Homocysteine not linked to cognitive impairments in schizophrenia
MedWire News: Homocysteine levels are increased in patients with schizophrenia, but are not associated with cognitive impairments, results from a Spanish study show.
"Homocysteine is a non-protein neurotoxic amino acid that has been proposed as an independent risk factor for schizophrenia through developmental effects on brain structure and function," explain Rosa Ayesa-Arriola (University of Cantabria, Santander) and team.
They add: "Increased total plasma homocysteine levels have been associated with cognitive dysfunction in a wide array of neurological and psychiatric disorders."
To investigate the relationship between homocysteine levels and cognitive deficits in psychosis patients, the team studied 139 patients (46% women), aged a mean of 32 years, who had experienced a first psychotic episode and 99 mentally healthy controls (41% women), aged a mean of 27 years.
All of the participants provided blood samples for analysis of homocysteine levels, and were evaluated using a variety of cognitive tests for processing speed, motor dexterity, working memory, verbal learning, visuospatial abilities, delayed memory, attention, executive function, and theory of mind.
The researchers found that patients with psychosis had significantly higher mean homocysteine levels compared with controls, at 13.64 versus 11.09 µmol/L.
Of the patients with psychosis, 31 were classified as having elevated homocysteine levels (>90th percentile for controls), with the remaining 108 patients classified as having normal levels.
As expected, patients with psychosis scored worse than controls on most of the cognitive tests used in the study.
However, among the psychosis patients, there was no significant difference in measures of cognition between those with and without elevated levels of homocysteine.
Ayesa-Arriola and team conclude in the European Archives of Psychiatry and Clinical Neuroscience: "We found no evidence for a direct relationship between elevated homocysteine levels and cognitive impairment in first-episode psychosis 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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By Mark Cowen