Effects of intravenous ketamine on explicit and implicit measures of suicidality in treatment-resistant depression.
BACKGROUND
Intravenous ketamine has shown rapid antidepressant effects in early trials, making it a potentially attractive candidate for depressed patients at imminent risk of suicide. The Implicit Association Test (IAT), a performance-based measure of association between concepts, may have utility in suicide assessment.


METHODS
Twenty-six patients with treatment-resistant depression were assessed using the suicidality item of the Montgomery-Asberg Depression Rating Scale (MADRS-SI) 2 hours before and 24 hours following a single subanesthetic dose of intravenous ketamine. Ten patients also completed IATs assessing implicit suicidal associations at comparable time points. In a second study, nine patients received thrice-weekly ketamine infusions over a 12-day period.


RESULTS
Twenty-four hours after a single infusion, MADRS-SI scores were reduced on average by 2.08 points on a 0 to 6 scale (p < .001; d = 1.37), and 81% of patients received a rating of 0 or 1 postinfusion. Implicit suicidal associations were also reduced following ketamine (p = .003; d = 1.36), with reductions correlated across implicit and explicit measures. MADRS-SI reductions were sustained for 12 days by repeated-dose ketamine (p < .001; d = 2.42).


CONCLUSIONS
These preliminary findings support the premise that ketamine has rapid beneficial effects on suicidal cognition and warrants further study.
Price
Rebecca B
RB
Department of Psychiatry, Mount Sinai School of Medicine, New York, New York, USA. rprice@eden.rutgers.edu
Nock
Matthew K
MK
Charney
Dennis S
DS
Mathew
Sanjay J
SJ
D015331:Cohort Studies; D003863:Depression / Q000188:drug therapy / Q000523:psychology*; D004351:Drug Resistance; D018691:Excitatory Amino Acid Antagonists / Q000008:administration & dosage / Q000494:pharmacology*; D005260:Female; D006801:Humans; D007262:Infusions, Intravenous; D007649:Ketamine / Q000008:administration & dosage / Q000494:pharmacology*; D008297:Male; D008875:Middle Aged; D011569:Psychiatric Status Rating Scales; D013405:Suicide / Q000523:psychology; D000092864:Suicide Prevention
D018691:Excitatory Amino Acid Antagonists; D007649:Ketamine