Brief internet-based cognitive behavior therapy program with a supplement drink improved anxiety and somatic symptoms in Japanese workers

Recently, evidence-based behavioral healthcare has been provided over the Internet, via computers, tablets, or smartphones. Traditionally, self-help treatment has involved the use of printed manuals or books [1, 2]; however, several Internet and computer-based self-help treatment programs have been developed and tested recently. Internet-based cognitive behavior therapy (ICBT) is a technology-based CBT technique delivered with or without the support of a clinician. The findings of previous meta-analyses indicate that computer-based psychological treatments for depression [3] and anxiety disorders [4] are effective. Furthermore, meta-analyses suggest that self-help CBT is effective for the treatment of low-to-moderately severe psychological problems [5, 6]. Self-help treatments, such as ICBT, can overcome barriers to care such as limited availability of clinicians trained in evidence-based interventions [7]. Moreover, ICBT is effective for patients who are reluctant to seek medical help because of stigma [8]. However, a previous study found that technology-based treatments had a high dropout rate [9].

Previous research suggests that work-related psychological problems are associated with depression and anxiety disorders [10, 11]. The psychophysiological function of workers is affected by increased work pace, more high-skilled jobs, and an increase in the use of information and communication technology [12]. Previous studies suggest that distinct demanding or threatening extrinsic features of job environments and employment conditions may be detrimental to workers’ health and that specific personality traits and coping behaviors may increase workers’ vulnerability to stress [13, 14]. Furthermore, chronic job-related stress has been shown to adversely affect physical and mental health and increase the risk of cardiovascular diseases and impair work performance [15]. Suwazono et al. [16] found that the threshold for working hours associated with fatigue symptoms under the worst job-related stress was very close to the standard daily working hours in Japan. The negative effects of long working hours on subjective fatigue have been documented in Japanese workers [17, 18], highlighting the importance of preventing the development of stress-related psychological problems by reducing work-stress factors.

Several recent studies have examined the effects of web-based CBT programs for employees. Kimura et al. [19] found that a brief CBT-based training program significantly improved subjective work performance. An investigation of the combined effect of brief CBT education with web-based CBT homework in healthy workers found that the program moderately alleviated symptoms in employees with clinically significant psychological distress [20]. These reports suggest that self-help CBT is a moderately effective intervention for a range of common mental health problems in the work place.

Recent research has investigated the effect of consuming food with supplements on health conditions. Some studies have focused on carnosine, which is present in meats such as chicken and beef. Carnosine is immediately absorbed intact in the jejunum, despite being a dipeptide [21]. It is metabolized by the enzyme carnosinase [22] and excreted via the kidneys [21]. Carnosine is decomposed into β-alanine and histidine in the blood, and it is considered to be effective in recovery from fatigue. Carnosine has L-carnosine and D-carnosine. In the present study, we used L-carnosine because it is a natural ingredient, but D-carnosine is not. L-Carnosine is a naturally occurring amino acid found in high concentrations in muscle, heart, and brain tissues. We felt that by conducting research with supplements close to natural ingredients, it would be possible to examine the situation in a manner close to everyday life.

A previous study found that consumption of a drink containing imidazole dipeptides (400 mg) over an 8-week period significantly improved fatigue compared with a placebo [23]. Yamano et al. [24] found that daily intake of a chicken extract that contained large amounts of imidazole dipeptides (carnosine and anserine) promoted recovery from mental fatigue. Anserine (beta-alanyl-1-methyl-L-histidine) is a methylated form of carnosine that is present at high levels in the breast skeletal muscle of chicken. Imidazole dipeptides are natural antioxidants in meat extract. The antioxidant effect of imidazole peptide inhibits tissue damage and suppresses the reduction in performance level induced by mental fatigue. These findings suggest that foods or beverages containing imidazole dipeptides may be used as anti-fatigue supplements [24]. A previous study that examined the effect of computerized CBT, which included both Internet based and off-line software based programs, in combination with a supplement drink containing L-carnosine found that the program improved anxiety and fatigue [25]. In contrast, little is known about the effect on workers of brief self-help ICBT combined with a supplement drink.

Thus, based on previous findings, this study was done to test our hypothesis that the combination of easy-to-implement self-help CBT and supplementation with L-carnosine would improve mental health, in terms of anxiety, depression, and fatigue, in the workplace.

First, we examined the effect of the ICBT program on mood. We used paired t-tests to compare the pre- and post-intervention POMS scores and found a significant improvement in the POMS-TA subscale (t[47] = 2.06, p < .05). However, no significant difference was found for the POMS-D and POMS-F subscales (t[47] = −1.08, p = .28; t[47] = 0.19, p = .85, respectively; Table 2).

We calculated effect size (Cohen’s d) to assess the degree of change in the POMS-TA scores. Cohen [30] categorized effect sizes as small (0.20–0.49), medium (0.50–0.79), and large (0.80 or more). The effect size for the POMS-TA subscale was d = 0.23 (95% confidence interval (CI) = −0.17 to 0.63); thus, according to Cohen’s classifications, the change in POMS-TA scores for the ICBT group was small.

To investigate somatic symptoms, the somatic scores on the BJSQ were assessed using paired t-tests. Low back pain was the only somatic symptom that improved significantly over the course of the program (baseline, 1.83 ± 0.95 vs. post-intervention, 1.56 ± 0.87; p = .03; Table 3).

We conducted a supplemental analysis to compare the POMS-TA scores of participants who did and did not complete the tasks. ANOVA results (Fig. 2) revealed a tendency toward an interaction (F(1, 73) = 2.94, p = .091): the POMS-TA score was significantly improved for the participants who completed the task (p < .05).

We examined the effect of a brief ICBT program administered with a soft drink containing a supplement (L-carnosine) on healthy Japanese workers. The goal of the therapy was to relieve tension and anxiety. Additionally, a supplementary analysis suggested that completing the program tasks significantly improved tension and anxiety, highlighting the importance of compliance.

The effect size of the change in the POMS-TA score was small (d = .23), which is consistent with previous research showing that non-facilitated computerized CBT, which includes both Internet based and off-line software based programs, has a small effect (d = .38) [3]. Our ICBT intervention consisted of video clips, an e-textbook, and a supporting comic strip, available on demand. Although the duration of the intervention was short (4 weeks), the components were accessible and readily understood, and the program reduced tension and anxiety. Furthermore, the supplement drink may have improved the mental state of participants and increased their ability to complete the tasks. The supplement drink has been shown to improve health; moreover, continual consumption of the drink was an indication of the participants’ commitment to the ICBT program.

However, the completion rate of the ICBT program was relatively low. The autonomous self-help nature of the intervention may account for the low completion rate. An e-mail notification was automatically sent to all participants to remind them to complete each task; however, we provided no therapist contact or support staff, which may have decreased the motivation to complete all of the tasks.

Our finding that the intervention did not significantly affect fatigue and depression was not consistent with previous studies suggesting that foods and drinks containing L-carnosine promote recovery from mental fatigue [23, 24]. In a study conducted by Shimizu et al. [23], subjects consumed a supplement drink containing an anti-fatigue agent, imidazole dipeptides, for 8 weeks. The duration of our program was 4 weeks, which may have been too short for the supplement drink to affect fatigue or depression.

With regard to somatic symptoms, participants reported that our program significantly improved low back pain. Previous investigations have found differences in improvement of the anxiety of hypochondriacal patients with and without low back pain [31, 32]. Nakao et al. [31] reported that high anxiety at entry into the CBT program predicted a better treatment outcome for somatic symptoms and health anxiety associated with cognitive-behavioral interventions. The ICBT program improved the anxiety and low back pain of workers. Therefore, it may be that decreased levels of anxiety are related to improved low back pain.

Abbott et al. [33] investigated the effectiveness of an ICBT program for tinnitus distress and failed to find a significant difference in outcome between ICBT and information-only groups. However, the authors noted that the high attrition rate and small sample size, particularly in the intervention group, limited the generalizability of their findings. This highlights the importance of determining why participants drop out of internet-based programs to identify ways to increase motivation and compliance. In fact, we found that the change in the POMS-TA subscale was significant only in the group that completed the tasks, suggesting that high motivation and compliance are the keys to an effective brief ICBT program with a supplement drink.

Our study has several limitations. First, all of the subjects were tested under the same condition, i.e., they all participated in the ICBT program and consumed the supplement drink. Further study including subjects who take the supplement only and a control group will be necessary to clarify the effects of the supplement drink alone and together with ICBT. It is thought that these methods will also control the influence of “the Hawthorne effect”. Also, in this study, since we did not set a group to take a placebo drink, it is indicated as a subject to be studied in the future. Second, the present study took a completely self-help approach with no therapist or support staff contact. It is likely that outside guidance would increase engagement and compliance; thus, the potential effects of therapist support on our ICBT program should be examined. In terms of the dropout rates, the values of the present study were relatively high because of its complete self-help approach. Because our aim was a preliminary examination of the effect of the program tested in this research, we emphasized and analyzed only the data of participants who accomplished all of the tasks. For that purpose, we analyzed and examined only the data of the program completers. As for this point, future research will need to be done with a strict research design and that includes a control group or that uses intention to treat analysis to provide greater clarity. Third, our participants were relatively healthy employees. Future studies are needed to examine the effects of the brief ICBT program on individuals at high risk of mental health problems and those who have mental disorders. Additionally, the participants in the present study included those who belonged to the company that created the supplement drink. The participants may have implicitly reported desirable results, which may have biased the study.

We investigated the effect on psychological well-being of a self-help ICBT program administered with a supplement drink containing L-carnosine. The combined program reduced the subjective experience of anxiety and low back pain in these workers. Future studies are needed to compare multiple groups and to examine the effect of therapist support.