Volume 2, Issue 1, April 2015, Pages 38–48
Special Issue: Integrative Mental Health
Anxiety disorders are the most prevalent group of mental health disorders. Having anxiety has been found to predict the use of CAM (including herbal medicines), and anxiety has been identified as one of the most common health problems treated with CAM. This review aims to: determine the prevalence rates of herbal medicine use in adults experiencing anxiety, and to identify and critically discuss the beliefs and attitudes that predict herbal medicine use in this cohort.
A critical literature review was conducted. Studies that met the inclusion criteria were identified with a comprehensive search across a range of databases.
Eight studies were found across four countries reporting the prevalence of herbal medicine use in people experiencing anxiety — use ranged from 2.39% to 22%. No studies were found that explored attitudes and beliefs as predictors of herbal medicine use in adults with anxiety specifically. Therefore, the criteria were expanded to include other cohorts. Seventeen cross-sectional studies were found, with only one of the studies measuring herbal medicine use specifically, and the remaining studies measuring herbal medicine use within the umbrella of CAM. Three main categories of beliefs and attitudes were identified: belief systems/philosophies, treatment beliefs and attitudes, and control and empowerment beliefs and attitudes.
Herbal medicines are being used to treat anxiety symptoms to varying degrees, with people experiencing worse anxiety symptoms using more herbal medicines. Future research on herbal medicine prevalence in adults with anxiety needs to be valid and comparable using standardized definitions and measures. It is hypothesized that personal control over health, satisfaction with the medical encounter and treatment outcome may be important predictors of herbal medicine use in adults with anxiety, and may help explain why those with more severe anxiety are using more herbal medicines. This is an important area for future research.
- Anxiety disorders;
- Complementary medicine;
- Herbal medicine;
What is already known about this topic?
- Adults with anxiety are using herbal medicines
- Beliefs and attitudes involved in complementary medicine use have been identified
What this paper adds?
- Identifies and critically discusses the prevalence rates of herbal medicine use in adults with anxiety
- Critically discusses the beliefs and attitudes that predict herbal medicine use
- Provides a hypothesis of herbal medicine use behavior in adults with anxiety
Anxiety disorders are the most prevalent group of mental health disorders. In Western countries lifetime prevalence is high; for example, 33.7% in the United States (US) , and 26.3% in Australia  and . In addition, it is not uncommon for people to experience problematic anxiety symptoms, without having an anxiety disorder diagnosis. Individuals not meeting diagnostic criteria for generalized anxiety disorder (GAD) are referred to as having “subthreshold anxiety”  and , and are not reported in prevalence rates. Despite the prevalence of anxiety, people can have dissatisfaction with, or an unwillingness to have, conventional psychological or pharmaceutical treatments  and . Therefore, other treatments are needed that complement conventional treatments, or provide an alternative, such as herbal medicines.
Herbal medicine is known to be the oldest form of medicine, and use is widespread throughout the world. These medicines have a history of being used for a range of physical and mental health problems, including “nervous conditions” . Modern herbal medicine has changed enormously from its traditional roots, with herbal medicines now sold as commercial products that are widely available to the public as over-the-counter supplements . In Western countries the use of herbal medicines has steadily increased since the early 1990s, as products are widely available in retail outlets, and from herbal medicine practitioners. Recent lifetime prevalence rates of herbal medicine use in Western countries have been reported at approximately 31% in the UK , 37% in Australia , and 25% in the US . Herbal medicines are distinguished from conventional pharmaceutical medicines by the use of whole plant parts and not their isolated constituents . They are used as teas, liquid extracts, tablets, capsules, and creams. Herbal medicines are considered to be complementary and alternative medicines (CAMs) not usually part of mainstream health care in Western cultures.
While there is documented traditional evidence for the use of herbal medicines for treating anxiety symptoms, there is a lack of evidence of efficacy from modern research. A number of herbal medicines have shown promising results in both preclinical research (animal models) for relieving anxiety-like symptoms , and in clinical trials . The herb kava (Piper methysticum) is the only herb to date demonstrating Level A evidence for the treatment of generalized anxiety . Other herbs such as passionflower (Passiflora incarnata), chamomile (Matricaria recutita), and Rhodiola rosea have demonstrated promising results in clinical trials for reducing anxiety symptoms in specific patient groups — for a comprehensive review see . However, more research is needed on these and other popular herbal medicines to establish their efficacy in reducing anxiety symptoms generally, and in specific anxiety disorders. Despite the lack of evidence of efficacy people are using these medicines to treat their anxiety symptoms ,  and . Having anxiety has been found to predict the use of CAM (including herbal medicines), and anxiety has been identified as one of the most common health problems treated with CAM .
As there is insufficient evidence for the efficacy of herbal anxiolytics, and people are using them to treat anxiety symptoms, it is important to understand what influences a person's intention to use these medicines. An understanding of the beliefs and attitudes leading to herbal medicine use in adults with anxiety is needed to inform clinical practice (e.g. guide patient education), and to guide future research (e.g. develop theoretical models of health behavior that seek to understand herbal medicine use). This is important, as herbal medicines may not be the most suitable treatment option. For example, psychological interventions or pharmaceutical treatments may be more effective than herbal medicines in treating specific anxiety disorders. In contrast, there may be situations in which herbal medicines are a suitable treatment option, for example, to avoid unwanted side-effects from pharmaceuticals (e.g. kava in generalized anxiety). Consequently, we need to ensure herbal medicines are used in an appropriate way as people may be using them incorrectly, such as: using a medicine incorrectly for its indications, choosing poor quality products, or self-medicating with possible herb-drug interactions  and .
By critically reviewing the literature it is possible to gain a more in-depth understanding of how adults experiencing anxiety use herbal medicines, and what beliefs and attitudes are involved in their decision-making. While there has been one review investigating beliefs and attitudes toward CAM , no review has discussed the beliefs and attitudes as predictors of herbal medicine use specifically in adults experiencing anxiety. This review has two primary aims: to determine the prevalence rates of herbal medicine use in adults experiencing anxiety, and to identify the beliefs and attitudes that predict herbal medicine use in this cohort. In addition, as this is a critical review it will provide a comprehensive synthesis and analysis of the identified literature, and develop a hypothesis of herbal medicine use behavior in adults with anxiety.
2.1. Literature search strategy
A search of published peer-reviewed articles was conducted by the first author, with two aims: (1) to determine the prevalence of herbal medicine use in adults experiencing anxiety, and (2) to identify the beliefs and attitudes that predict intentions to use herbal medicines, or herbal medicine use behavior in adults with anxiety.
For the first aim the search was limited to between 2000 and April 2015. Reporting more recent prevalence rates is necessary, as general herbal medicine use has been steadily increasing in Western countries making earlier studies irrelevant for the purpose of this article. Search terms used for the first aim were anxiety and herb* medicine* or botanical medicine* or plant medicine* or phytotherapy or complementary medicine* or alternative medicine* and prevalence. The same terms were used for the second aim with the addition of belief* or attitude*, and elimination of prevalence. For the second aim the date range of the search was expanded to between 1990 and April 2015. Databases used for both searches were Medline, ESCOhost, ProQuest, Sciencedirect and Google Scholar. Article titles and abstracts were read to determine relevance to the criteria, and if lacking information the full text was retrieved. Reference lists of all articles meeting the criteria were hand searched to ensure all relevant material was included (see Supplement 1 for the inclusion and exclusion criteria). See Fig. 1 for flow diagram.
For the second aim no studies were found that explored the attitudes and beliefs of adults with anxiety as predictors of herbal medicine use. Therefore, the criteria were expanded to include the general population and other patient groups. Examining other cohorts will provide guidance to inform future research into beliefs and attitudes to herbal medicine use in adults experiencing anxiety. Only one study was found that focused on the beliefs and attitudes of herbal medicine use specifically. Therefore, the inclusion criteria were broadened to include CAM use if herbal medicine use was measured. See Supplement 2 for inclusion and exclusion criteria for the second aim. Seventeen cross-sectional studies met the modified inclusion criteria for aim two. See Fig. 2 for flow diagram.
Illness beliefs were excluded from this review, as the majority of studies were focused on illness beliefs for specific health conditions such as cancer and HIV, and unlikely to be relevant to those experiencing anxiety. As this was not a review of efficacy studies expert judgment (by the first author) was used to assess eligible criteria. The beliefs and attitudes identified were organized into three main thematic categories, which were informed by the literature.