Genomics, the mind and the intestine

reference

han cj, Kohen r, jun s, et al. COMT VAL158 MET Polymorphism and improvement in symptoms after a cognitively focused intervention for irritable bowel syndrome. only res . 2017; 66 (2): 75-84.

draft

Secondary genomic analysis of 2 previous randomized controlled studies to compare a package of cognitive behavioral therapy (CBT) by nurses with the usual treatment of irritable bowel syndrome (IBS)

participant

A total of 172 participants (from 2 earlier studies), in which IBS was diagnosed and for the catechol- methyltransferase ( COMT) data were available. The sample was 87 % female; 29 % of the participants had IBS with predominantly constipation, 54 % had IBS with a predominant diarrhea, 11 % had a mixed appearance and 6 % had an unknown IBS Subtype.

study parameters evaluated

ibs symptoms, mental stress, quality of life and cognitive beliefs about IBS

Intervention

IBS-focused CBT package provided by nurses. This included self-work on a CBT for IBS workbook 1 and check-in for nurses for 8 to 9 sessions (60-minute meetings) over 10 to 12 weeks. The concepts treated included the recognition of dietary triggers, relaxation techniques, problem solving, correcting false beliefs, creating pain and practicing good sleeping habits.

primary result measurements

Percentage of the days with moderate to severe abdominal pain or complaints, depression, anxiety and feelings of stress; Secondary measurements included daily gastrointestinal symptoms, letter symptom inventory (retrospective assessment of psychological stress), IBS-QOL scale (quality of life) and cognitive scale for functional intestinal disorders (cognitive beliefs about IBS).

The symptoms were measured 1 month before the start of the course, with reviews 3 and 6 months after the start of the course.

important knowledge

The researchers found out COMT status was statistically significantly associated with the benefit from the CBT package. In particular, after 3 months, those with at least 1 copy of the VAL 158 Met version of the Single Nucleotide Polymorphism (SNP) saw a stronger improvement in their anxiety, their stress, their bloated stomach, its constipation and their retrospective psychological stress. This effect was not observed in the 6-month mark.

practice implications

Katechol- Ö -methyltransferase (COMT) is an important enzyme that is involved in reducing the neurotransmitter dopamine and adrenaline. VAL 158 is a common comment variant, a single nucleotide polymorphism (SNP), in which the different allele for methionine codes ^{th amino acid position instead of valin. This leads to a functional difference in the COMT enzyme, which leads to a drop in enzymatic activity by 30 %. 2 The own status CONT Allele (wild type or variant) was previously associated with the effectiveness of CBT intervention.}

The researchers found that the COMT status was statistically significantly associated with the benefit of the CBT package.

Genetic medicine has come under criticism 5 for the generally minimal clinical effects of individual SNPs. For this reason, many genetic medicine now turns to genetic risk values ​​that consist of a portfolio of SNPs. ⁶ However, CONT is an exception in that it is often still considered and because of its connection with the dopamine levels, is often taken into account in psychological interventions.

Two earlier studies have shown that a cognitive behavioral therapy (CBT) carried out by nursing staff is effective in irritable bowel syndrome. ^{7.8 but the question remained: Do you have the effect of this CBT approach in patients with IBS?}

In this article, the authors found that a CBT package program for IBS was effective compared to the usual treatment and was most effective in patients with at least one valel of the common VAL 158 CONT SNP. The current study showed that this allele is strongest with the improvement of fear and stress, bloating, constipation and subsequent psychological stress.

In general, this was a well -carried out study. It is registered on the website of the US National Library of Medicine Clinicaltrials.gov, which reduces the risk of distorting the selective result reporting. There are also some restrictions on the study. They did not use standard IBS scales, which makes it difficult to understand the extent of the effect, and they only looked at people with a European-American genetic descent. They did this in order to avoid potential distortion problems that are inherent in genomic medical research, but it limits external validity when attempts are made to apply the results to patients with other genetic parentage lines.

As discussed above, the size of the effect modulation is based on CONT The status in this study is difficult to assess, so it can be exaggerated to recommend genetic tests based on this data solely. Nevertheless, I find this study clinically useful. Many of my patients have already identified their comment status by commercially available genetics companies. If I am already considering CBT intervention for an IBS patient because the clinical scenario indicates a strong psychological component, knowing that you have a VAL allel can make my treatment decision. If this is the case, it is easy enough to refer the patient to the workbook that has been used to deliver this special CBT package that is easily available in book and eBook form.

Detailed background to Snps, genomic medicine and a video version of this overview are Available here .