Sensory symptoms common in fragile X, seen to affect patients’ daily life: Study

Overreaction to sensory stimuli occurs 'far more frequently' in boys and men

Patricia Inácio, PhD avatar

by Patricia Inácio, PhD |

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Signs of hyperarousal, or overreactions to sensory stimuli, and abnormal processing of sensory information — including difficulty with eye gaze and sensitivity to touch and certain sounds — are highly prevalent among people with fragile X syndrome, a new study reports.

Such overreactions and resulting behavioral difficulties were found to occur “far more frequently in males, which is consistent with males with [fragile X] being more affected,” the researchers wrote.

These symptoms were linked to significantly higher levels of irritability, and impaired a patient’s ability to engage in daily activities.

Managing these issues “requires practical solutions and adaptations to avoid distressing reactions,” the team wrote.

The study, “Sensory Symptoms and Signs of Hyperarousal in Individuals with Fragile X Syndrome: Findings from the FORWARD Registry and Database Multisite Study,” was published in the Journal of Autism and Developmental Disorders.

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Researchers note lack of data on sensory symptoms, hyperarousal

Fragile X syndrome is caused by low or no levels of the FMRP protein due to mutations in the FMR1 gene. An FMRP deficiency impairs nerve cell communication, leading to a variety of behavioral and developmental symptoms.

“Closely linked to these behavioral problems are sensory symptoms (SS) and hyperarousal (HA),” the researchers wrote.

Sensory symptoms, concerning problems in the processing and integration of information that comes in through the senses, may include sensitivity to sounds, clothing, light touch, movement, and food.

Signs of hyperarousal, defined as heightened bodily and mental responses to sensory input, may include feeling easily overwhelmed and upset, and having an inability to regulate emotions. This can lead to frequent outbursts, aggressive behavior, and social anxiety, among other issues.

“It appears that in [fragile X syndrome], the influx of sensory stimulation may serve to kindle heightened physiological and emotional reactivity and responsivity, resulting in overarousal or HA [hyperarousal] and further increasing sensory over responding,” the researchers wrote.

Despite their high frequency among fragile X patients, however, sensory symptoms and hyperasousal “have not been characterized to the same extent as other behavioral features,” the researchers noted.

It appears that in [fragile X syndrome], the influx of sensory stimulation may serve to kindle heightened physiological and emotional reactivity and responsivity, resulting in overarousal or HA [hyperarousal] and further increasing sensory over responding.

With this in mind, a team led by scientists at the Duke University Health System, in North Carolina, and the University of California, San Francisco analyzed data from the Fragile X Online Registry with Accessible Research Database (FORWARD), a natural history study of fragile X.

FORWARD collected data from 1,070 patients followed from 2012 to 2017 at 25 U.S. Fragile X Clinical and Research Consortium Clinics.

The researchers analyzed clinician responses to 10 questions concerning sensory symptoms, signs of hyperarousal, their impact on daily activities, and treatment. Potential links were assessed between these symptoms and abnormal behaviors, using with the caregiver-reported Aberrant Behavior Checklist-Community (ABC-C) test.

A total of 933 patients — 720 males and 213 females — had available data for all measures. Their mean age at clinical evaluation was 12.2 years, and they were mainly non-Hispanic white individuals (79%). A total of 11% were Hispanic/Latino patients, and about 8% were Black/African American individuals.

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90% of boys ages 4-12 found to have sensory symptoms

Regarding behaviors related to sensory symptoms and hyperarousal, the ones most commonly reported by clinicians were anxiety, affecting 81% of patients, followed by attention problems (79%) and hypersensitivity/overreaction to stimuli/emotionally reactive (69%).

Compared with female patients, a greater proportion of males were diagnosed with autism spectrum disorder (47% vs. 19%) and were on medications to control abnormal behaviors (67% vs. 56%).

From infancy to early teens, most of both male and female patients were reported to experience sensory symptoms and signs of hyperarousal.

However, sensory symptoms were experienced by a significantly higher proportion of males (87% vs. 68%).

Nearly all boys between the ages of 4 and 12 had sensory symptoms (90%) compared with 71% of age-matched girls. From 13 years onward, sensory symptoms were less prevalent, both in boys (32%) and girls (16%).

Signs of hyperarousal also were significantly more frequent among males than females (92% vs. 79%), and showed an age-related dynamic similar to that seen for sensory symptoms.

“Males were also more severely impacted” by sensory symptoms or hyperarousal, the team wrote, as a greater proportion of them were reported to experience such problems often or always relative to females.

Hypersensitivity, overreaction, and emotionally reactive behavior was reported in 73% of male and 54% of female patients.

Unusual sensory behaviors, such as flaps of hands and hand bites, also were common and significantly more frequent among males relative to females (89% vs. 57%). While their frequency was relatively stable over time in boys, it increased in girls between the ages of 4 and 12, after which it showed a sharp reduction.

Regarding sensory symptoms, the most prevalent was difficulties with eye gaze, affecting 56% of males and 46% of females. Reaching adolescence, these difficulties became more frequent in boys (65%) and girls (56%).

This was followed by sensitivity to certain sounds — experienced by 59% of males and 42% of females — and sensitivity to touch, also known as tactile defensiveness, which affected 46% of males and 34% of females. Less frequent symptoms, without significant differences between sexes, were excessive fear of movement (17%) and difficulty with sensitivity to bright lights (11%).

In addition, “hypersensitivity/overreaction to stimuli/emotionally reactive behaviors were a limiting problem for the child/family 48% of the time for males and 36% for females,” the team wrote. Meanwhile sensory symptoms or hyperarousal “restricted participation in everyday activities 74% of the time for males and 50% for females,” they noted.

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Treatment for sensory problems less frequent after age 12

The researchers noted that 48% of all patients were being treated for sensory problems, most commonly with occupational therapy and physical therapy (44% of all patients). These non-medication therapies became less frequent after 12 years of age — down to 24% of males and 9% of females — which may be due to the “lack of available services in the school system, high cost of private services, and/or perceived lack of effectiveness,” the researchers wrote.

In contrast, the use of psychopharmacological or investigational medications increased with age, with 81% of boys ages 7 and older, and 69.6% of girls at age 13 being on such treatments.

Having a strong sensory response was found to be significantly associated with more behavioral problems, such as hypersensitivity/overreaction to stimuli, irritability/aggression, and anxiety.

It also was significantly linked to more severe intellectual disability, and greater irritability in the ABC-C scale, in both boys and girls.

Multiple statistical analyses suggested that sensory symptoms and signs of hyperarousal were significantly associated with increased irritability and greater imitations in patients’ ability to participate in everyday activities.

Overall, these findings support sensory symptoms and hyperarousal “as core neurodevelopmental [features of fragile X], but more research is needed to fully understand their characteristics, associations, treatment, and impact on individuals with the disorder,” the team concluded.