Brain neurochemistry in unmedicated obsessive–compulsive disorder patients and effects of 12‐week escitalopram treatment: ¹H‐magnetic resonance spectroscopy study

Abstract

Aim The purpose of this study was to examine treatment‐related neurochemical changes in 28 unmedicated obsessive–compulsive disorder (OCD) patients using 1H‐magnetic resonance spectroscopy (1H‐MRS). Methods We included subjects diagnosed with OCD (n = 28), each with a total duration of illness of less than 5 years, as a study group and age‐ and sex‐matched healthy controls (n = 26). The inclusion criteria for the OCD group were right‐handed individuals aged 18 years or older who had not been on any specific treatment for OCD for the last at least 8 weeks and who had no other psychiatric comorbidity. A pre–post and case–control design was employed in which OCD patients underwent 1H‐MRS at baseline and 12 weeks after treatment with escitalopram (n = 21). Clinical assessment was carried out using a semi‐structured pro forma Yale–Brown Obsessive Compulsive Scale and the World Health Organization Disability Assessment Scale 2.0 before and after treatment. Volume‐localized 1H‐MRS was carried out with a 3‐Tesla Philips MR scanner. Results Our data suggested higher levels of myoinositol (mI), total choline (tCho), and glutamate+glutamine (Glx) in the medial thalamus at pre‐assessment in OCD subjects as compared to healthy controls and a significant reduction in tCho and Glx after treatment in OCD subjects. The mI levels in the caudate nucleus and Glx levels in the anterior cingulate cortex were significantly correlated with disease severity on the Yale–Brown Obsessive Compulsive Scale. Conclusion Our study supports the hypothesis of a hyper‐glutaminergic state (as suggested by increased Glx levels) and neurodegeneration (as suggested by increased tCho and mI in the thalamus) in cortico‐striato‐thalamocortical circuitry in OCD patients as suggested by previous studies using MRS as well as other functional imaging studies.

Correlations Between Working Memory Impairment and Neurometabolites of the Prefrontal Cortex in Drug-Naive Obsessive-Compulsive Disorder

“… 33 Some recent studies on OCD have also found changes in the levels of inositol metabolism in the brain. Parmar et al 38 have found significant increase in inositol levels in the caudate nucleus and anterior cingulate cortex of OCD. It is positively correlated with the compulsive symptoms and disease severity, and it is speculated to be related to the potential reversible abnormalities in regulating the neuro-osmotic pressure.…”

“… 35 , 37 Additionally, a study with the effect of 12-week treatment using citalopram on NAA/Cr ratios in 13 drug-naive patients with OCD showed a significant increase in the bilateral prefrontal cortex, frontal white matter and anterior cingulate when compared to those before treatment. 38 So, the decrease of NAA/Cr ratios in the lPFC might indicate gray matter volume reduction and neuronal damage in OCD, which is closely related to verbal working memory impairment.…”

1H Nuclear Magnetic Resonance: A Future Approach to the Metabolic Profiling of Psychedelics in Human Biofluids?

“…In MRI, water molecules are detected to produce a spatial map of the brain, but for MRS the focus is on detecting metabolite signals in specific brain regions (typical voxel size: 4-8 cm 3 ) (170); these metabolites can be neurotransmitters like glutamate (171)(172)(173) or γ-aminobutyric acid (GABA) (174)(175)(176). The psychopharmacological approach to 1 H MRS involve studies that monitor neurotransmitter changes in response to anti-depressant medication (177)(178)(179), and similarly, this approach can be used to study psychedelics. In 2017, an open label uncontrolled 1 H MRS study was conducted to measure metabolite change in the brain 24 h after (post-acute) administration of ayahuasca (containing 0.64 mg/kg of DMT) in healthy volunteers (180).…”

1H‐MRS reveals metabolic alterations in generalized tonic‐clonic seizures before and after treatment

“…Proton magnetic resonance spectroscopy ( 1 H‐MRS) is a non‐invasive technique which can explore brain metabolism in vivo. It is widely used to investigate various neuropsychiatric diseases such as brain tumors, obsessive‐compulsive disorder, Alzheimer's disease, and epilepsy 10,11 . It can be used to observe many metabolites in the brain, such as N‐acetyl aspartate (NAA), myo‐inositol (Ins), choline (Cho), creatine (Cr), and glutamate +glutamine (Glu + Gln, Glx).…”