A variation in the infant oxytocin receptor gene modulates infant hippocampal volumes in association with sex and prenatal maternal anxiety.

Genetic variants in the oxytocin receptor (OTR) have been linked to distinct social phenotypes, psychiatric disorders and brain volume alterations in adults. However, to date, it is unknown how OTR genotype shapes prenatal brain development and whether it interacts with maternal prenatal environmental risk factors on infant brain volumes. In 105 Finnish mother-infant dyads (44 female, 11-54 days old), the association of offspring OTR genotype rs53576 and its interaction with prenatal maternal anxiety (revised Symptom Checklist 90, gestational weeks 14, 24, 34) on infant bilateral amygdalar, hippocampal and caudate volumes were probed. A sex-specific main effect of rs53576 on infant left hippocampal volumes was observed. In boys compared to girls, left hippocampal volumes were significantly larger in GG-homozygotes compared to A-allele carriers. Furthermore, genotype rs53576 and prenatal maternal anxiety significantly interacted on right hippocampal volumes irrespective of sex. Higher maternal anxiety was associated both with larger hippocampal volumes in A-allele carriers than GG-homozygotes, and, though statistically weak, also with smaller right caudate volumes in GG-homozygotes than A-allele carriers. Our study results suggest that OTR genotype enhances hippocampal neurogenesis in male GG-homozygotes. Further, prenatal maternal anxiety might induce brain alterations that render GG-homozygotes compared to A-allele carriers more vulnerable to depression.

Partial Support for an Interaction Between a Polygenic Risk Score for Major Depressive Disorder and Prenatal Maternal Depressive Symptoms on Infant Right Amygdalar Volumes.

Psychiatric disease susceptibility partly originates prenatally and is shaped by an interplay of genetic and environmental risk factors. A recent study has provided preliminary evidence that an offspring polygenic risk score for major depressive disorder (PRS-MDD), based on European ancestry, interacts with prenatal maternal depressive symptoms (GxE) on neonatal right amygdalar (US and Asian cohort) and hippocampal volumes (Asian cohort). However, to date, this GxE interplay has only been addressed by one study and is yet unknown for a European ancestry sample. We investigated in 105 Finnish mother-infant dyads (44 female, 11-54 days old) how offspring PRS-MDD interacts with prenatal maternal depressive symptoms (Edinburgh Postnatal Depression Scale, gestational weeks 14, 24, 34) on infant amygdalar and hippocampal volumes. We found a GxE effect on right amygdalar volumes, significant in the main analysis, but nonsignificant after multiple comparison correction and some of the control analyses, whose direction paralleled the US cohort findings. Additional exploratory analyses suggested a sex-specific GxE effect on right hippocampal volumes. Our study is the first to provide support, though statistically weak, for an interplay of offspring PRS-MDD and prenatal maternal depressive symptoms on infant limbic brain volumes in a cohort matched to the PRS-MDD discovery sample.

Associations of age and sex with brain volumes and asymmetry in 2-5-week-old infants.

Information on normal brain structure and development facilitates the recognition of abnormal developmental trajectories and thus needs to be studied in more detail. We imaged 68 healthy infants aged 2-5 weeks with high-resolution structural MRI (magnetic resonance imaging) and investigated hemispheric asymmetry as well as the associations of various total and lobar brain volumes with infant age and sex. We found similar hemispheric asymmetry in both sexes, seen as larger volumes of the right temporal lobe, and of the left parietal and occipital lobes. The degree of asymmetry did not vary with age. Regardless of controlling for gestational age, gray and white matter had different age-related growth patterns. This is a reflection of gray matter growth being greater in the first years, while white matter growth extends into early adulthood. Sex-dependent differences were seen in gray matter as larger regional absolute volumes in males and as larger regional relative volumes in females. Our results are in line with previous studies and expand our understanding of infant brain development.

Illuminating the clinical significance of alexithymia subtypes: A cluster analysis of alexithymic traits and psychiatric symptoms.

BACKGROUND: Alexithymia is a personality construct involving difficulties identifying and verbalizing feelings, and an externally oriented thinking style. There is preliminary evidence for alexithymia subtypes that may carry different risk profiles for psychiatric illness. The aim of this study was to gain support for the existence of alexithymia subtypes and further characterize their clinical relevance. METHODS: To identify possible subtypes, a cluster analysis was conducted for individuals with high alexithymic traits (N=113). Current depressive and anxiety symptoms, self-reported psychiatric medical history, and self-reported early life adversity were compared between subtypes. The cluster analysis was replicated with the low (N=2471) and moderate (N=290) alexithymia groups. RESULTS: We identified two alexithymia subtypes. Compared to type A, type B alexithymia was associated with higher levels of difficulties in identifying feelings, and was more strongly associated with current depressive (Cohen's d=0.77, p<0.001) and anxiety symptoms (Cohen's d=0.82, p<0.001), and self-reported early life adversity (Cohen's d 0.42, p=0.048). Compared to type A, type B alexithymia was also associated with a higher prevalence of self-reported diagnosis of major depressive- (30.2% vs. 8.3%) and anxiety disorder (18.9% vs. 3.3%). CONCLUSIONS: The results of this study support the hypothesis of alexithymia subtypes, and add support to the growing evidence showing that alexithymia is likely a heterogeneous and dimensional phenomenon. The subtype (type B) with most pronounced difficulties in identifying feelings may be associated with a higher risk for psychiatric illness compared to type A alexithymia, and may exhibit a more severe history of early life adversity.

Adaption of pregnancy anxiety questionnaire-revised for all pregnant women regardless of parity: PRAQ-R2.

The 10-item Pregnancy-Related Anxiety Questionnaire-Revised (PRAQ-R) is a widely used instrument to assess and identify pregnancy-specific anxiety in nulliparous women. It has good psychometric values and predictive validity for birth and childhood outcomes. Nonetheless, the PRAQ-R is not designed for use in parous women, as particularly one item of the questionnaire is not relevant for women who gave birth before. We tested the factorial and scalar invariance of a modified PRAQ-R2 across nulliparous and parous women with an adapted item to fit both groups of pregnant women. A longitudinal study among 1144 pregnant women (n = 608 nulliparous and n = 536 parous) with two repeated measures of the PRAQ-R2 was used to test for measurement invariance of the instrument. Results show metric and scalar invariance, indicating that the PRAQ-R2 measures similar constructs on the same scale for all pregnant women at two different times during pregnancy. We conclude that the PRAQ-R2 can be used, compared, or combined in a sample of nulliparous and parous women.

Five-year follow-up of 11C-PIB uptake in Alzheimer's disease and MCI.

PURPOSE: The aim of this study was to evaluate the longitudinal changes in [(11)C]PIB uptake in mild cognitive impairment (MCI) and Alzheimer's disease (AD) over a long-term follow-up. METHODS: Six AD patients, ten MCI patients and eight healthy subjects underwent a [(11)C]PIB PET scan at baseline and at 2 and 5 years. The clinical status of the MCI patients was evaluated every 6 months. RESULTS: The MCI group showed a significant increase in [(11)C]PIB uptake over time (p < 0.001), with a similar increase from baseline to 2 years (4.7% per year) and from 2 to 5 years (5.0% per year). Eight MCI patients (80%) converted to AD, and two of these patients showed a normal [(11)C]PIB scan at baseline but increased uptake later. There was an increase in [(11)C]PIB uptake with time in the AD group (p = 0.02), but this did not significantly differ from the change in the control group. CONCLUSION: Our results revealed a significant increase in amyloid load even at the time of AD diagnosis in some of the MCI patients who converted. A positive [(11)C]PIB scan at baseline in MCI patients strongly predicted future conversion to AD but a negative PIB scan in MCI patients did not exclude future conversion. The results suggest that there is wide individual variation in the brain amyloid load in MCI, and in the course of amyloid accumulation in relation to the clinical diagnosis of AD.

[11C]PIB, [18F]FDG and MR imaging in patients with mild cognitive impairment.

PURPOSE: Cortical glucose metabolism, brain amyloid ß accumulation and hippocampal atrophy imaging have all been suggested as potential biomarkers in predicting which patients with mild cognitive impairment (MCI) will convert to Alzheimer's disease (AD). The aim of this study was to compare the prognostic ability of [(11)C]PIB PET, [(18)F]FDG PET and quantitative hippocampal volumes measured with MR imaging in predicting conversion to AD in patients with MCI. METHODS: The study group comprised 29 patients with MCI who underwent [(11)C]PIB PET and MR imaging. Of these, 22 also underwent [(18)F]FDG PET. All subjects were invited back for clinical evaluation after 2 years. RESULTS: During the follow-up time 17 patients had converted to AD while 12 continued to meet the criteria for MCI. The two groups did not differ in age, gender or education level, but the converter group tended to have lower MMSE and Word List learning than the nonconverter group. High [(11)C]PIB retention in the frontotemporal regions and anterior and posterior cingulate (p < 0.05) predicted conversion to AD. Also reduced [(18)F]FDG uptake in the left lateral temporal cortex (LTC) predicted conversion (p < 0.05), but quantitative hippocampal volumes did not (p > 0.1). In receiver operating characteristic (ROC) analysis the measurements that best predicted the conversion were [(11)C]PIB retention in the lateral frontal cortex and [(18)F]FDG uptake in the left LTC. Both PET methods resulted in good sensitivity and specificity and neither was significantly superior to the other. CONCLUSION: The findings indicate that [(11)C]PIB and [(18)F]FDG are superior to hippocampal volumes in predicting conversion to AD in patients with MCI.

Early detection of Alzheimer disease: ¹¹C-PiB PET in twins discordant for cognitive impairment.

OBJECTIVE: The aim of this study was to investigate whether cognitively preserved monozygotic or dizygotic cotwins of persons with Alzheimer disease (AD) exhibit increased brain amyloid accumulation. METHODS: We performed a cross-sectional carbon-11 labeled 2-(4'-methylaminophenyl)-6-hydroxybenzothiazole ((11)C)-Pittsburgh compound B (PiB) PET study on 9 monozygotic and 8 dizygotic twin pairs discordant for cognitive impairment as well as on 9 healthy elderly control subjects. (11)C-PiB uptake was analyzed with Statistical Parametric Mapping and with region of interest analysis with the region-to-cerebellum ratio as a measure of tracer uptake. RESULTS: Cognitively preserved monozygotic cotwins of cognitively impaired probands had increased cortical (11)C-PiB uptake (117%-121% of control mean) in their temporal and parietal cortices and the posterior cingulate. Cognitively preserved dizygotic subjects did not differ from the controls. Further, the cognitively preserved monozygotic subjects showed similar (11)C-PiB uptake patterns as their cognitively impaired cotwins. The cognitively impaired subjects (monozygotic and dizygotic individuals combined) showed typical Alzheimer-like patterns of (11)C-PiB uptake. CONCLUSIONS: Genetic factors appear to influence the development of Alzheimer-like ß-amyloid plaque pathology. The dissociation between cognitive impairment and brain ß-amyloidosis in monozygotic twins implies that there may be important environmental/acquired factors that modulate the relationship between brain amyloidosis and neurodegeneration. AD may be detectable in high-risk individuals in its presymptomatic stage with (11)C-PiB PET, but clinical follow-up will be needed to confirm this.

Follow-up of [11C]PIB uptake and brain volume in patients with Alzheimer disease and controls.

OBJECTIVE: In Alzheimer disease (AD), the accumulation pattern of beta-amyloid over time and its relationship with dementia severity are unclear. We investigated the brain uptake of the amyloid ligand (11)C-labeled Pittsburgh compound B ([(11)C]PIB) and volumetric brain changes over a 2-year follow-up in patients with AD and in aged healthy controls. METHODS: Fourteen patients with AD (mean age 72 years, SD 6.6) and 13 healthy controls (mean age 68 years, SD 5.4) were examined at baseline and after 2 years (patients with AD: mean 2.0 years, SD 0.2; controls: mean 2.1 years, SD 0.6) with [(11)C]PIB PET, MRI, and neuropsychological assessments. [(11)C]PIB uptake was analyzed with a voxel-based statistical method (SPM), and quantitative data were obtained with automated region-of-interest analysis. MRI data were analyzed with voxel-wise tensor-based morphometry. RESULTS: The [(11)C]PIB uptake of the patients with AD did not increase significantly during follow-up when compared with that of the controls. MRI showed progressive brain volume change in the patients with AD, e.g., in the hippocampal region, temporal cortex, and precuneus (p < 0.05). The mean Mini-Mental State Examination score of the patients with AD declined from 24.3 (SD 3.1) at baseline to 21.6 (SD 3.9) at follow-up (p = 0.009). Cognitive decline was also evident in other neuropsychological test results. Baseline neocortical [(11)C]PIB uptake ratios predicted subsequent volumetric brain changes in the controls (r = 0.725, p = 0.005). CONCLUSIONS: The results suggest no (or only little) increase in (11)C-labeled Pittsburgh compound B ([(11)C]PIB) uptake during 2 years of Alzheimer disease progression, despite advancing brain atrophy and declining cognitive performance. Nevertheless, changes in [(11)C]PIB uptake during a longer follow-up cannot be excluded. High cortical [(11)C]PIB uptake may predict ongoing brain atrophy in cognitively normal individuals.