Alteration of Monoamine Receptor Activity and Glucose Metabolism in Pediatric Patients with Anticonvulsant-Induced Cognitive Impairment
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Alteration of Monoamine Receptor Activity and Glucose Metabolism in Pediatric Patients with Anticonvulsant-Induced Cognitive Impairment Yuankai Zhu*1–4, Jianhua Feng*5, Jianfeng Ji*1–4, Haifeng Hou1–4, Lin Chen1–4, Shuang Wu1–4, Qing Liu1–4, Qiong Yao1–4, Peizhen Du1–4, Kai Zhang1–4, Qing Chen1–4, Zexin Chen6, Hong Zhang1–4, and Mei Tian1–4 1Department of Nuclear Medicine, The Second Hospital of Zhejiang University School of Medicine, Hangzhou, China; 2Zhejiang University Medical PET Centre, Zhejiang University, Hangzhou, China; 3Institute of Nuclear Medicine and Molecular Imaging, Zhejiang University, Hangzhou, China; 4Key Laboratory of Medical Molecular Imaging of Zhejiang Province, Hangzhou, China; 5Department of Paediatrics, The Second Hospital of Zhejiang University School of Medicine, Hangzhou, China; and 6Department of Clinical Epidemiology & Biostatistics, The Second Hospital of Zhejiang University School of Medicine, Hangzhou, China children with epilepsy is timely and imperative (1). Cognitive A landmark study from the Institute of Medicine reported that the impairment is the most common side effect of anticonvulsants, assessment of cognitive difficulties in children with epilepsy is timely and the risk may accumulate when anticonvulsants are combined and imperative. Anticonvulsant-induced cognitive impairment could (2). Particularly, the developing brains of pediatric patients appear influence the quality of life more than seizure itself in patients. to be particularly sensitive to the cognitive adverse effects of Although the monoaminergic system is involved in the regulation anticonvulsants due to the age-related pharmacokinetic and phar- of cognitive process, its role in anticonvulsant-induced cognitive macodynamic features (3). impairment remains unclear. Methods: To explore in vivo mono- PET is ideally suited for monitoring cell/molecular events early amine receptor binding activity in patients with anticonvulsant- induced cognitive impairment, each patient underwent PET imaging in the course of a disease, as well as during pharmacologic with both monoamine receptor binding agent 11C-N-methylspiperone or radiation therapy (4). Among PET radioligands for mapping 11 11 and glucose metabolic agent 18F-FDG. Tests of intelligence quo- postsynaptic monoamine receptors, C-labeled raclopride ( C- tient (IQ), including verbal IQ (VIQ), performance IQ (PIQ), and raclopride) is the most often used as a standard D2 dopamine full-scale IQ (FSIQ), were performed in each patient. Results: Com- receptor (D2DR) ligand (5). However, because the binding of 11 pared with the patients with monotherapy, patients with polytherapy C-raclopride to the D2DR in the striatum is competitive with had significantly lower VIQ, PIQ, and FSIQ (P , 0.01 in each com- that of endogenous dopamine and reversible in the time frame parison), as well as significantly lower monoamine receptor activi- of a PET scan, it could not reflect the actual changes of postsyn- ties detected in the caudate nucleus, prefrontal cortex, dorsal aptic receptor level. In contrast, the binding of 11C-N-methylspi- anterior cingulate cortex, and amygdale (P , 0.05 in each compar- perone (11C-NMSP; as a D DR and 5-hydroxytryptamine receptor ison). However, regarding the glucose metabolism, there was no 2 significant difference found in patients with monotherapy or poly- 2A [5-HT2AR] antagonist, not competitive with that of en- therapy (P . 0.05). Conclusion: Monoamine receptor PET imaging dogenous dopamine (5,6) and serotonin (7)) can directly reflect 11 could be a promising in vivo imaging biomarker for mapping anti- postsynaptic monoamine receptor levels more accurately than C- convulsant-induced cognitive impairment. raclopride. Although the monoaminergic system is involved in the Key Words: epilepsy; cognition; anticonvulsant; monoamine receptor; regulation of cognitive process, its role in anticonvulsant-induced positron emission tomography (PET) cognitive impairment remains unclear (8,9). Therefore, we performed 11C-NMSP PET studies to examine the alteration of monoamine J Nucl Med 2017; 58:1490–1497 DOI: 10.2967/jnumed.116.189290 receptor activity in pediatric patients with anticonvulsant-induced cognitive impairment. MATERIALS AND METHODS Subjects A landmark study from the Institute of Medicine reports that Twenty-five patients (13 males; mean age 6 SD, 13.7 6 2.0 y) the chance of developing epilepsy at some point in our lives is 1 in diagnosed with epilepsy (10) were enrolled in this study (Table 1). 26 and recommends that the assessment of cognitive difficulties in Sixteen right-handed healthy control participants (9 males; mean age 6 SD, 21.6 6 1.3 y) with no history of neuropsychiatric disorders or receiving psychoactive drugs were included. The Institutional Re- Received Dec. 29, 2016; revision accepted Feb. 27, 2017. view Board approved this study (ChiCTR-DDD-15007423), and writ- For correspondence or reprints contact: Mei Tian, Department of Nuclear Medicine, The Second Hospital of Zhejiang University, 88 Jiefang Rd., ten informed consent was obtained from each participant. Hangzhou, Zhejiang 310009, China. The patient inclusion criteria were as follows: clinical and E-mail: [email protected] electroencephalogram findings indicative of focal seizure, age *Contributed equally to this work. Published online Mar. 16, 2017. 10–18 y, receiving at least 1 anticonvulsant and without alteration of COPYRIGHT © 2017 by the Society of Nuclear Medicine and Molecular Imaging. its dosage in the 3 mo before this study, without developmental 1490 THE JOURNAL OF NUCLEAR MEDICINE • Vol. 58 • No. 9 • September 2017 TABLE 1 disabilities, without history of addictions or other psychiatric illnesses, Clinical Characteristics and Comparisons Between and right-handedness. Patients were excluded if they had identified Mono- and Polytherapy Groups epileptic encephalopathies or had comorbidities including depression, anxiety, and attention deficit hyperactivity disorder rather than cogni- Anticonvulsant tive impairment. Other exclusion criteria were diagnosis of tuberous sclerosis, tumors, or major hemispheric deformity (such as hemime- Monotherapy Polytherapy galencephaly and porencephaly), becuase these lesions preclude the Clinical characteristic (n 5 12) (n 5 13) P normalization of PET images. Sex Each patient underwent at least 1 prolonged (24 h) electroen- cephalogram monitoring to confirm the localization of the epileptic Female/male 7/5 5/8 0.434 foci. Video-electroencephalography was performed in 5 patients who Age (y) 13.3 ± 1.9 14.1 ± 2.1 0.302 presented difficulties in lesion localization. Tests of intelligence Age of onset (y) 7.6 ± 3.0 8.8 ± 1.9 0.250 quotient (IQ), including verbal IQ (VIQ), performance IQ (PIQ), Duration of epilepsy (y) 5.7 ± 2.9 5.3 ± 2.2 0.749 and full-scale IQ (FSIQ), were performed using the Chinese version of the Wechsler Intelligence Scale for Children (C-WISC) or Adults IQ (C-WISA). Verbal 105.6 ± 17.5 81.9 ± 19.6 0.004 Performance 115.3 ± 12.7 86.9 ± 25.5 0.002 PET Imaging with 11C-NMSP and 18F-FDG Full-scale 111.5 ± 16.7 83.4 ± 22.6 0.002 The PET imaging studies were done using a clinical PET/CT scanner (Biograph mCT; Siemens Medical Solutions). Dynamic scans MRI were obtained at 0–40 min after a bolus intravenous injection of 11C- Abnormal/normal 2/10 2/11 1.000 NMSP (3.7 MBq/kg) (11). A 5-min static brain scan was acquired at Type of epilepsy 1.000 40 min after injection of 18F-FDG (3.7 MBq/kg) (12). Interictal PET RE 6 7 studies were performed in patients at least 24 h after the last clinical seizure. A pediatric physician carefully monitored each subject during TLE 5 5 the entire PET imaging study. Frontal lobe epilepsy 1 1 Seizure activity PET Data Analysis Resistance/remission 10/2 5/8 0.041 Regions of interest were drawn on both hemispheres in the stereotactically normalized images. Voxel-based analysis of asymme- try index (AI) was conducted according to the previous study using statistical parametric mapping (SPM8) (13). Briefly, AI images were calculated at each voxel according to the fol- lowing formula: AI 5 (left 2 right)/([left 1 right]/2). In the case of the patients with ep- ileptic foci in the right hemisphere, the orien- tation of AI images were flipped along to the sagittal plane. AI images of patients were then compared with the controls, using the 2-sample t test of the SPM software package, with an ANCOVA by each subject. Decreased or increased results were regarded as statisti- cally significant if the uncorrected P value was under 0.001 (18F-FDG) or 0.01 (11C- NMSP), respectively, with cluster level above 100 voxels. Statistical Analysis The results are presented as mean 6 SD. All data were analyzed by IBM SPSS Sta- tistics (version 20.0; SPSS/IBM). Analysis of correlation was performed using Pearson correlation coefficients. Group differences in sex, age, age of onset, duration of epilepsy, MRI abnormality, epilepsy type, and IQ were tested using the 2-sample t test or Fisher ex- act test as appropriate. Stepwise multivariate linear regression analysis was conducted to FIGURE 1. Anticonvulsant-induced cognitive impairment and alteration of monoamine receptor determine the independent contribution of in- activity in caudate nucleus. (A–C) VIQ, PIQ, and FSIQ were significantly lower in patients with dividual variables (sex, age, age of onset, du- polytherapy compared with those with monotherapy (P , 0.01 in each comparison). (D–F) 11C- NMSP bindings in left, right, or entire caudate nucleus were significantly lower in patients with ration of epilepsy, time since last seizure, polytherapy than in those with monotherapy (P , 0.05 in each comparison). (G–I) VIQ, PIQ, and seizure frequency, lateralization of epileptic FSIQ were significantly positively correlated with 11C-NMSP binding in caudate nucleus (r 5 foci, epilepsy type, MRI abnormality, and 0.437, 0.532, and 0.487, respectively, P , 0.05 in each comparison). combination of anticonvulsant) to the IQ or PET IMAGING OF COGNITIVE IMPAIRMENT • Zhu et al. 1491 radiotracer. A P value of less than 0.05 was considered statistically seizure frequency (P 5 0.348, 0.338, and 0.424, respectively), significant.