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Lemon balm and global cognition: grade C

Limited evidence. Direction: No effect.

C Limited

Educational guidance, not medical advice

Why this grade

Rubric condition met: Older-adult and clinical evidence only; one adequately sized RCT null on its primary outcome is not enough for N

A 96-week trial of 323 older adults with subjective or mild cognitive impairment found no difference from placebo on any cognitive measure, with a single subgroup difference in people without hypertension. A 4-month trial of 42 people with mild to moderate Alzheimer's disease, a clinical population, found better ADAS-cog and CDR scores. Evidence is from older and clinical populations only, with one null and one small positive trial, so C with direction none.

How we grade evidence

Studies this grade rests on

EffectMixedNo effectSize shows participants (n)200020052010201520202025RCTNoguchi-Shinohara 2023, 2023: RCT, n = 323, result not recordedAkhondzadeh 2003, 2003: RCT, n = 42, result not recorded
each study this grade rests on, by publication year and design. Solid: effect versus the comparator; half-filled: mixed; hollow: no effect; dashed: result not recorded yet. Larger marks had more participants.
Show the numbers
StudyYearDesignParticipantsResult
Akhondzadeh 20032003RCT42result not recorded
Noguchi-Shinohara 20232023RCT323result not recorded

Melissa officinalis extract in the treatment of patients with mild to moderate Alzheimer's disease: a double blind, randomised, placebo controlled trial.

Akhondzadeh S, Noroozian M, Mohammadi M. Melissa officinalis extract in the treatment of patients with mild to moderate Alzheimer's disease: a double blind, randomised, placebo controlled trial J Neurol Neurosurg Psychiatry, 2003. PMID 12810768

Result not recorded
Design
Randomized, double-blind, placebo-controlled, multicenter trial, 4 months
Sample
n = 42
Population
People aged 65-80 with mild to moderate Alzheimer's disease (clinical population)
Funding
not stated in the PubMed or Crossref record; full text not read

Effects of Melissa officinalis Extract Containing Rosmarinic Acid on Cognition in Older Adults Without Dementia: A Randomized Controlled Trial.

Noguchi-Shinohara M, Hamaguchi T, Sakai K. Effects of Melissa officinalis Extract Containing Rosmarinic Acid on Cognition in Older Adults Without Dementia: A Randomized Controlled Trial J Alzheimers Dis, 2023. PMID 36502333

Result not recorded
Design
Randomized, double-blind, placebo-controlled trial, 96 weeks
Sample
n = 323
Population
Older adults with subjective or mild cognitive impairment, without dementia
Funding
not stated in the PubMed or Crossref record; full text not read

Search and history

Search (): (melissa[ti] OR "lemon balm"[ti]) AND (cognitive[tiab] OR memory[tiab] OR cognition[tiab]) AND (trial[tiab] OR randomized[tiab] OR placebo[tiab])

  • Graded C (proposed): Proposed in the monograph draft
  • C to C (approved): Editor sign-off November 13, 2026: grade matches the editor-approved final page