Effects of Hirudotherapy, Phytotherapy, and Forest Therapy in Adults With Reduced Work Capacity or Special Needs

This randomized controlled interventional study will evaluate the biological, functional, and psychosocial effects of complementary and alternative health care services in individuals with a participation level below 55% and/or special needs. The study is designed to generate evidence for the development of standardized, accessible, and evidence-informed protocols for forest therapy, phytotherapy, and hirudotherapy.

A total of 100 participants will be enrolled and allocated to four groups of approximately 25 participants each: a phytotherapy group, a forest therapy group, a hirudotherapy group, and a control group receiving no study-related complementary and alternative health care intervention. Participants in the phytotherapy group will receive three phytotherapy sessions, participants in the forest therapy group will receive ten forest therapy sessions, and participants in the hirudotherapy group will receive six hirudotherapy sessions. The interventions will be delivered by appropriately qualified and licensed practitioners in accordance with Lithuanian legal and professional requirements.

Assessments will be conducted before and after the intervention period. Physiological and functional assessments will include blood pressure, body composition, and handgrip strength. Psychosocial outcomes will include psychological well-being, perceived stress, and sleep quality, assessed using standardized questionnaires, including the WHO-5 Well-Being Index, the 10-item Perceived Stress Scale, and the Pittsburgh Sleep Quality Index. Pre-intervention and post-intervention outcomes will be compared within and between the intervention and control groups.

The study will also evaluate the feasibility, accessibility, safety, and acceptability of providing these services to individuals with reduced participation and/or special needs. Reasonable accommodations may include accessible locations, adapted information formats, assistance with transportation or mobility, and support from accompanying persons when required.

Participant safety will be monitored throughout the study. Eligibility, contraindications, and potential risks will be assessed before the interventions. Any adverse events or unexpected reactions will be documented and evaluated. Particular attention will be given to contraindications and safety requirements associated with phytotherapy and hirudotherapy.

The results will be used to prepare standardized methodological materials and practical recommendations for complementary and alternative health care practitioners, health promotion programs, and social inclusion services.

• Phytotherapy (Other): Participants assigned to the phytotherapy arm will receive three individualized phytotherapy sessions delivered by a qualified complementary and alternative health care practitioner. The intervention may include assessment, selection, and use of legally permitted herbal preparations or herbal products appropriate to the participant's health status and special needs. Products will not be presented as investigational medicinal products. Contraindications, possible interactions, tolerability, and adverse reactions will be assessed and monitored throughout the intervention period.
• Forest Therapy (Behavioral): Participants assigned to the forest therapy arm will receive ten structured forest therapy sessions delivered by a qualified forest therapy practitioner. Sessions will take place in accessible natural or forest environments and may include guided slow walking, sensory awareness, breathing, relaxation, mindful attention, and reflective activities. Session content and pace will be adapted to participants' functional abilities and special needs. Attendance, tolerability, and any adverse events will be documented.
• Hirudotherapy (Procedure): Participants assigned to the hirudotherapy arm will receive six hirudotherapy sessions delivered by a qualified and licensed practitioner. Before the intervention, eligibility and contraindications will be assessed. Medicinal leeches will be applied according to an individualized protocol, taking into account the participant's health condition and safety requirements. Participants will be monitored for bleeding, local skin reactions, infection, allergic reactions, and other adverse events during and after each session.

Primary outcomes

• Change in Systolic Blood Pressure [Baseline and after completion of the intervention period, approximately 3 months after baseline]: Change in resting systolic blood pressure from baseline to the post-intervention assessment. Blood pressure will be measured in millimeters of mercury (mmHg) using a standardized procedure. A lower post-intervention value compared with baseline will indicate a reduction in systolic blood pressure.
• Change in Diastolic Blood Pressure [Baseline and after completion of the intervention period, approximately 3 months after baseline]: Change in resting diastolic blood pressure from baseline to the post-intervention assessment. Blood pressure will be measured in millimeters of mercury (mmHg) using a standardized procedure. A lower post-intervention value compared with baseline will indicate a reduction in diastolic blood pressure.

Secondary outcomes

• Change in Psychological Well-Being Assessed With the WHO-5 Well-Being Index [Baseline and after completion of the intervention period, approximately 3 months after baseline]: Change in psychological well-being from baseline to the post-intervention assessment, measured using the 5-item World Health Organization Well-Being Index (WHO-5). The raw score ranges from 0 to 25, with higher scores indicating better psychological well-being. The raw score may also be multiplied by 4 to obtain a percentage score ranging from 0 to 100.
• Change in Perceived Stress Assessed With the PSS-10 [Baseline and after completion of the intervention period, approximately 3 months after baseline]: Change in perceived stress from baseline to the post-intervention assessment, measured using the 10-item Perceived Stress Scale (PSS-10). The total score ranges from 0 to 40, with higher scores indicating greater perceived stress.
• Change in Sleep Quality Assessed With the Pittsburgh Sleep Quality Index [Baseline and after completion of the intervention period, approximately 3 months after baseline]: Change in sleep quality from baseline to the post-intervention assessment, measured using the Pittsburgh Sleep Quality Index (PSQI). The global score ranges from 0 to 21, with higher scores indicating poorer sleep quality.
• Change in Handgrip Strength [Baseline and after completion of the intervention period, approximately 3 months after baseline]: Change in maximal handgrip strength from baseline to the post-intervention assessment. Handgrip strength will be measured in kilograms using a hand dynamometer under standardized testing conditions. Higher values indicate greater grip strength.
• Change in Body Fat Percentage [Baseline and after completion of the intervention period, approximately 3 months after baseline]: Change in body fat percentage from baseline to the post-intervention assessment, measured using a standardized body composition analyzer. Lower or higher values will be interpreted according to the participant's individual health status.
• Change in Body Weight [Baseline and after completion of the intervention period, approximately 3 months after baseline]: Change in body weight from baseline to the post-intervention assessment. Body weight will be measured in kilograms using a standardized body composition analyzer, with participants assessed under comparable measurement conditions.
• Change in Body Mass Index [Baseline and after completion of the intervention period, approximately 3 months after baseline]: Change in body mass index from baseline to the post-intervention assessment. Body mass index will be calculated as body weight in kilograms divided by height in meters squared and reported in kg/m².
• Change in Skeletal Muscle Mass [Baseline and after completion of the intervention period, approximately 3 months after baseline]: Change in skeletal muscle mass from baseline to the post-intervention assessment. Skeletal muscle mass will be estimated in kilograms using a standardized bioelectrical impedance body composition analyzer under comparable measurement conditions.
• Change in Visceral Fat Level [Baseline and after completion of the intervention period, approximately 3 months after baseline]: Change in visceral fat level from baseline to the post-intervention assessment. Visceral fat will be estimated using a standardized bioelectrical impedance body composition analyzer and reported according to the device-specific visceral fat rating scale. Lower scores indicate a lower estimated level of visceral fat.

Sex: All

Inclusion Criteria:

Individuals with a participation level below 55% and/or officially recognized special needs.

Ability and willingness to participate in the study procedures and assigned intervention.

Provision of written informed consent by the participant or, where applicable, by a legally authorized representative.

Ability to complete the planned assessments independently or with reasonable assistance.

Medical condition sufficiently stable to participate in the assigned complementary and alternative health care intervention.

Willingness to attend baseline and post-intervention assessments and the scheduled intervention sessions.

Exclusion Criteria:

Acute illness, fever, active infection, or clinically unstable health condition at the time of enrollment.

Any medical condition that, in the investigator's or intervention provider's judgment, would make participation unsafe.

Known contraindication to the intervention to which the participant may be assigned.

Current participation in another interventional study that could affect the study outcomes.

Inability to provide informed consent and absence of a legally authorized representative.

Inability to comply with the study procedures or intervention schedule despite reasonable accommodations.

Planned major medical procedure or substantial change in treatment during the study period that could influence the study outcomes.

Additional intervention-specific exclusion criteria:

Phytotherapy: known allergy or hypersensitivity to the planned herbal products; clinically relevant interactions with current medications; pregnancy or breastfeeding, when relevant to the selected herbal product; severe hepatic or renal impairment where the planned preparation may be contraindicated.

Hirudotherapy: bleeding disorders; clinically significant anemia; current anticoagulant or antiplatelet therapy when considered unsafe by the treating clinician; immunodeficiency; active skin infection or lesion at the planned application site; known allergy to leech-related substances; other contraindications identified by the licensed hirudotherapy practitioner.

Forest therapy: acute condition limiting safe participation outdoors; uncontrolled cardiovascular or respiratory symptoms; severe mobility, cognitive, behavioral, or sensory limitations that cannot be safely accommodated; severe allergy or environmental sensitivity relevant to the planned setting.

\-

• Results publication: Siah CJR, Goh YS, Lee J, Poon SN, Ow Yong JQY, Tam WW. The effects of forest bathing on psychological well-being: A systematic review and meta-analysis. Int J Ment Health Nurs. 2023 Aug;32(4):1038-1054. doi: 10.1111/inm.13131. Epub 2023 Mar 2. PMID 36864583
• Results publication: Qiu Q, Yang L, He M, Gao W, Mar H, Li J, Wang G. The Effects of Forest Therapy on the Blood Pressure and Salivary Cortisol Levels of Urban Residents: A Meta-Analysis. Int J Environ Res Public Health. 2022 Dec 27;20(1):458. doi: 10.3390/ijerph20010458. PMID 36612777
• Results publication: Hosseini M, Jadidi A, Derakhshan Barjoei MM, Salehi M. Applications of leech therapy in medicine: a systematic review. Front Med (Lausanne). 2024 Sep 16;11:1417041. doi: 10.3389/fmed.2024.1417041. eCollection 2024. PMID 39351007
• Results publication: Lauche R, Cramer H, Langhorst J, Dobos G. A systematic review and meta-analysis of medical leech therapy for osteoarthritis of the knee. Clin J Pain. 2014 Jan;30(1):63-72. doi: 10.1097/AJP.0b013e31828440ce. PMID 23446069

• Laura Zaliene, PhD, Principal investigator, Klaipėda University