Patients experiencing a first episode of psychosis (FEP) have significantly higher homocysteine levels than mentally healthy individuals, researchers report.
However, contrary to the results of numerous studies conducted in bipolar disorder and schizophrenia patients, Rosa Ayesa-Arriola (University of Cantabria, Santander, Spain) and team found no significant associated between increased homocysteine and impaired cognition in FEP patients.
"Our results here do not provide further support for an association between plasma homocysteine levels and cognitive functioning in early phases of psychosis," they write in the European Archives of Psychiatry and Clinical Neuroscience.
The findings come from a study of 139 medication-naïve FEP patients, aged 16-60 years, and 99 mentally healthy individuals (controls), aged 15-50 years.
Blood samples were collected from the participants during a period of fasting and assessed for homocysteine, folate, and vitamin B12 levels.
The participants also completed a neuropsychological test battery to assess information processing speed, motor dexterity, working memory, verbal learning, visuospatial abilities, delayed memory, attention, executive function, and theory of mind.
The team found that homocysteine levels were significantly higher in FEP patients than controls, at 13.64 versus 11.09 µmol/L. And this difference remained significant after accounting for age, gender, smoking, folate, and vitamin B12 levels.
Patients with FEP also had significantly poorer scores in most of the cognitive tests compared with controls.
Using a homocysteine cutoff level of 14.85 µmol/L (>90th percentile of controls), the team found that there were no significant differences in cognitive tests scores between FEP patients with elevated (n=31) versus normal (n=108) levels of the amino acid, after accounting for age, gender, and other variables.
Ayesa-Arriola et al conclude: "We found no evidence for a direct relationship between elevated homocysteine levels and cognitive impairment in FEP patients.
"Nevertheless, our results indicate the need for further studies to clarify the role of homocysteine in the etiology and prognosis of psychosis."
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