Eyeblink conditioning anomalies in bipolar disorder suggest cerebellar dysfunction.
OBJECTIVE
Accumulating research implicates the cerebellum in non-motor psychological processes and psychiatric diseases, including bipolar disorder (BD). Despite recent evidence that cerebellar lesions have been documented to trigger bipolar-like symptoms, few studies have directly examined the functional integrity of the cerebellum in those afflicted with BD.


METHODS
Using a single-cue delay eyeblink conditioning procedure, the functional integrity of the cerebellum was examined in 28 individuals with BD (9 manic, 8 mixed, and 11 euthymic) and 28 age-matched healthy controls.


RESULTS
Analysis of the bipolar group as a whole indicated a conditioned response acquisition and timing deficit compared to controls. However, when the bipolar group was categorized according to mood state (mixed, manic, euthymic), individuals tested during mixed episodes were strikingly impaired, performing significantly worse than all other groups on both the acquisition and timing of conditioned responses.


CONCLUSIONS
These findings extend prior research implicating cerebellar functional abnormalities in BD and suggest that cerebellar dysfunction may be associated with mood state and course of illness.
Bolbecker
Amanda R
AR
Department of Psychological and Brain Sciences, Indiana University, Bloomington, IN, USA.
Mehta
Crystal
C
Johannesen
Jason K
JK
Edwards
Chad R
CR
O'Donnell
Brian F
BF
Shekhar
Anantha
A
Nurnberger
John I
JI
Steinmetz
Joseph E
JE
Hetrick
William P
WP
D000161:Acoustic Stimulation; D000328:Adult; D000704:Analysis of Variance; D001714:Bipolar Disorder / Q000150:complications* / Q000188:drug therapy / Q000473:pathology; D001767:Blinking / Q000187:drug effects; D002526:Cerebellar Diseases / Q000175:diagnosis* / Q000209:etiology*; D003215:Conditioning, Eyelid / Q000187:drug effects / Q000502:physiology*; D003463:Cues; D003984:Dibenzazepines / Q000627:therapeutic use; D004311:Double-Blind Method; D004576:Electromyography / Q000379:methods; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D011930:Reaction Time / Q000502:physiology
D003984:Dibenzazepines; C428744:10,11-dihydro-10-hydroxy-5H-dibenz(b,f)azepine-5-carboxamide