What type of cognitive changes are present in individuals with spinal muscular atrophy (SMA) type 3? More so, do these cognitive changes affect clinical factors and, if so, how? According to Neurology Live, researchers sought to more deeply understand the correlation between cognitive and clinical factors in adult patients. 

In a preliminary study, published in Neuromuscular Disorders, researchers evaluated how 22 individuals with SMA type 3 compared to a group of healthy controls. During the study, researchers evaluated executive function, language and visuospatial capabilities, and memory, as well as tests associated with motor skills and function, walking, and muscle strength. Findings from the study show that:

• In many tests, including the Trail Making Test B, individuals with SMA type 3 performed worse than the healthy controls. Some test performances correlated with factors like how old the patients were when their symptoms started or how long they had been living with SMA. 
• Lower test performances, including those regarding language, correlated more with symptom onset than the duration of the disease.
• The cognitive performance correlated to motor function in males. However, this same correlation was not found for females.

Ultimately, though the researchers found that those with SMA type 3 have cognitive changes linked to motor function, they are unsure how often poorer cognition is associated with the condition or what alters cognitive function. They hypothesize potential intrinsic brain pathology, but more research is needed to be sure.

About Spinal Muscular Atrophy (SMA) 

Spinal muscular atrophy (SMA) is a rare genetic disorder caused by SMN1 gene mutations. SMN1 mutations cause the loss of motor neurons in the brainstem and spinal cord. As these motor neurons are lost, muscle function and strength is impaired. Thus, SMA causes muscle atrophy and progressive muscle weakness.

Altogether, there are four main subtypes of SMA. The first form is the most severe, diagnosed at or quickly following birth, while SMA types 3 and 4 tend to be milder in nature. SMA type 3, the form discussed in this article, is also known as Kugelberg-Welander syndrome. It typically presents with symptoms such as mild muscle weakness, frequent respiratory infections, poor balance, and difficulty walking and standing.

Learn more about the different types of SMA and related symptoms.