Oades, R. D., Henning, U., Röpcke, B., Volberg, G., & Klimke, A. (2001). Associations of neuropsychological task performance with serum indices of monoamine activity in schizophrenia subgroups: noradrenaline and verbal recall. World Journal of Biological Psychiatry, 2, 233.

Background levels of dopamine (DA), noradrenaline (NA) and serotonin (5-HT) activity (metabolite/amine) modulate different aspects of information processing (e.g. switching, tuning and volume control) [1].

We studied the extent to which serum indicators of monoamine activity predicted performance on ten neuropsychological measures. Subjects were 63 controls and 108 with schizophrenia and subgroups based on 4 PCA-derived dimensions (paranoid/positive, nonparanoid/negative, thought disorder and ideas-of-reference) with different levels or ratios of monoamine activity [2].

(1) In the whole patient group and those with nonparanoid symptoms or high levels of thought disorder decreasing NA utilization (MHPG/NA) related to better verbal fluency but more Stroop-interference, and poorer delayed recall of stories.
(2) Poorer immediate recall was associated with lower DA utilization (HVA/DA) in the whole patient group (but especially the nonparanoid group), as well as those patients with few ideas of reference and little thought disorder (respectively, over 15% & 18% of variance explained).
(3) However, increased DA turnover in those with many ideas of reference was related to improved set-switching on the trails-task (Trails B - A, 20% of variance explained)
(4) Regressions showed 5-HT activity had few associations, but increased HVA/5-HIAA ratios were associated positively with visual reproduction and Mooney-faces performance (right hemisphere functions).
(5) Decreasing HVA/MHPG ratios were associated with nonverbal recall.

We conclude that (a) high NA activity can impair left frontal but aid temporal lobe function, that (b) low DA activity impairs attentional set shifting and memory, (c) the ratio of DA to NA-or-5-HT metabolism modulates right hemnisphere function, and (d) inter amine ratios reflect in part neuroleptic levels of DA D2 occupancy (with effects emphasizing left hemisphere function). The results are consistent with others demonstrating a mnemonic role for central NA activity [3], but that modulation by DA is important in patients with few positive symptoms.

[1]. Oades, R. D. (1985). The role of noradrenaline in tuning and dopamine in switching between signals in the CNS. Neurosci. Biobehav. Rev., 9, 261-283
[2]. Oades et al. (2001) World J Biol Psychiat, 2, 286 (poster at this meeting),
[3]. Avery R. A. et al., (2000). The alpha-2A-adrenoceptor agonist guanfacine, increases regional cerebral blood flow in dorsolateral prefrontal cortex in monkeys performing a spatial working memory task. Neuropsychopharmacol., 23, 240-249. Support: DFG (OA 1/4-1&2)