Royce White's NBA career is off to a rocky start. (Getty Images)

Royce White's struggle with anxiety issues has been well-documented. He was red-flagged before the draft as teams steered away from him.

The Rockets ended up taking a chance, picking White 16th overall.

But White is missing from the opening day of training camp for what the team is officially calling "personal reasons." According to Fox 26 Sports in Houston, White's absence is related to his anxiety issues:

[White] told FOX 26 Sports the personal matters are related to the fact that he suffers from anxiety issues.

"We are trying to figure out a plan for me to be healthy and successful long-term," White said. "It's not really anything that's going on right now. It's more of trying to take a proactive approach and trying to put together a solid plan.

"It is definitely linked with my anxiety, sure, but it's not so much as far as my anxiety now. Basically what happened was my doctor, we discussed it, and it was decided the way the plan was now just wasn't logistically healthy.

"So what can we do strategically to try and improve the chances of everybody being successful in this situation, my success and the Rockets success? If I fail then that's not good for them, either, because it's an investment."

White said he did not know how long it would take before he rejoined the team.

Kevin McHale told reporters he has "no idea" how long White will be out.

Later Tuesday night, the Rockets issued the following brief statement on behalf of GM Daryl Morey: "We are committed to Royce's long-term success and we will continue to support him now and going forward."

White said this before the draft: "Panic attacks are like, if you have one you are susceptible to another one. Your mind races and the adrenaline starts to pump. The adrenaline is so powerful it makes your heart beat faster. That sends it back to your mind, and you're like, my heart is beating. Panic on top of panic on top of panic. It feels like you're dying."

Following his selection, White admitted, "Of course I'm worried about how much I have to fly in the NBA. I'm very worried about the schedule. I just don't like to fly. I'm very scared. Bottom line."

So it's clear that this transition into the NBA life isn't going to be a piece of cake for him. An NBA rookie is walking into a whole new world with brand new stresses and pressures that he's never felt before. It would be challenging for anyone, much less someone who suffers from anxiety issues.

Obviously, it's a shame to see White's issue affecting him so early in his career but he's overcome in the past and this is just another small bump in the road for him.