Oades, R. D., R÷pcke, B., Henning, U., Klimke, A., & Rao M. L., (2002).
Neuropsychologic function, serum monoamine activity, and dimensions of schizophrenia.
Schizophrenia Research, 53 (supplement), p. 148.

Introduction: Different aspects of information processing (attention and memory) are modulated by high and low levels or ratios of the monoamines dopamine (DA), noradrenaline (NA) and serotonin (5-HT). Indicators of monoamine activity in turn characterise different subgroups of schizophrenia (Oades et al., 2002)..

Methods: We studied
a) the extent to which serum indicators of monoamine activity predicted performance on ten neuropsychological measures reflecting lateralised frontal, parietal and temporal lobe involvement (e.g., verbal fluency, trails, picture-completion, block-design, Stroop, Mooney-faces and visual/verbal memory).
b) Serum levels of the 3 monoamines and their main metabolites taken from 63 healthy controls and 108 patients with schizophrenia were analysed with HPLC (i.e., Dopamine (DA), Noradrenaline (NA), Serotonin (5-HT), Homovanillic acid (HVA), 3-methoxy-4-hydroxy-phenyl glycol (MHPG), & 5-hydroxyindoleacetic acid (5-HIAA).
c) Subgroups were based on 4 PCA-derived dimensions of PANSS-SAPS symptom ratings (paranoid, nonparanoid, thought disorder and ideas-of-reference).


Results:
First:

a) For non-paranoid and thought-disordered patients verbal fluency and Stroop-interference (left fronto-cingulate function) were negatively associated with NA turnover:
b)
but delayed verbal recall (left temporal lobe function) showed a positive association.
Second:
a) Those with many ideas-of-reference showed a relationship between trails (trails B-A) and high DA turnover.
b) Low DA turnover in non-paranoid patients and those with little thought disorder related to poor immediate recall.

Third:
a)
Visual-reproduction and Mooney-faces performance was predicted by increased HVA/5-HIAA ratios,
b) but decreased HVA/MHPG predicted non-verbal recall.


Conclusions: In general, right hemisphere functions appeared sensitive to the ratio of the activity of DA to the other amines. Depending on the symptom clusters expressed, --
-- low mesocortical DA activity may impair set-shifting and memory,
--
while NA activity was associated with enhanced frontal but impaired temporal lobe function.
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