Biology & Treatments for Compulsive Eating & Behaviors | Dr. Casey Halpern

KEYPOINTS

• 01

  Deep brain stimulation delivers medication as electricity

  Halpern, a neurosurgeon, describes DBS as implanting a thin insulated wire whose tip contacts deliver current from a pacemaker-like pulse generator to a tiny brain region. The most consistent effect is immediate relief of tremor, even after 20 years of shaking. Side effects within a few millimeters, such as brief laughter or panic, revealed therapeutic uses: Parkinson's patients sometimes report that gambling, compulsions or low mood improve along with tremor.

• 02

  OCD involves dysregulated, not simply overactive, cortical circuits

  The orbitofrontal and prefrontal cortex, which support inhibitory control, function abnormally in OCD, along with their projections to the dorsal striatum (caudate and putamen) and the ventral striatum, including the nucleus accumbens. Halpern cautions against thinking of 'up or down' activity; the aim is to normalize function.

• 03

  DBS for OCD helps only some patients so far

  Surgical risk for OCD is similar to that for tremor, but the payoff is less reliable. About 50% of patients respond, and responders still have symptoms, so many psychiatrists hesitate to refer. Halpern performs DBS for OCD in only three to five patients a year and is leading research to target obsessions more specifically. He sees obsessive traits on a spectrum, some of which help in surgery or business.

• 04

  The nucleus accumbens gates reward-seeking, and strong rewards can hijack it

  When the ventral striatum is perturbed, rats pursue rewards despite foot shocks. In mice, two weeks of 60% fat food leaves the nucleus accumbens functioning abnormally, partly hyperactive and partly hypoactive, likely predisposing continued overeating and eventually habit. Halpern views loss of control as a common thread across binge eating, addiction and OCD, though it is not a formal diagnosis.

• 05

  Not all obesity is a binge-eating problem

  Obesity is a phenotype with many causes. Halpern credits mentor Tom Wadden with warning that only about 20% of people with obesity show addiction-like eating, still an enormous number. Binge eating disorder affects an estimated 3 to 5% of people and is likely underdiagnosed in obesity.

• 06

  A binge has a strict definition; loss-of-control eating is far more frequent

  A binge requires loss of control plus eating an unusually large amount in a short time, perhaps half a day's calories compared with normal meals. Severe cases binge about once a day; moderate cases three to four times a week. Loss-of-control eating can occur dozens of times a week, with some trial patients reporting 20 to 30 episodes.

• 07

  A two-hit model for how binge eating develops

  Halpern's hypothesis, which he says is unpublished: the first hit is a predisposition everyone shares to some degree, magnified by cheap, refined, hyperpalatable food we did not evolve with, such as high-fructose corn syrup even in bread. The second hit is a stressor, probably recurring. Shame adds a third layer. Both anxiety and disinhibition, as with alcohol, can trigger binges, suggesting imbalance in either direction.

• 08

  Episodic stimulation beats continuous stimulation for episodic disorders

  Depression or Parkinson's may behave like 'state' disorders needing continuous therapy. Binge eating, addiction and OCD involve intermittent episodes in otherwise normal days. In mice, Halpern's group, publishing in PNAS, found a nucleus accumbens signal that predicts loss of control; triggering 5 to 10 seconds of stimulation only then blocked binges durably, while continuous stimulation lost its effect, likely through tolerance. Over time the predictive signal itself became less frequent.

• 09

  Anorexia and compulsive overeating may be more alike than different

  Both can reflect compulsions to over- or under-eat despite risk, shaped by social pressures and similar brain vulnerabilities. Anorexia has the highest mortality of any psychiatric condition, from suicide and metabolic complications. Because implanting devices in very underweight patients risks wound erosion, non-invasive approaches are needed, but targets must first be found inside the brain.