Comments on "Serum Lipids among Drug Naïve or Drug-Free Patients with Obsessive Compulsive Disorder and Their Association with Impulsivity".

Vats et al.[1] presented a cross-sectional, comparative study on serum lipids and obsessive compulsive disorder (OCD)-related impulsivity. It is a good attempt to search for a biomarker of impulsivity. However, the study is methodologically flawed in different dimensions that should be discussed before taking any clinical conclusion from it.

Though the sample size was small (N = 40), it is acceptable in a case-control design. The sample was not explored for the metabolic profile, lifestyle factors, pregnancy, or post-pregnancy changes (which is relevant given the higher female to male ratio), neither did the study mention specifics on substance abuse. Does comorbid diagnosis according to International Classification of Diseases, Tenth Revision mean nicotine dependence too? That also should have been specifically mentioned, as having a metabolic syndrome and substance use can have a significant impact on the lipids fraction.[2] Moreover, persons with psychiatric illness have a higher prevalence of metabolic syndrome.[3]

Even though the study speaks about the OCD types, it did not mention OCD symptomatology. For example, a person with severe OCD-related slowness can have a significant sedentary lifestyle that results in dyslipidemia.[4] Hypothetically, an OCD patient can have binge-eating habbits, leading to an increased level of lipids, especially triglycerides.[5]

The impulsivity construct was divided into high and low with an author-made analogy by using the median, although the scoring manual of the Barratt Impulsiveness Scale does not allow it. The authors could have checked the relationship with the use of Pearson or Mann–Whitney tests, without molding the nature of the scale.

The conclusion achieved was a negative correlation between high density cholestrol and impulsivity. There are a few studies that say low HDL can be present in the normal population as well.[6] As the authors did not consider normal controls in correlating impulsivity, the HDL-related finding might be just a normal phenomenon.[7] In the end, the authors did not explain any clinical significance of the study.

We feel that it is a welcome step, being the first study, but more studies with a stringent study design are needed in this area.