Volume 2, Issue 1, April 2015, Pages 38–48
Special Issue: Integrative Mental Health
Open Access
Abstract
Objective
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.
Method
A
critical literature review was conducted. Studies that met the
inclusion criteria were identified with a comprehensive search across a
range of databases.
Results
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.
Conclusions
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.
Keywords
- Anxiety disorders;
- Attitudes;
- Beliefs;
- Complementary medicine;
- Herbal medicine;
- Prevalence
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
1. Introduction
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) [1], and 26.3% in Australia [1] and [2].
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” [3] and [4],
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 [5] and [6].
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” [7].
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 [8].
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 [9], 37% in Australia [10], and 25% in the US [11].
Herbal medicines are distinguished from conventional pharmaceutical
medicines by the use of whole plant parts and not their isolated
constituents [12].
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 [13], and in clinical trials [14]. The herb kava (Piper methysticum) is the only herb to date demonstrating Level A evidence for the treatment of generalized anxiety [15]. 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 [14].
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 [8], [16] and [17].
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 [18].
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 [16] and [17].
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 [19],
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. Method
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.
- Fig. 1.Flow diagram of studies included in aim one.
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.
- Fig. 2.Flow diagram of studies included in aim two.
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.