Cognitive/personality pattern and triplet expansion size in adult myotonic dystrophy type 1 (DM1): CTG repeats, cognition and personality in DM1.
BACKGROUND
Although central nervous system (CNS) involvement in adult myotonic dystrophy type 1 (DM1) was described long ago, the large number of variables affecting the cognitive and personality profile have made it difficult to determine the effect of DM1 on the brain. The aim of this study was to define the cognitive and personality patterns in adult DM1 patients, and to analyse the relationship between these clinical patterns and their association with the underlying molecular defect.


METHODS
We examined 121 adult DM1 patients with confirmed molecular CTG repeat expansion and 54 control subjects using comprehensive neuropsychological tests and personality assessments with the Millon Clinical Multiaxial Inventory (MCMI)-II. We used a multiple linear regression model to assess the effect of each variable on cognition and personality adjusted to the remainders.


RESULTS
Patients performed significantly worse than controls in tests measuring executive function (principally cognitive inflexibility) and visuoconstructive ability. In the personality profile, some paranoid and aggressive traits were predominant. Furthermore, there was a significant negative correlation between the CTG expansion size and many of the neuropsychological and personality measures. The molecular defect also correlated with patients' daytime somnolence.


CONCLUSIONS
Besides muscular symptomatology, there is significant CTG-dependent involvement of the CNS in adult DM1 patients. Our data indicate that the cognitive impairment predominantly affects the fronto-parietal lobe.
Sistiaga
A
A
Experimental Unit, Hospital Donostia, San Sebastian, Spain. andone.sistiagaberrondo@osakidetza.net
Urreta
I
I
Jodar
M
M
Cobo
A M
AM
Emparanza
J
J
Otaegui
D
D
Poza
J J
JJ
Merino
J J
JJ
Imaz
H
H
Martí-Massó
J F
JF
López de Munain
A
A
D000293:Adolescent; D000328:Adult; D000368:Aged; D000704:Analysis of Variance; D015139:Blotting, Southern / Q000379:methods; D003072:Cognition Disorders / Q000175:diagnosis / Q000453:epidemiology* / Q000523:psychology*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009223:Myotonic Dystrophy / Q000453:epidemiology* / Q000235:genetics / Q000523:psychology*; D065636:Myotonin-Protein Kinase; D009483:Neuropsychological Tests / Q000706:statistics & numerical data; D010551:Personality; D010555:Personality Inventory / Q000706:statistics & numerical data; D016133:Polymerase Chain Reaction / Q000379:methods; D017346:Protein Serine-Threonine Kinases / Q000235:genetics; D011569:Psychiatric Status Rating Scales / Q000706:statistics & numerical data; D012091:Repetitive Sequences, Nucleic Acid; D013030:Spain / Q000453:epidemiology; D019680:Trinucleotide Repeat Expansion / Q000235:genetics*; D055815:Young Adult
C585517:DMPK protein, human; D065636:Myotonin-Protein Kinase; D017346:Protein Serine-Threonine Kinases