Disentangling the autism-anxiety overlap: fMRI of reward processing in a community-based longitudinal study

Up to 40% of youth with autism spectrum disorder (ASD) also suffer from anxiety, and this comorbidity is linked with significant functional impairment. However, the mechanisms of this overlap are poorly understood. We investigated the interplay between ASD traits and anxiety during reward processing, known to be affected in ASD, in a community sample of 1472 adolescents (mean age=14.4 years) who performed a modified monetary incentive delay task as part of the Imagen project. Blood-oxygen-level dependent (BOLD) responses to reward anticipation and feedback were compared using a 2x2 analysis of variance test (ASD traits: low/high; anxiety symptoms: low/high), controlling for plausible covariates. In addition, we used a longitudinal design to assess whether neural responses during reward processing predicted anxiety at 2-year follow-up. High ASD traits were associated with reduced BOLD responses in dorsal prefrontal regions during reward anticipation and negative feedback. Participants with high anxiety symptoms showed increased lateral prefrontal responses during anticipation, but decreased responses following feedback. Interaction effects revealed that youth with combined ASD traits and anxiety, relative to other youth, showed high right insula activation when anticipating reward, and low right-sided caudate, putamen, medial and lateral prefrontal activations during negative feedback (all clusters PFWE<0.05). BOLD activation patterns in the right dorsal cingulate and right medial frontal gyrus predicted new-onset anxiety in participants with high but not low ASD traits. Our results reveal both quantitatively enhanced and qualitatively distinct neural correlates underlying the comorbidity between ASD traits and anxiety. Specific neural responses during reward processing may represent a risk factor for developing anxiety in ASD youth.

Subjective memory complaints in community dwelling healthy older people: the influence of brain and psychopathology

OBJECTIVES

Subjective memory complaints (SMC) are common. We aimed to characterize the relationship between psychiatric illness and white matter disease to SMC in a sample of healthy older people.

MEASUREMENTS

Cognitively normal subjects between 55 and 90 years had age-adjusted and education-adjusted Consortium to Establish a Registry for Alzheimer's disease (CERAD) scores ≤1.5 SD from standard mean. ApoE genotyping was performed using polymerase chain reaction. Sixty subjects (30 SMC, 30 controls) underwent 3T MRI, which was rated by two raters blinded to the diagnosis, for periventricular (PVH) and deep white matter hyperintensities (DWMH) using the Fazekas scale. Subjective memory was assessed by asking the participant, Do you feel like your memory or thinking is becoming worse?

RESULTS

Two hundred and fifteen volunteers were assessed. Ninety-six were cognitively normal (mean age 62.5 years). SMC were reported by 52/96 subjects (54%). These were compared with subjects who denied SMC. Participants with a history of depression or anxiety were more likely to have SMC (p = 0.02). The frequency distribution of ApoE4 allele and CERAD scores were similar. White matter load was similar (p ≤ 0.47), with a high prevalence of PVH and DWMH seen (100% and 88% of scans, respectively).

CONCLUSION

Both SMC and white matter disease were common. SMC were associated with a history of depression or anxiety but not with white matter disease. Evaluation for a history of depression and anxiety in people with SMC is supported by these findings.

Functional interactions of the inferior frontal cortex during the processing of words and word-like stimuli

The hypothesis that ventral/anterior left inferior frontal gyrus (LIFG) subserves semantic processing and dorsal/posterior LIFG subserves phonological processing was tested by determining the pattern of functional connectivity of these regions with regions in left occipital and temporal cortex during the processing of words and word-like stimuli. In accordance with the hypothesis, we found strong functional connectivity between activity in ventral LIFG and activity in occipital and temporal cortex only for words, and strong functional connectivity between activity in dorsal LIFG and activity in occipital and temporal cortex for words, pseudowords, and letter strings, but not for false font strings. These results demonstrate a task-dependent functional fractionation of the LIFG in terms of its functional links with posterior brain areas.

The effect of brain atrophy on cerebral hypometabolism in the visual variant of Alzheimer disease

BACKGROUND

Brain glucose metabolic rates measured by positron emission tomography can be more affected by partial volume effects in Alzheimer disease (AD) than in healthy aging because of disease-associated brain atrophy.

OBJECTIVE

To determine whether the distinct distribution of cerebral metabolic lesions in patients with the visual variant of AD (AD + VS) represents a true index of neuronal/synaptic dysfunction or is the consequence of brain atrophy.

SETTING

Government research hospital.

DESIGN

Resting cerebral metabolic rate for glucose was measured with positron emission tomography in a cross-sectional study of AD and AD + VS groups and in healthy control subjects. Segmented magnetic resonance images were used to correct for brain atrophy.

PATIENTS

Patients with AD + VS had prominent visual and visuospatial symptoms. There were 15 patients with AD, 10 with AD + VS, and 37 age-matched control subjects.

MAIN OUTCOME MEASURE

Measurement of the rate of cerebral glucose metabolism.

RESULTS

Before atrophy correction, the AD + VS group, compared with the control subjects, showed hypometabolism in primary and extrastriate visual areas and in parietal and superior temporal cortical areas. Compared with the AD group, the AD + VS group showed hypometabolism in visual association areas. After atrophy correction, hypometabolism remained significantly different between patients and controls and between the 2 AD groups.

CONCLUSIONS

The reductions in cerebral hypometabolism represent a true loss of functional activity and are not simply an artifact caused by brain atrophy. The different patterns of hypometabolism indicate the differential development of the lesions between the AD and AD + VS groups.