"I Do Not Know How You Feel and How I Feel About That": Mentalizing Impairments in Machado-Joseph Disease

Machado Joseph disease (MJD), also known as spinocerebellar ataxia type 3 (SCA3), is an autosomal dominant neurodegenerative disease. Mentalizing is the ability to think and understand the mental state of the other and of the self in terms of thoughts, feelings, and intentions. The aim of this study is to fill the gap in our understanding of mentalizing in MJD since there is currently very little and inconsistent research on MJD and mentalizing. A total of 18 Jews of Yemenite origin with clinically and genetically confirmed MJD, 5 pre-symptomatic MJD with a positive genetic test, and 17 Jews of Yemenite origin healthy controls, underwent a battery of tests consisting of reading the mind in the eyes (RME), Toronto Alexithymia Scale (TAS-20), and false belief test (FBt). The MJD group scored lower on the RME and FBt, and higher on TAS-20 test compared to control. A significant negative correlation was found between disease duration and RME score. All the pre-symptomatic participants scored within the normal clinical range in all tests. MJD patients demonstrated a widespread deficiency in the ability to mentalizing on a clinical level with autistic characteristics. These impairments may impact the patient's interpsychic experience and daily life interactions and have important clinical implication. Pre-symptomatic participants demonstrated normal mentalizing in all tests, suggesting that the mentalizing impairments do not precede the symptoms of ataxia and are part of the clinical picture of MJD.