WHY HE DID IT

The real reason Nick Reiner snapped

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"Nick is a shell of a human being," says an insider

ONE month after he allegedly butchered his parents to death in their $13.5 million home in Brentwood, The National ENQUIRER has learned shocking new information about Nick Reiner.

Nick — who at press time had yet to enter a plea and was being held without bail at the Twin Towers Correctional Facility in downtown Los Angeles — reportedly suffers from schizoaffective disorder and changed his medication (due to unwanted weight gain) a month before the brutal double murders. “Once that happened, he went completely off the rails,” an insider close to the case tells The ENQUIRER.

Schizoaffective disorder is a chronic mental health condition with symptoms of both schizophrenia (psychosis) and a mood disorder, such as bipolar disorder or depression.

He was arrested on Dec. 14 ...

Antipsychotics and mood stabilizers may be used to treat the disorder. It is more difficult to treat if the patient has substance abuse issues.

At the time of the slayings, it’s unclear whether Nick — who has been to rehab at least 18 times and once referred to himself as a “nutcase” — was back on drugs.

Some sources believe Nick, 32, snapped because he’d relapsed and wasn’t on the correct medication, and he slaughtered his parents in a meth-fueled rage. (The murder weapon reportedly has not been found.)

"Nick is totally detached from reality," says the insider. "He can't seem to process or comprehend what he's done."