Children with autism have memory challenges that hinder not only their memory for faces but also their ability to remember other kinds of information, according to new research from the Stanford School of Medicine. These impairments are reflected in distinct wiring patterns in the children’s brains, the study found.
The research, which was published July 10 inBiological Psychiatry: Cognitive Neuroscience and Neuroimaging, clarifies a debate about memory functioninkids with autism, showingthat their memory strugglessurpasstheir ability to form social memories. The finding should prompt broader thinking about autism in childrenand abouttreatment of the developmental disorder, according to the scientists who conducted the study.
“Many high-functioning kids with autism go to mainstream schools andreceivethe same instruction as other kids,” said lead authorJin Liu, PhD, a postdoctoral scholar in psychiatry and behavioral sciences. Memory is a key predictor of academic success,saidLiu, adding thatmemory challengesmay put kids with autism at a disadvantage in school.
The study’s findings alsoraise a philosophical debate about the neural origins of autism, the researchers said. Social challenges are recognized as a core feature of autism, but it’s possible thatmemory impairments might significantly contribute tothe ability to engagesocially.
“Social cognitioncannotoccur withoutreliablememory,” said senior authorVinod Menon, PhD, the Rachael L. and Walter F. Nichols, MD, Professor and a professor of psychiatry and behavioral sciences.
“Social behaviors are complex, and they involve multiplebrainprocesses, includingassociatingfaces and voices to particular contexts, which requirerobustepisodic memory,” Menon said. “Impairments informingtheseassociative memory traces could form one of the foundational elements inautism.”
Comprehensive memory tests
Autism, which affects aboutone in every 36kids, is characterized by social impairments and restricted, repetitive behaviors. The condition exists on a wide spectrum. The most severely affected individuals cannot speak or care for themselves, and about one-third of people with autism have intellectual impairments. On the other end of the spectrum, many people with high-functioning autism have normal or high IQ, complete higher education andworkin a variety of fields.
Researchhasshownthat children with autism have difficulty remembering faces. Some researchhasalso suggested that children with autism have broader memory difficulties, but these studies were small and did not thoroughly assess participants’ memory abilities. They included children with wide ranges of age and IQ, both of which influence memory.
To clarify the impact of autism on memory, the new study included 25 children with high-functioning autism and normal IQ who were 8 to 12 yearsold, and a control group of 29 typically developing children with similar ages and IQs.
All participants completed a comprehensive evaluation of their memory skills, including their ability to remember faces;written material; and non-social photographs, or photos without any people. The scientists tested participants’ability to accurately recognize information (identifying whether they had seen an image or heard a wordbefore)and recallit(describingor reproducing details of information theyhad seenor heard before).Theresearchers testedparticipants’ memory after delays of varying lengths.All participants also received functional magnetic resonance imaging scans of their brains to evaluatehowregions known to beinvolved inmemoryare connected to each other.
Distinct brainnetworks drive memory challenges
In line with prior research, children with autism had more difficulty remembering faces than typically developing children, the study found.
The research showedthey alsostruggledto recall non-social information. On testsabout sentences they read andnon-socialphotosthey viewed,theirscoresforimmediate and delayed verbal recall, immediate visual recall and delayed verbal recognitionwere lower.
“We thoughtthat behavioral differencesmight be weak because the study participants with autism had fairly high IQ, comparable to typically developingparticipants, but we still observed very obvious general memory impairmentsinthis group,” Liu said.
Among typically developing children, memoryskills wereconsistent:If a child had good memory for faces, he or she was also good at remembering non-social information.
This wasn’t the caseinautism. “Among children with autism, some kidsseem tohave both impairments and some have more severe impairment in one area of memory or the other,” Liu said.
The researchers had not expected this.
“It was a surprisingfinding that these two dimensions of memory are both dysfunctional, in ways that seem to be unrelated—and that maps onto our analysis of the brain circuitry,” Menon said.
The findings suggest that general and face-memory challenges have two underlying sources in the brain whichcontributeto a broader profile of memory impairments in autism.
The brain scans showed that, among the children with autism, distinct brain networks drive different types of memory difficulty.
For children with autism, theability to retain non-social memories was predicted by connections in a network centeredonthe hippocampus—a small structure deep inside the brain that is known toregulatememory.But face memoryin kids with autismwas predictedby a separate set of connectionscentered onthe posterior cingulate cortex,a key region ofthe brain’s default mode network, which has roles in social cognition and distinguishing oneself from other people.
“The findings suggest that general and face-memory challenges have two underlying sources in the brain whichcontributeto a broader profile of memory impairments in autism,” Menon said.
In both networks, the brains of children with autism showed over-connected circuits relative to typically developing children. Over-connectivity—likely due to too little selective pruning of neural circuits—has been found in other studies of brain networks in childrenwithautism.
New autism therapies should account for the breadth of memory difficulties the research uncovered, as well as how these challenges affect social skills,Menon said. “This is important for functioning in the real world and for academic settings.”
Other Stanford authors includedresearch scientistHyesangChang, former postdoctoral fellowLang Chen, research assistants JeremyRudoler,AhmadBelalAl-Zughoul,andJuliaBoramKang,and Clinical Associate ProfessorDaniel Abrams.
The study was funded by the National Institutes of Health (grants HD059205, MH084164, HD094623 and MH121069) and by the Stanford Maternal and Child Health Research Institute.
