Rhodiola

Rhodiola is an adaptogen that affects stress systems and several neurotransmitters (norepinephrine, dopamine, serotonin) and has antioxidant / HPA-axis modulating effects. Those actions can improve mental fatigue, sustained attention, processing speed and executive performance — symptoms that overlap with ADHD (especially inattention/fatigue domains). However, that is mechanistic plausibility and clinical trials specifically in ADHD are sparse.

Key mechanistic points:

• Monoamine modulation. Rhodiola and its active constituents (rosavin, salidroside) have been shown in preclinical and some human studies to influence dopamine, norepinephrine and serotonin systems — neurotransmitters central to ADHD. MDPI
• MAO inhibition & neurotransmitter reuptake effects. Some reports show Rhodiola extracts inhibit MAO-A/MAO-B and modulate transporters, which could increase synaptic availability of monoamines (this is one proposed route to improved attention/mood). globalpsychiatry.co.uk
• Adaptogen / stress buffering. Rhodiola modulates the HPA axis and reduces stress-related fatigue — lowering stress and fatigue can indirectly improve attention and executive function. Many clinical studies show benefits on fatigue and “capacity for mental work” under stress. Europe PMC

Important caveat: Most clinical trials demonstrate benefit in stress-related fatigue and mental performance during acute stress/exams/night duty, not classic ADHD. There is very limited direct clinical trial evidence in people formally diagnosed with ADHD (a clinical trial registration for an ADHD study exists, but published results are scarce). Europe PMC

Below are the commonly used formulations/doses and practical points seen in clinical trials and monographs — these are what the published work used, not formal medical prescriptions.

• Common trial doses: clinical studies most often used standardized extracts (SHR-5 or equivalent) in doses ranging from ~170–600 mg/day for chronic dosing, and some single-dose studies used 370–555 mg. A broader reported range across studies is ~200–1,500 mg/day, but most controlled trials for mental performance used ~170–600 mg/day. MDPI
• Standardization: Many clinical trials used a standardized root extract called SHR-5 (specific rosavin:salidroside ratios are used in standardized products). The EMA monograph and clinical reviews discuss using extracts standardized for rosavins and salidroside. European Medicines Agency (EMA)
• How often / timing: Trials used either single doses (morning) or chronic dosing once or split into two daily doses. Because Rhodiola can be stimulating and cause insomnia in some people, it is usually taken in the morning (and avoided late afternoon/evening) in practice and in many guidance documents. MDPI
• Typical starting approach used in practice & by clinicians (informal guidance based on trial ranges):
• Start low: 100–200 mg once daily in morning (standardized extract).
• If tolerated and needed, increase to 200–400 mg/day, taken in morning or split AM/early afternoon. Some trials used 300–600 mg/day.
• Do not take late in day to avoid sleep disturbance. MDPI

Notes / practical points

• Use products standardized for rosavin/salidroside (this improves reproducibility of dosing). The EMA document describes standardized extract composition used in clinical evaluations. European Medicines Agency (EMA)
• Duration in trials: many studies measured effects over 2–12 weeks for chronic trials; acute/single-dose effects on mental work were also reported. If trying for ADHD symptoms, trials for fatigue often saw effects within weeks — but ADHD-specific data are limited. MDPI

What’s well supported

• Randomized controlled trials (RCTs) show benefit for stress-related fatigue and improved “capacity for mental work” (measures of attention, processing speed, memory) in stressed populations (students on exams, physicians on night duty, military cadets). Representative trials:
• Spasov et al., 2000 (pilot RCT) — students during exam period: SHR-5 improved fatigue/stimulation vs placebo. scicompdf.se
• Darbinyan et al., 2000 (cross-over RCT) — physicians on night duty: 170 mg SHR-5 improved a composite Fatigue Index (attention, perception, short-term memory). ScienceDirect
• Olsson et al., 2009 / 2010 — randomized, double-blind, placebo-controlled parallel group trial — SHR-5 improved stress-related fatigue measures. (Planta Medica / Phytomedicine series). Europe PMC
• Systematic reviews / meta-analyses conclude Rhodiola shows promise for mental and physical fatigue and stress-related symptoms, but caution that study sizes are small and heterogeneity exists. Example: systematic review of RCTs for fatigue found benefit but flagged limited quality and small sample sizes. Europe PMC

What is not proven

• Direct, robust RCT evidence in diagnosed ADHD is lacking. There is a clinical trial registration for Rhodiola in adults with ADHD (NCT02737033) but published peer-reviewed results specific to ADHD diagnosis are not widely available. Therefore, we cannot say Rhodiola is an established ADHD treatment based on current RCT evidence. ICHGCP

Representative review articles (mechanism + clinical data):

• Panossian & Wikman — comprehensive review of traditional use, composition, pharmacology and clinical efficacy (Phytomedicine). Good for mechanism and trial summaries. ScienceDirect
• MDPI (2022/2023) and other recent reviews summarize clinical trial data and note promising results for fatigue/stress and cognitive endpoints, while calling for higher-quality trials for other indications. MDPI