In our last article, we reported new research findings that refute the claim by some plaintiffs’ attorneys that an officer putting a knee on the back of a prone suspect can cause fatal “restraint asphyxia.”
Now a different research team, headed by the same scientist, is challenging another allegation sometimes raised by police critics: that the electrical charge from a conducted electrical weapon (CEW) may cause or exacerbate excited delirium by raising the concentration of the brain-affecting hormone serotonin to a toxic level in a suspect’s blood.
Dr. Mark Kroll, lead author of the new study, writes that “there are some parallels between the signs” of a dangerous serotonin level and excited delirium syndrome [ExDS]. This, he says, has led to “a leap of logic by some litigators and a few isolated physicians.”
Electroconvulsive therapy [“shock treatment”] for severe mental depression is known to significantly raise serotonin levels, so it seemed “plausible” to conjecture that a discharge of a conducted electrical weapon could have a similar effect.
However, Kroll, an adjunct professor of biomedical engineering at the University of Minnesota and California Polytechnic State University, points out that a typical shock treatment delivers about 20 watts of electrical power, versus less than two watts from a CEW application. So the suggested link seemed doubtful to him.
He and his team, consisting of three physicians and an attorney, decided to analyze the impact on serotonin from a CEW discharge rather than direly hypothesize about it—using data from the first time such tests have been conducted, he says.
Strategic Blood Draws
Thirty-one cadets from a Texas police academy, ranging in age from 21 to 55 and all but three of them male, volunteered to undergo a controlled five-second exposure from a standard TASER X26 CEW.
The weapon’s electrical power was delivered through alligator clips to the subjects’ clothing at the shoulder and waist —a “full-trunk exposure”—“to obtain the highest level of muscular contraction” for the upper and lower extremities. This “very broad electrode spread,” Kroll explains, offered the best chance of “detecting an increase in serotonin.”
Blood samples were drawn before and immediately after the exposure, as well as 24 hours later.
And the Results…
Thorough analysis of the samples revealed that serotonin levels increased “trivially” after the CEW application but in all cases “remained within the clinically normal range,” Kroll writes. Indeed, the negligible increase in serotonin concentration from CEW exposure “is far less” than the increase seen from “acute physical exercise” in other studies.
With this finding, the researchers conclude that “the speculated link between a CEW and excited delirium is lacking in support.”
Kroll reminds Force Science News readers that the American College of Emergency Medicine guidelines on excited delirium recommend that officers “use electrical weapons to restrain ExDS subjects to shorten the length of struggle [with police] and improve [the subjects’] survival.”
He acknowledges that serotonin toxicity and the deranged condition of excited delirium do share some clinical characteristics, including altered mental state and agitation. But individuals with a serotonin overload “do not share the aggressive violent behavior displayed by [subjects] with ExDS.”
The published report of this study, “Electrical weapons and excited delirium: shocks, stress, and serum serotonin,” appears in the journal Forensic Science, Medicine, and Pathology. A free abstract, plus a link for accessing a paid copy of the full study, is available below.
Dr. Kroll, a member of the scientific advisory board for the TASER manufacturer.