Inflammation linked to cognitive impairments in bipolar disorder
medwireNews: Increased inflammation may explain why some patients with bipolar disorder have cognitive deficits even when they are not having a mood episode, say researchers.
Patients in their study who had high levels of the inflammatory marker C-reactive protein (CRP) were at increased risk for having poor scores in a battery of cognitive tests, report Faith Dickerson (Sheppard Pratt, Baltimore, Maryland, USA) and co-workers.
"This finding builds on our previous studies in which we found an effect of CRP on overall cognitive functioning in individuals with schizophrenia," they write in the Journal of Affective Disorders.
There were 107 patients in the study and 210 controls with no psychiatric illness. In all, 41% of the patients had a Repeatable Battery for the Assessment of Neuropsychological Status (RBANS) score of 70 or below, which is two standard deviations below the expected average.
Patients with a serum CRP level above the 90th percentile of control levels had a 4.3-fold increased risk for having a low RBANS score, and those with a CRP level above the 75th percentile had a 3.1-fold increased risk. The associations were independent of variables including age, gender, race, maternal education, Young Mania Rating Scale score, and Hamilton Depression Scale score.
The only individual RBANS component significantly associated with high CRP levels was delayed memory, with patients above the 90th percentile of CRP levels being 3.96-fold more likely to have low scores in this test, relative to those with lower levels.
However, patients' scores for the RBANS components immediate memory, attention, and language showed significant and inverse linear correlations with CRP levels, as did their performance in the Trail Making Test A, which measures cognitive processing speed.
"The reasons for the association between CRP and cognitive impairment are not known with certainty but are likely to be related to inflammatory processes occurring within the vasculature of the central nervous system," say Dickerson et al.
They add: "It is of note that new therapeutic modalities are being developed which modulate the inflammatory response and lower levels of CRP."
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By Eleanor McDermid, Senior medwireNews Reporter