Hippocampal atrophy predicts conversion to dementia after STN-DBS in Parkinson's disease.
BACKGROUND
Hippocampal atrophy (HA) is a known predictor of dementia in Alzheimer's disease. HA has been found in advanced Parkinson's disease (PD), but no predicting value has been demonstrated yet. The identification of such a predictor in candidates for subthalamic deep brain stimulation (STN-DBS) would be of value. Our objective was to compare preoperative hippocampal volumes (HV) between PD patients who subsequently converted to dementia (PDD) after STN-DBS and those who did not (PDnD).


METHODS
From a cohort of 70 consecutive STN-DBS treated PD patients, 14 converted to dementia over 25.6+/-20.2 months (PDD). They were compared to 14 matched controls (PDnD) who did not convert to dementia after 43.9+/-11.7 months. On the preoperative 3D MPRAGE MRI images, HV and total brain volumes (TBV) were measured by a blinded investigator using manual and automatic segmentation respectively.


RESULTS
PDD had smaller preoperative HV than PDnD (1.95+/-0.29 ml; 2.28+/-0.33 ml; p<0.01). This difference reinforced after normalization for TBV (3.28+/-0.48, 3.93+/-0.60; p<0.01). Every 0.1 ml decrease of HV increased the likelihood to develop dementia by 24.6%. A large overlap was found between PD and PDnD HVs, precluding the identification of a cut-off score.


CONCLUSIONS
As in Alzheimer's disease, HA may be a predictor of the conversion to dementia in PD. This preoperative predictor suggests that the development of dementia after STN-DBS is related to the disease progression, rather then the procedure. Further studies are needed to define a cut-off score for HA, in order to affine its predictive value for an individual patient.
Service de Neurologie Lausanne, CHUV, Lausanne, Switzerland.
Selma
S
Aybek
Francois
F
Lazeyras
Aline
A
Gronchi-Perrin
Pierre R
PR
Burkhard
Jean-Guy
JG
Villemure
Francois J G
FJ
Vingerhoets
D000368:Aged; D001284:Atrophy / Q000150:complications / Q000209:etiology / Q000473:pathology; D016022:Case-Control Studies; D015331:Cohort Studies; D046690:Deep Brain Stimulation / Q000009:adverse effects*; D003704:Dementia / Q000209:etiology*; D005260:Female; D006624:Hippocampus / Q000473:pathology*; D006801:Humans; D021621:Imaging, Three-Dimensional / Q000379:methods; D016015:Logistic Models; D008279:Magnetic Resonance Imaging / Q000379:methods; D008297:Male; D008609:Mental Status Schedule; D008875:Middle Aged; D010300:Parkinson Disease / Q000628:therapy; D011237:Predictive Value of Tests; D012720:Severity of Illness Index