The Autism Phenome Project: Toward Identifying Clinically Meaningful Subgroups of Autism

One of the most universally accepted facts about autism is that it is heterogenous. Individuals diagnosed with autism spectrum disorder have a wide range of behavioral presentations and a variety of co-occurring medical and mental health conditions. The identification of more homogenous subgroups is likely to lead to a better understanding of etiologies as well as more targeted interventions and treatments. In 2006, we initiated the UC Davis MIND Institute Autism Phenome Project (APP) with the overarching goal of identifying clinically meaningful subtypes of autism. This ongoing longitudinal multidisciplinary study now includes over 400 children and involves comprehensive medical, behavioral, and neuroimaging assessments from early childhood through adolescence (2-19 years of age). We have employed several strategies to identify sub-populations within autistic individuals: subgrouping by neural, biological, behavioral or clinical characteristics as well as by developmental trajectories. In this Mini Review, we summarize findings to date from the APP cohort and describe progress made toward identifying meaningful subgroups of autism.

Trait Mindfulness at Baseline Predicts Increases in Telomerase Activity Over Time

Introduction.

Preliminary investigations of cross-sectional samples have linked trait mindfulness with measures related to the hypothalamic–pituitary–adrenal (HPA)-mediated stress response and to the inflammatory system, suggesting that this is one potential pathway linking mindfulness based interventions and health. However, no previous studies explored the association between the trait mindfulness construct and markers of cellular ageing.

Methods.

In the current study we examined in a sample of healthy mothers (n = 92) of a child with Autism Spectrum Disorder (i.e. women showing high levels of chronic psychological stress) the prospective associations between a multidimensional scale of trait mindfulness, the Five Facet Mindfulness Questionnaire (FFMQ), and telomerase activity (TA), a marker of cellular ageing and telomere homeostasis. Participants’ trait mindfulness and TA were assessed at baseline as well as 9 and 18 month follow-up.

Results.

Analysis showed that higher levels of baseline mindfulness on FFMQ observation and describe subscales were related to increase in TA from baseline to 9 month (r = 0.27, P = 0.03 and r = 0.24, P = .04, respectively). Additionally, the FFMQ Describe subscale was related to increase in TA from baseline to 18 month (r = .30, P = .02). Results are reported following covariate adjustment of age, BMI, ethnicity, and education.

Discussion.

Our results showed that higher levels of baseline mindfulness are associated with higher increases in TA after 9 months and 18 months, with increased TA reportedly being associated with decreased oxidative damage, increased telomere length and overall more functional cellular physiology. These findings support a role of mindfulness-related interventions to increase general and mental health.

Disclosure of interest

The authors have not supplied their declaration of competing interest.

Speech and Span: Working Memory Capacity Impacts the Use of Animacy but Not of World Knowledge during Spoken Sentence Comprehension

We present results from a study demonstrating that high- and low-span listeners show qualitatively different brain responses when comprehending simple active sentences. Participants listened to naturally produced sentences in three conditions in which the plausibility of thematic relations was manipulated, for instance: The dog(1)/The poet(2)/The box(3) is biting the mailman. Event-related potentials were recorded to the first noun, the verb, and the second noun in all three conditions. In (2), the thematic relations between the words in the sentence are less expected given our world knowledge, and this resulted in an N400 effect of semantic processing difficulty to the second noun for both high- and low-span subjects. In (3), the inanimate first noun cannot be the agent of the verb. Only high-span subjects showed an effect of animacy on the sentence-initial nouns, evident from a larger anterior negative shift to inanimate than animate nouns. Furthermore, to the thematically violated verbs (3), low-span subjects showed an N400, whereas high-span subjects generated a P600. We suggest that this P600 effect to the thematically violated verb may be related to processing costs resulting from a conflict between the provisional thematic roles assigned as a function of the inanimate sentence-initial noun, and the actual (animate) agent required by the verb. We further argue that low-span subjects lag behind those with high span in their use of animacy, but not real-world knowledge in the on-line computation of thematic roles in spoken language comprehension.

Reaction time measures of interhemispheric transfer time in reading disabled and normal children

This experiment was designed to test whether reading disabled boys differ from matched controls on behavioral measures of interhemispheric transfer time (IHTT). Specifically, we proposed that language-disordered reading disabled children who had deficits in naming would show either faster or slower IHTTs compared with controls. From an initial group of 118 right-handed males, we selected a group of 25 disabled and 25 normal readers, matched on age. All subjects had to obtain a full scale IQ of 90 or above, a PIQ score of 85 or above, and a scaled score of 7 or above on the Block Design Subtest of the WISC-R. After meeting additional criteria for group assignment, manual reaction time (RT) measures of IHTT were obtained in response to simple visual and tactile stimuli during two laboratory testing sessions. Half the trials were conducted with the hands in an uncrossed orientation and half with the hands crossed in order to examine the effects of spatial compatibility on estimates of IHTT. The results revealed no overall group differences in IHTT for any of the conditions. However, correlations between IHTT measures and indices of cognitive performance indicated that faster IHTTs were significantly correlated with poorer performance on measures of reading and language function in the dyslexic group. These data are discussed within the context of a model of interhemispheric transfer deficits in disabled readers.

Ratings of emotion in faces are influenced by the visual field to which stimuli are presented

This experiment was designed to assess the differential impact of initially presenting affective information to the left versus right hemisphere on both the perception of and response to the input. Nineteen right-handed subjects were presented with faces expressing happiness and sadness. Each face was presented twice to each visual field for an 8-sec duration. The electro-oculogram (EOG) was monitored and fed back to subjects to train them to keep their eyes focused on the central fixation point as well as to eliminate trials confounded by eye movement artifact. Following each slide presentation, subjects rated the intensity of the emotional expression depicted in the face and their emotional reaction to the face on a series of 7-point rating scales. Subjects reported perceiving more happiness in response to stimuli initially presented to the left hemisphere (right visual field) compared to presentations of the identical faces to the right hemisphere (left visual field). This effect was predominantly a function of ratings on sad faces. A similar, albeit less robust, effect was found on self-ratings of happiness (the degree to which the face elicited the emotion in the viewer). These data challenge the view that the right hemisphere is uniquely involved in all emotional behavior. The implications of these findings for theories concerning the lateralization of emotional behavior are discussed.

Cross-cultural differences in hemisphericity: EEG asymmetry discriminates between Japanese and Westerners

This study was designed to test the hypothesis that Japanese subjects exhibit different patterns of resting EEG asymmetry compared with Westerners. EEG was recorded from the left and right temporal and parietal scalp regions in bilingual Japanese and Western subjects during eyes-open and eyes-closed rest periods before and after the performance of a series of cognitive tasks. Alpha activity was integrated and digitized. Japanese subjects were found to exhibit greater relative right-sided parietal activation during the eyes closed condition. This difference was found to be a function of greater left hemisphere activation among the Westerners. Various possible contributors to this cross-cultural differences are discussed.

Frontal and parietal electroencephalogram asymmetry in depressed and nondepressed subjects

High vs. low scorers on the Beck Depression Inventory (BDI) were compared on measures of resting EEG activation asymmetry from frontal and parietal brain regions. Depressed subjects showed greater relative right frontal activation compared with nondepressed subjects. Parietal asymmetry did not distinguish between the groups. These data support the hypothesis of right hemisphere hyperactivation in the frontal region of depressed individuals and are consistent with the growing body of literature which suggests that the left and right frontal regions may be differentially specialized for particular positive and negative affects.

Effects of personality and semantic content of stimuli on augmenting and reducing in the event-related potential

Two groups of subjects classified as high vs. low in the need for power (n power) were assessed for augmenting versus reducing in the event-related potential (ERP) elicited by neutral and power-related words. Words at four different intensity levels in each of these two classes were randomly presented and ERPs in response to each word class at each of the four intensity levels were computed from EEG recorded at Fz. The results indicated that the two groups responded differentially to the power-related vs. neutral words. HIgh n power subjects showed reduction in response to both power-related and neutral words while low n power subjects showed augmentation in response to the power-related words.

Stressed power motivation, sympathetic activation, immune function, and illness

Previous research has reported that individuals high in the need for Power, high in inhibition, and high in power stress (the HHH group) are more likely than other individuals to report more severe illnesses. The present study investigates the possibility that the mechanism underlying this relationship is greater sympathetic activation in the HHH group which has an immunosuppressive effect. College males with the HHH syndrome reported more frequent and more severe illnesses than other individuals, as in previous studies. More of the HHH than other subjects also showed above average epinephrine excretion rates in urine and below average concentrations of immunoglobulin A in saliva (S-IgA). Furthermore, higher rates of epinephrine excretion were significantly associated with lower S-IgA concentrations, and lower S-IgA concentrations were significantly associated with reports of more frequent illnesses. The findings are interpreted as consistent with the hypothesis that a strong need for Power, if it is inhibited and stressed, leads to chronic sympathetic overactivity which has an immunosuppressive effect making individuals characterized by this syndrome more susceptible to illness.

The need for power, brain norepinephrine turnover and learning

This experiment was designed to explore whether brain norepinephrine (NE) serves as a specific reward system for the power drive. Previous research has indicated that 3-methoxy-4-hydroxyphenyl glycol (MHPG), a urinary metabolite reflecting central NE turnover, is positively correlated with features of assertiveness which one might expect of a person high in the need for power (n power) or in a state of aroused power motivation. Twenty-seven male undergraduates, 13 of whom were high and 14 of whom were low in n power as assessed by a TAT measure, were recruited as subjects. Before and after the laboratory session, subjects voided all urine and concentrations of epinephrine, norepinephrine and MHPG were obtained from samples. The laboratory task consisted of 20 picture-word pairs in which the subject had to learn to anticipate the word associated with each picture before the word was presented. Five pairs of stimuli in each of the following picture-word combinations were presented 12 times: neutral-neutral, neutral-power, power-neutral and power-power. The results revealed that, as predicted, subjects high in n power learn most power-related material faster than subjects low in n power. The need for achievement is unrelated to the learning of any picture-word pairs. The neurochemical data indicated that subjects maintaining a relatively high MHPG excretion rate during the experiment who were also high in n power showed the greatest mastery of power related compared with neutral picture-word pairs. These findings are consistent with the hypothesis that brain NE turnover is specifically related to the learning of power-related responses in subjects high in n power.