis of data from ISI and MoCA tests showed a trend toward improvement over time, while no significant effect was observed in the ESS.
[for cognitive improvement] patients who received the lower dose (250:28 μg/day THC:CBD) presented a more marked improvement in comparison to baseline conditions
although the main aim of the current study was to investigate the impact of Cannabis extract treatment on non-motor symptoms, the PD patients reported improvement in their motor symptoms
No self-reports of relevant side effects was mentioned by participants of this study.
The most effective dose for insomnia in PD patients was 1mg THC plus 0.1mg CBD each day. 0.25mg THC plus 0.112 mg CBD showed less improvement for insomnia, but more improvement in cognition. These are considered very small doses for most other accepted uses of medical cannabis treatment.
The cognitive assessment and insomnia severity index showed improvements at all points (15, 30, 60 and 90 days). It's too bad they did not explore slightly larger doses to determine if the improvement trend continued.
Authors' Conclusion:
These results demonstrate benefits of short-time treatment (3 months) with low doses of cannabis extract on cognition and insomnia in PD patients.
The full text paper is here at PubMed Central.
Source:
Ruver-Martins AC, Martinez IAR, Holla VG, de Souza BL, da Silva EG, Novoa DMA, Souza-Silva E, Araujo FS, Prediger RD, do Nascimento FP. Low doses of cannabis extract ameliorate non-motor symptoms of Parkinson's disease patients: a case series. Front Hum Neurosci. 2025 Feb 24;18:1466438. doi: 10.3389/fnhum.2024.1466438. PMID: 40066073; PMCID: PMC11891160.