Study To Evaluate the Efficacy, Safety and Tolerability of E2027 in Participants With Dementia With Lewy Bodies

Inclusion Criteria:

- Male or female, age 50 to 85 years, inclusive at time of consent.

- Meet criteria for probable dementia with Lewy bodies (DLB) (as defined by the 4th
report of the DLB Consortium).

- Mini-Mental State Examination ≥14 and ≤26 at Screening Visit.

- Has experienced visual hallucinations during the past 4 weeks before Screening Visit.

- If receiving acetylcholinesterase inhibitors (AChEI), must have been on a stable dose
for at least 12 weeks before Screening Visit, with no plans for dose adjustment during
the study. Treatment-naive participants can be entered into the study but there should
be no plans to initiate treatment with AChEIs from Screening to the end of the study.

- Must have an identified caregiver or informant who is willing and able to provide
follow-up information on the participant throughout the course of the study.

- Provide written informed consent. If a participant lacks capacity to consent in the
investigator's opinion, the participant's assent should be obtained, as required in
accordance with local laws, regulations and customs, plus the written informed consent
of a legal representative should be obtained (capacity to consent and definition of
legal representative should be determined in accordance with applicable local laws and
regulations). In countries where local laws, regulations, and customs do not permit
participants who lack capacity to consent to participate in this study, they will not
be enrolled.

Exclusion Criteria:

- Any neurological condition that may be contributing to cognitive impairment above and
beyond those caused by the participant's DLB, including any comorbidities detected by
clinical assessment or magnetic resonance imaging (MRI).

- History of transient ischemic attacks or stroke within 12 months of Screening.

- Modified Hachinski Ischemic Scale greater than >4.

- Parkinsonian (extrapyramidal) features with Hoehn and Yahr stage 4 intravenous or
higher.

- Any major psychiatric diagnosis, including schizophrenia, bipolar disorder and current
major depressive disorder as per Diagnostic and Statistical Manual of Mental Disorders
Fifth Edition.

- Geriatric Depression Scale score > 8.