Participants will be recruited through established network of Norwegian Memory Clinics. Patients will be randomised to ambroxol with proven effect on the lysosomal and glucocerebrosidase pathology in DLB or placebo. The randomization will be stratified based on APOE e4 and on the concentration of A-beta in CSF. The frequency of GBA genotypes in the active treatment and placebo groups will be calculated at study end. The blinded phase will last for 18 months and an open extension with ambroxol will be offered to all participants for one additional year. The primary outcomes will be cognition, global function, disease stage, progression, and neuropsychiatric symptoms. Secondary outcomes will be on sleep disturbances, falls, fluctuations and parkinsonism, and exploratory outcomes will be impact on the potential biomarkers for drug effects defined as qEEG, DaTSCAN, MRI and α-synuclein in CSF. One hundred seventy-two participants will be recruited in total. Each participant will orally self-administer or administer by a caregiver ambroxol or placebo at 5 intra-participant dose escalations at 60 mg TID (day 1-7), 120 mg TID (day 8- 14), 315 BID (day 15-21), 315 mg TID (day 22-28) and 420 mg TID (day 29-550)).Participants will be subjected to clinical and laboratory assessments to assess the safety, tolerability effects of ambroxol on blood biomarkers and MRI, DaTSCAN, ECG, EEG and lumbar puncture. Each participant will undergo 8 hospital visits and 16 telephone visits for the blinded phase of the study during the first 18 months. Hospital visits will additionally include 1 or 2 screening appointments within 60 days of Day 1 hospital visit (at which participants will receive the first dose of ambroxol), followed by visits at week 4, week 8, week 24, week 36, week 52, month 15 and month 18. Participants will receive a telephone call 3 days after lumbar puncture to record any complaints. Participants will receive 16 telephone calls to record any drug related adverse events in between hospital visits, between 1-3 days before and after each dose escalation (day 1, 8, 15, 22 and 29, week 12,16, 20, 28, 32, 40, 44, 48 and month 13, 14, 16 and 17). All participants will be offered treatment with the IMP for 12 additional months from month 18 - month 30.
This is a confirmatory investigational medicinal product (IMP) study to investigate the effects on cognition, functional decline and on neuropsychiatric symptoms of the Glucocerebrosidase (GCase) enhancing chaperone ambroxol in participants diagnosed with prodromal and early dementia with Lewybodies (DLB).