Evaluation of semi-quantitative method for quantification of dopamine transporter in human PET study with ¹⁸F-FE-PE2I

OBJECTIVES

Positron emission tomography (PET) with ¹⁸F-FE-PE2I is useful for investigating the function of dopamine transporter, and kinetics of ¹⁸F-FE-PE2I could be described by standard two-tissue compartment model (2CM) using plasma input function. In this study, we investigated the feasibility of semi-quantitative methods for estimating binding potential (BPND) and transporter occupancy to shorten the scan period and to reduce the effect of statistical noise on quantitative outcomes using computer simulation and human PET studies with ¹⁸F-FE-PE2I.

METHODS

In the simulations, time-activity curves (TACs) for the putamen with a wide range of BPND were generated. In these TACs, BPNDs were estimated by standardized uptake value ratio (SUVR) using various integration intervals and the simplified reference tissue model (SRTM) with the cerebellum as reference region, and reduction of BPND assuming transporter occupancy by antipsychotics was calculated from BPND obtained from TACs with various BPND values. These estimates were evaluated by comparison with those of 2CM. In human studies with normal volunteers, BPNDs were estimated in the caudate and putamen using SUVR and SRTM with the cerebellar reference region, and compared with BPND by standard 2CM.

RESULTS

In the simulations, BPND estimated by SUVR with late time frames and SRTM showed linear correlation with those by 2CM, although the estimates by SUVR were overestimated and affected by the cerebral blood flow as BPND became higher. As for transporter occupancy, SRTM showed higher linearity with 2CM and less effect of statistical noise than the SUVR method. In human studies, BPND by SRTM and SUVR with late time frames showed good correlation with BPND by 2CM.

CONCLUSIONS

Although SRTM is more reliable than the SUVR method for BPND and occupancy estimation, SUVR using late time frames has the potential to provide practical indices of BPND and occupancy with a shorter scan period.

Amyloid imaging with [(18)F]florbetapir in geriatric depression: early-onset versus late-onset

BACKGROUND

We examined patients with mild cognitive impairment (MCI) with a history of geriatric depression (GD) and healthy controls (HC) to evaluate the effect of beta-amyloid (Aβ) pathology on the pathology of GD by using [(18)F]florbetapir PET.

METHODS

Thirty-three elderly patients (76.7 ± 4.2 years) and 22 healthy controls (HC; 72.0 ± 4.5 years, average ± SD) were examined by [(18)F]florbetapir positron emission tomography (PET) to quantify the standard uptake value ratio (SUVR) as the degree of amyloid accumulation, by MRI to determine the degree of atrophy, by Mini-Mental State Examination for cognitive functions, and by Geriatric Depression Scale for the severity of depression, and by Clinical Dementia Rating for activity of daily living (ADL). The cut-off value of 1.08 for SUVR was defined as Aβ-positive.

RESULTS

Of the patients and HC, 39.4% and 27.3%, respectively, were beta-amyloid-positive. The onset age of GD was significantly correlated with SUVR (r = 0.44, p < 0.01). Compared to patients without Aβ (GD-Aβ), patients with Aβ (GD + Aβ) did not differ in terms of age, cognitive function, severity of depression and ADL, and brain atrophy. GD + Aβ had significantly older average ± SD age at onset of GD (73.6 ± 7.1 versus 58.7 ± 17.8, p < 0.01) and significantly shorter average ± SD time between onset of GD and PET scan day (3.1 ± 5.2 years versus 18.1 ± 18.6 years, p < 0.001) than GD-Aβ.

CONCLUSIONS

Our results showed that the rate of Aβ positivity was higher in late-onset GD and that onset-age was associated with SUVR, suggesting that the later the onset of GD, the more Aβ pathology affected its onset.

Treatment for female patients with eating disorders in the largest medical prison in Japan

The number of offenders with eating disorders in women’s prisons in Japan has grown annually over the last 15 years. Women’s prisons have experienced significant difficulties in the management of patients with eating disorders who have body-critical complications arising from low body weight, in addition to behavioral problems. Patients in Japan’s 185 correctional facilities who display high refractoriness or who present a physical risk are transferred to the Hachioji medical prison, a national specialty hospital operated by the Ministry of Justice. The medical prison must manage any psychosomatic problems necessary for the safety of inmates regardless of a patient’s wishes. The most common conviction resulting in imprisonment of women with eating disorders was shoplifting (n = 44; 63%), with the second most common being drug-offenses (n = 17; 24%). While shoplifting is of concern in relation to eating disorders, a causal relationship remains unclear. Most patients in the shoplifting group did not have histories of antisocial and/or impulsive behaviors such as drug abuse, sexual deviation, self-injury, or other criminal activity. Instead, shoplifting appears to be an obsessive-compulsive behavior deeply rooted in the psychopathology of severe eating disorder patients. Patients in this group tended to have histories of relatively high education and steady employment, although most also had histories of prolonged eating disorders and unstable treatment. Although adherence to treatment was poor among patients with eating disorders in the medical prison, body weight and behavioral problems improved following treatment in the special compulsory environment, without severe sequelae or patient death. The Ministry of Justice recently established another specialized ward for the care for female patients with eating disorders. If greater emphasis is placed on early-stage, protective, medical treatment, the number of patients with eating disorders in prisons may decrease. Further research is required to investigate the relationship between shoplifting and eating disorders.

Imaging characteristics and safety of florbetapir (¹⁸F) in Japanese healthy volunteers, patients with mild cognitive impairment and patients with Alzheimer's disease

OBJECTIVE

The purpose of this study was to evaluate the performance characteristics and safety of florbetapir ((I8)F) positron emission tomography (PET) in patients with Alzheimer's disease (AD) and mild cognitive impairment (MCI) and cognitively normal (CN) control patients from Japan.

METHODS

Florbetapir ((I8)F) PET was obtained in 48 subjects (15 AD patients, 15 MCI patients, and 18 CNs) within a multicenter phase 2/3 study. Amyloid burden was assessed visually and classified as positive or negative for pathologic levels of amyloid aggregation, blind to diagnostic classification. Cerebral to cerebellar standardized uptake value ratios (SUVRs) were determined from the florbetapir ((I8)F) PET images. Safety was assessed by monitoring adverse events, vital signs, clinical laboratory assessments, and electrocardiograms. Demographic variables and cognitive scales were summarized by using descriptive statistics for each group. Fisher's exact test and one-way analysis of variance were used to compare amyloid positivity and mean SUVRs, respectively, between diagnostic groups.

RESULTS

Florbetapir ((I8)F) PET was rated visually amyloid positive in 80.0% of AD patients, 33.3% of MCI patients, and 16.7% of CNs. Mean SUVRs were highest in the AD group and lowest in the CN group for each brain region (P < 0.01) and globally (P < 0.05). Kappa statistics showed strong inter-reader agreement (Fleiss' kappa = 0.82) and individual reader's agreement with the majority of readers (kappa ranged from 0.79 to 1.0). Seventeen of the 48 subjects (35.4%) were Apolipoprotein E genotype ε4 positive, which included 10 subjects in the AD group and 7 subjects in the MCI group. A total of 6 subjects (5 of whom were in the CN group) had at least 1 treatment-emergent adverse event (TEAE).

CONCLUSIONS

These data indicate that amyloid positivity increased with diagnostic category (CN < MCI < AD) and are consistent with expected rates of amyloid positivity among individuals with clinical diagnoses of AD and MCI. In addition, these results were similar to those obtained in United States studies. Florbetapir ((18)F) was safe and well tolerated. The reliability of both qualitative and quantitative assessments of florbetapir ((18)F) in this study population provides support for potential use in clinical settings in Japan.

Comparison of imaging biomarkers for Alzheimer's disease: amyloid imaging with [18F]florbetapir positron emission tomography and magnetic resonance imaging voxel-based analysis for entorhinal cortex atrophy

OBJECTIVE

We compared amyloid positron emission tomography (PET) and magnetic resonance imaging (MRI) in subjects clinically diagnosed with Alzheimer's disease (AD), mild cognitive impairment (MCI), and older healthy controls (OHC) in order to test how these imaging biomarkers represent cognitive decline in AD.

METHODS

Fifteen OHC, 19 patients with MCI, and 19 patients with AD were examined by [(18)F]florbetapir PET to quantify the standard uptake value ratio (SUVR) as the degree of amyloid accumulation, by MRI and the voxel-based specific regional analysis system for AD to calculate z-score as the degree of entorhinal cortex atrophy, and by mini-mental state examination (MMSE) and Alzheimer's Disease Assessment Scale-cognitive component--Japanese version (ADAS-Jcog) for cognitive functions.

RESULTS

Both cutoff values for measuring AD-like levels of amyloid (1.099 for SUVR) and entorhinal cortex atrophy (1.60 for z-score) were well differentially diagnosed and clinically defined AD from OHC (84.2% for SUVR and 86.7% for z-score). Subgroup analysis based on beta-amyloid positivity revealed that z-score significantly correlated with MMSE (r = -0.626, p < 0.01) and ADAS-Jcog (r = 0.691, p < 0.01) only among subjects with beta-amyloid.

CONCLUSIONS

This is the first study to compare [(18)F]florbetapir PET and MRI voxel-based analysis of entorhinal cortex atrophy for AD. Both [(18)F]florbetapir PET and MRI detected changes in AD compared with OHC. Considering that entorhinal cortex atrophy correlated well with cognitive decline only among subjects with beta-amyloid, [18F]florbetapir PET makes it possible to detect AD pathology in the early stage, whereas MRI morphometry for subjects with beta-amyloid provides a good biomarker to assess the severity of AD in the later stage.

Comparison of regional gray matter volume abnormalities in Alzheimer׳s disease and late life depression with hippocampal atrophy using VSRAD analysis: a voxel-based morphometry study

Previous voxel-based morphometry (VBM) studies revealed that hippocampal volume loss in patients with late life depression (LLD) is associated with cognitive impairment and a higher risk for dementia. However, LLD patients can experience hippocampal atrophy without cognitive impairment. Thus, while LLD and AD can show comparable hippocampal atrophy, they may encompass different neuropathological changes. Using VBM, we therefore investigated differences in regional gray matter changes in 17 late-onset LLD patients and 21 AD patients (without a history of LLD) who exhibited comparably severe atrophy of the entorhinal cortex and the parahippocampal gyrus on MRI scans for voxel-based specific regional analysis system for AD (VSRAD). Relative to the VSRAD database for healthy individuals, significant atrophy was observed in mesial temporal lobe structures and the anterior cingulate cortex in both groups. Atrophy of the posterior cingulate cortex and precuneus was observed only in the AD group. Comparisons of gray matter volume by multivariate analysis of variance revealed significantly reduced volume of the right middle and inferior temporal gyrus, uncus, posterior cingulate cortex, and precuneus in the AD group only, suggesting impairment of different networks in AD and LLD. Indeed, structural changes in the posterior part of the default-mode network are believed to be associated with cognitive impairments specific to AD.

Interaction effect between handedness and CNTNAP2 polymorphism (rs7794745 genotype) on voice-specific frontotemporal activity in healthy individuals: an fMRI study

Recent neuroimaging studies have demonstrated that Contactin-associated protein-like2 (CNTNAP2) polymorphisms affect left-hemispheric function of language processing in healthy individuals, but no study has investigated the influence of these polymorphisms on right-hemispheric function involved in human voice perception. Further, although recent reports suggest that determination of handedness is influenced by genetic effect, the interaction effect between handedness and CNTNAP2 polymorphisms for brain activity in human voice perception and language processing has not been revealed. We aimed to investigate the interaction effect of handedness and CNTNAP2 polymorphisms in respect to brain function for human voice perception and language processing in healthy individuals. Brain function of 108 healthy volunteers (74 right-handed and 34 non-right-handed) was examined while they were passively listening to reverse sentences (rSEN), identifiable non-vocal sounds (SND), and sentences (SEN). Full factorial design analysis was calculated by using three factors: (1) rs7794745 (A/A or A/T), (2) rs2710102 [G/G or A carrier (A/G and A/A)], and (3) voice-specific response (rSEN or SND). The main effect of rs7794745 (A/A or A/T) was significantly revealed at the right middle frontal gyrus (MFG) and bilateral superior temporal gyrus (STG). This result suggests that rs7794745 genotype affects voice-specific brain function. Furthermore, interaction effect was significantly observed among MFG-STG activations by human voice perception, rs7794745 (A/A or A/T), and handedness. These results suggest that CNTNAP2 polymorphisms could be one of the important factors in the neural development related to vocal communication and language processing in both right-handed and non-right-handed healthy individuals.

The noradrenaline metabolite MHPG is a candidate biomarker between the depressive, remission, and manic states in bipolar disorder I: two long-term naturalistic case reports

BACKGROUND

Treatment of the depressive and manic states in bipolar disorder I (BDI) is a challenge for psychiatrists. Despite the recognized importance of the switch phenomenon, the precise mechanisms underlying this process are yet to be shown. We conducted a naturalistic study in two BDI patients to determine whether biological markers (monoamine metabolites and brain-derived neurotrophic factor [BDNF]) are associated with the switch between depressive and manic states.

CASE PRESENTATION AND METHODS

Blood sampling and mood assessments were performed at 2-week intervals over a period of 2 (Case 1, n=72) and 6 (Case 2, n=183) years. Plasma concentrations of 3-methoxy-4-hydroxyphenylglycol (MHPG) and homovanillic acid (HVA) were analyzed by high-performance liquid chromatography with electrochemical detection. Plasma BDNF was assayed by sandwich ELISA (enzyme-linked immunosorbent assay).

RESULTS

MHPG had the highest standardized coefficient (β) in the multiple regression analysis. We found a significant positive correlation between Young Mania Rating Scale scores and plasma MHPG levels (Case 1: ρ=0.429; Case 2: ρ=0.488), and a significant negative correlation between Montgomery-Asberg Depression Rating Scale scores and MHPG levels (Case 1: ρ=-0.542; Case 2: ρ=-0.465). Conversely, no significant correlation was found between the level of BDNF and the presence of a manic or depressive state, and although HVA had a slightly stronger correlation than MHPG, the levels of neither of these were found to significantly correlate with the symptoms.

CONCLUSION

These data suggest that peripheral MHPG levels (which is related to noradrenaline levels in the brain) could be used as a biomarker of mood states in BDI. The noradrenaline level in the brain is likely to reflect the clinical characteristics of the switch process in BDI, and has prognostic significance for the treatment of both manic and depressive states.

Modafinil augments brain activation associated with reward anticipation in the nucleus accumbens

RATIONALE

The nucleus accumbens (NAc) works as a key brain structure of the reward system, in which reward-related neural activity is well correlated with dopamine release from mesolimbic dopaminergic neurons.

OBJECTIVES

Since modafinil can modulate dopaminergic transmission through re-uptake inhibition of dopamine, we investigated whether modafinil affects the reward-related brain activity in the NAc in healthy subjects.

METHODS

Twenty healthy participants underwent two series of functional magnetic resonance imaging while performing monetary incentive delay task in which they were cued to anticipate and respond to a rapidly presented target to gain or avoid losing varying amounts of money, under modafinil or placebo condition. Blood oxygenation-level dependent (BOLD) activation signals during gain and loss anticipations were analyzed in the NAc as an a priori region of interest as well as the whole brain.

RESULTS

Modafinil significantly changed subjective feelings toward positive ones. The activation of BOLD signals was observed during gain anticipation under the placebo and modafinil conditions in the left and bilateral NAc, respectively. The modafinil condition showed significantly higher BOLD signal change at the highest gain (+¥500) cue compared to the placebo condition.

CONCLUSIONS

The present study showed that modafinil affects reward processing in the NAc in healthy subjects through enhancing more positive anticipation, and it may provide a basis for the use of this drug for treating anhedonia observed in psychiatric disorders.

Eating disorders among patients incarcerated only for repeated shoplifting: a retrospective quasi-case-control study in a medical prison in Japan

BACKGROUND

Shoplifting is a serious problem among patients with eating disorders. For more than a decade, we have treated many patients with eating disorders incarcerated in Hachioji Medical Prison only for repeated shoplifting.

METHODS

We analyzed the prison records and medical records of female psychiatric patients transferred to Hachioji Medical Prison between 2002 and 2011. Based on the offense listed at the time of sentencing, we extracted a shoplifting group and a drug-offense group from among all patients with eating disorders. One patient from the former group who had used substances and two from the latter group who had never shoplifted were excluded from the study. The groups had 41 and 14 patients, respectively. A control group comprised patients with other mental disorders (n = 34). We compared eating disorder histories and subtypes, weight changes, comorbidities, life histories, past behavioral problems, and clinical behavioral problems among the three groups.

RESULTS

The shoplifting group exhibited less impulsive behavior, substance abuse, antisocial features, borderline personality disorder, and past bulimia than did the drug-offense and control groups. The shoplifting group had higher educational achievement and steadier employment; however, their eating disorder histories and interpersonal dysfunction were more severe, and they had a higher psychiatric treatment dropout rate. There were also significant relationships with low body weight, anorexia nervosa-restricting type, obsessive-compulsive behaviors, and obsessive-compulsive personality disorder in the shoplifting group. During the clinical course, food refusal, excessive exercise, food hoarding, and falsification of dietary intake amounts were more frequently observed in the shoplifting group. Conversely, drug requests and occurrences of self-harm were less frequent in the shoplifting group than in the drug-offense group.

CONCLUSIONS

Although these results may be associated with specific characteristics of patients with eating disorders in the medical prison setting, we concluded that the repeated shoplifting by these patients is unrelated to antisocial or impulsive characteristics but is deeply rooted in these patients' severe and undertreated eating disorder psychopathology. Strong supportive treatment should be considered for patients with eating disorders who develop shoplifting behaviors. Further research is required to elucidate the mechanisms responsible for the relationship between shoplifting and eating disorders.

Gender differences in suicide attempters: a retrospective study of precipitating factors for suicide attempts at a critical emergency unit in Japan

BACKGROUND

There is a shortage of empirical data concerning precipitating factors for suicides in Japan. The purpose of the present study was to clarify gender differences of precipitating factors for suicide attempts in Japan.

METHODS

The subjects were high-lethality suicide attempters who were admitted to the Nippon Medical School Hospital Critical Care Medical Center between March 1, 2010 and March 31, 2012. Precipitating factors for suicide attempt, method of suicide attempt, psychiatric diagnoses and other sociodemographic data were collected from the patients' medical records retrospectively, and statistical analyses were performed for categorical variables of male/female.

RESULTS

The total number of subjects was 193 (88 males and 105 females). The rate of subjects attempting suicide by poisonous gas was significantly higher in males while that of subjects attempting suicide by drug overdose was significantly higher in females. The rate of subjects diagnosed with "major depressive disorder, bipolar disorder" was significantly higher in males while that of subjects diagnosed with "personality disorders" or "dysthymic disorder" was significantly higher in females. Subjects with "health problems", "financial problems", "work problems", "debts (others)" or "unwanted transfer" were significantly more numerous among males; subjects with "family problems", "parent-child relations" or "loneliness" were significantly more frequently found among females.

CONCLUSIONS

Mental disorders were the most common precipitating factor for suicide attempts regardless of gender. Significant gender differences were observed in psychiatric diagnoses, methods of suicide attempt and psychosocial problems. This indicates the necessity of suicide prevention measures corresponding to these gender differences.

Association of alcohol consumption with incident hypertension among middle-aged and older Japanese population: the Ibarakai Prefectural Health Study (IPHS)

The objective of this study was to examine the effect of age on the relationship between alcohol consumption and incident hypertension in a general Japanese population. A cohort of Japanese men (n=37 310) and women (n=78 426) aged 40 to 79 years who underwent community-based health checkups from 1993 to 2004 and were free of hypertension were followed up with annual examinations, including the measurement of blood pressure, until the end of 2010. Incident hypertension was defined as systolic blood pressure of ≥140 mm Hg, diastolic blood pressure of ≥90 mm Hg, or the initiation of treatment for hypertension. Hazard ratios for incident hypertension according to alcohol consumption were estimated using a Cox proportional hazards model adjusted for possible confounding variables. A total of 45 428 participants (39.3%) developed hypertension (16 155 men and 29 273 women) for a mean follow-up time of 3.9 (1-18) years. Significant associations between alcohol consumption and incident hypertension were found in both sexes and age groups (P for trend was <0.001 for men aged 40-59 years and aged 60-79 years; 0.004 for women aged 40-59 years and 0.026 for women aged 60-79 years). No significant interaction with age on the association of alcohol consumption with incident hypertension was found in either sex (P for interaction, >0.05). Our results suggest that alcohol consumption is a similar risk factor for incident hypertension in both the middle-aged and the older populations.

Cerebral responses to vocal attractiveness and auditory hallucinations in schizophrenia: a functional MRI study

Impaired self-monitoring and abnormalities of cognitive bias have been implicated as cognitive mechanisms of hallucination; regions fundamental to these processes including inferior frontal gyrus (IFG) and superior temporal gyrus (STG) are abnormally activated in individuals that hallucinate. A recent study showed activation in IFG-STG to be modulated by auditory attractiveness, but no study has investigated whether these IFG-STG activations are impaired in schizophrenia. We aimed to clarify the cerebral function underlying the perception of auditory attractiveness in schizophrenia patients. Cerebral activation was examined in 18 schizophrenia patients and 18 controls when performing Favorability Judgment Task (FJT) and Gender Differentiation Task (GDT) for pairs of greetings using event-related functional MRI. A full-factorial analysis revealed that the main effect of task was associated with activation of left IFG and STG. The main effect of Group revealed less activation of left STG in schizophrenia compared with controls, whereas significantly greater activation in schizophrenia than in controls was revealed at the left middle frontal gyrus (MFG), right temporo-parietal junction (TPJ), right occipital lobe, and right amygdala (p < 0.05, FDR-corrected). A significant positive correlation was observed at the right TPJ and right MFG between cerebral activation under FJT minus GDT contrast and the score of hallucinatory behavior on the Positive and Negative Symptom Scale. Findings of hypo-activation in the left STG could designate brain dysfunction in accessing vocal attractiveness in schizophrenia, whereas hyper-activation in the right TPJ and MFG may reflect the process of mentalizing other person's behavior by auditory hallucination by abnormality of cognitive bias.

Cross-cultural differences in the processing of non-verbal affective vocalizations by Japanese and canadian listeners

The Montreal Affective Voices (MAVs) consist of a database of non-verbal affect bursts portrayed by Canadian actors, and high recognitions accuracies were observed in Canadian listeners. Whether listeners from other cultures would be as accurate is unclear. We tested for cross-cultural differences in perception of the MAVs: Japanese listeners were asked to rate the MAVs on several affective dimensions and ratings were compared to those obtained by Canadian listeners. Significant Group × Emotion interactions were observed for ratings of Intensity, Valence, and Arousal. Whereas Intensity and Valence ratings did not differ across cultural groups for sad and happy vocalizations, they were significantly less intense and less negative in Japanese listeners for angry, disgusted, and fearful vocalizations. Similarly, pleased vocalizations were rated as less intense and less positive by Japanese listeners. These results demonstrate important cross-cultural differences in affective perception not just of non-verbal vocalizations expressing positive affect (Sauter et al., 2010), but also of vocalizations expressing basic negative emotions.