Study Links Autism Spectrum Disorders, Including Fragile X, to Low Cholesterol Levels

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by Alice Melão |

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Similar to people with fragile X syndrome, those with autism spectrum disorder (ASD) have low blood levels of cholesterol compared to healthy individuals, a study suggests.

The findings indicate that having ASD and low cholesterol levels increase the risks for intellectual disability and anxiety/depression.

Although additional studies are still needed to better understand the implications of low cholesterol levels in this group, this study’s findings also suggest that such low levels could be a biomarker of ASD, the investigators said.

The study, “Implication of hypocholesterolemia in autism spectrum disorder and its associated comorbidities: A retrospective case–control study,” was published in the journal Autism Research.

ASD is an umbrella term used for conditions characterized by deficits in social communication and restricted, repetitive patterns of behavior and interests. Despite the increasing incidence of ASD, its underlying biological processes remain poorly understood.

Fragile X is the leading genetic cause of autism, with up to 60% of people with fragile X meeting the criteria of ASD. Indeed, about 33% of children with fragile X cannot be distinguished from children of the same age with ASD, in terms of clinical symptoms such as gaze avoidance, repetitive behavior, and sensory deficits.

Studies have revealed low levels of cholesterol (or hypocholesterolemia) in people with fragile X, which could result from altered cholesterol metabolism due to the absence of fragile X mental retardation protein (FMRP) — the hallmark feature of this condition. Studies in ASD have reported similar findings, but this connection needs more research.

Researchers from the Université de Sherbrooke, in Canada, addressed this knowledge gap by reviewing the clinical records of 79 individuals with ASD (average age 19.4 years, 81% males) who had been diagnosed between 2007 and 2017 at the CIUSSS de l’Estrie-CHU, in Quebec. Blood levels of total cholesterol, triglycerides, LDL and HDL were compared to those of 79 healthy controls.

Among people with ASD, 75% had at least one developmental condition, 32% had been diagnosed with a medical problem, and 61% had psychiatric/behavioral issues. Only nine (11%) of ADS individuals did not have any associated condition, and 13 patients (16%) had fragile X or another genetic disorder.

Results showed significantly lower levels of total cholesterol, HDL and LDL in people with ASD compared to the controls. These differences were mostly noted among males with ADS.

Low levels of cholesterol were more than three times more frequent in the ASD group than in the general population, indicating it could be a potential biomarker of ASD.

One patient with genetically confirmed FXS showed significantly low levels of total cholesterol. However, no significant differences in lipid profiles were found in the overall group with a genetic condition compared with those without genetic disorders.

Compared to the controls, the risk of intellectual disability linked to ADS was 3.33 times higher in people with low levels of total cholesterol. Likewise, ASD-associated anxiety/depression was 4.74-times more prevalent in this group.

“Our results support an association between hypocholesterolemia and ASD, and open novel opportunities for the diagnosis and treatment of specific forms of ASD,” the researchers wrote.