D-SPARK: A Clinical Trial of D-Serine for Modifying Parkinson's Disease Progression

Recruiting now · Phase 2 · Has a placebo group

Conditions studied: Parkinson s Disease, Parkinson Disease (PD)

In brief

This clinical study, designed as a randomized, double-blind, placebo-controlled trial, aims to investigate if modulation of the N-methyl-D-aspartate receptor (NMDAR) via its co-agonist D-serine has therapeutic benefits in Parkinson's disease (PD). All patients will receive both placebo and D-serine over different time periods during the study. Preclinical studies have shown that blocking glycine transporters, which elevates endogenous glycine levels, can restore NMDAR function and improve motor deficits in PD models. A clinical trial demonstrated that oral D-serine (30 mg/kg/day for 6 weeks) significantly reduced extrapyramidal and abnormal involuntary movements in PD patients compared to placebo, with improvements observed in both motor and non-motor symptoms. D-serine supplementation has shown an acceptable safety profile with doses up to 120 mg/kg showing no significant adverse effects in clinical studies. The D-SPARK trial primarily aims to determine the efficacy of D-serine supplementation on clinical severity of PD as measured by the Movement Disorder Society Unified Parkinson's Disease Rating Scale (MDS-UPDRS). Secondary aims are to determine the efficacy of D-serine supplementation on improving dopaminergic nigrostriatal innervation as measured by single-photon emission tomography (SPECT) based imaging of the dopamine transporter (DaT-scan) and cognition as measured by the California Verbal Learning Test version 2 (CLVT-II). The study will include 100 persons with Parkinson's disease (PwPD) diagnosed no longer than 5 years before baseline. Participants will be randomly assigned to receive D-Serine 4000 mg daily or placebo for defined periods of time during a 58 week treatment period, followed by a 12 week washout period. Participants will undergo: * Clinical evaluations, including clinical rating scales and questionnaires. * Cognitive assessments. * Bio sampling of whole blood and blood plasma. * Single-photon emission tomography (SPECT) imaging of dopamine transporter levels (DaT-scan) The outcomes of this study could potentially demonstrate that D-serine reduces symptom severity in Parkinson's disease and/or has an impact on the clinical trajectory of Parkinson's disease, benefiting persons living with Parkinson's disease, their families and society as a whole.

Key facts

Study ID

NCT07312110

Run by

Haukeland University Hospital

People needed

100

Starts

2026-01-20

Expected to finish

2028-12-01

Last updated by the study team

2026-06-04

Who can join

Age: 40 and older, up to 80. Sex: any. Healthy volunteers: not accepted.

You may qualify if…

• A clinical diagnosis of PD* according to the clinically established MDS clinical diagnostic criteria for Parkinson's disease within 5 years.
• [¹²³I]FP-CIT single photon emission CT (DaTscan) confirming dopaminergic nigrostriatal denervation.
• Hoehn and Yahr score < 3 at enrollment.
• Optimal symptomatic PD treatment, not requiring adjustments, for at least 2 weeks.
• Age ≥40 and ≤ 80 years at time of enrollment.

You may not qualify if…

• Dementia or neurodegenerative disorder other than PD at baseline visit.
• Atypical parkinsonism (PSP, MSA, CBD vascular parkinsonism, or drug induced parkinsonism).
• Any known monogenic cause of PD (GBA1 variation is accepted).
• Any psychiatric disorder that would interfere with compliance in the study.
• Any severe somatic illness that would make the individual unable to comply and participate in the study.
• Use of D-serine supplementation within 90 days of enrolment.
• Metabolic, neoplastic, or other physically or mentally debilitating disorder at baseline visit.
• Active of planned pregnancy during trial period.
• Cognitive impairment as measured by the Mini Mental Status Exam MMSE) < 20.
• Weight < 45 kg.
• Urinary albumin/creatinine ratio ≥ 20 mg/mmol at time of enrollment.
• Participants will be excluded if they have CKD stage 3 or higher, defined as:
• Estimated golumerular filtration rate (eGFR) < 60 mL/min/1.73min\^2 at screening, calculated using the CKD-EPI 2021 creatinine equation.

Where it is running

• Nevro Arendal Soerlandsklinikken — Arendal, Agder, Norway (enrolling)
• Oslo University Hospital — Oslo, Oslo, Norway (enrolling)
• Haukeland University Hospital — Bergen, Vestland, Norway (enrolling)
• Molde Hospital — Molde, Møre og Romsdal, Norway
• Bodø Hospital (Nordland Hospital) — Bodø, Nordland, Norway
• Førde Hospital — Førde, Vestland, Norway
• Haugesund Hospital — Haugesund, Rogaland, Norway
• University Hospital of North Norway — Tromsø, Troms, Norway
• Østfold Hospital — Sarpsborg, Østfold fylke, Norway
• Akershus University Hospital — Lørenskog, Akershus, Norway
• Vestre Viken Hospital — Drammen, Buskerud, Norway

Full record on ClinicalTrials.gov

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