been wondering about that bruise since i first saw abdulmutallab's pic. if i hadn't seen zawahiri pix before, i might've ignored it. possibility of brain damage occurred to me, of course. i mean, if you're so fervid you bang your forehead on the ground 5 times a day for a few years the results can't be all good.

from wiki:

A zebibah (Arabic "raisin") is a darkened area of callused skin on the forehead. Muslims sometimes acquire one from pressing the head to the ground during daily prayers. Because they come from this act of religious observance, they can be seen as a mark of piety.

A zebibah can be a type of acanthosis nigricans which is a sign of insulin resistance usually from type 2 diabetes. In Egypt, where zebibahs are common, the rate of diabetes was 10.2% in 2000. However, it was much larger for certain groups. For instance, the rate of diabetes was 21.9% for women aged between 45-64 years old. In addition, it was estimated that up to 56% of men and 64% of women are obese. Many of these obese people can be pre-diabetic.

and this:

The prefrontal cortex (PFC) is the anterior part of the frontal lobes of the brain, lying in front of the motor and premotor areas.

This brain region has been implicated in planning complex cognitive behaviors, personality expression, decision making and moderating correct social behavior. The basic activity of this brain region is considered to be orchestration of thoughts and actions in accordance with internal goals.

The most typical psychological term for functions carried out by the prefrontal cortex area is executive function. Executive function relates to abilities to differentiate among conflicting thoughts, determine good and bad, better and best, same and different, future consequences of current activities, working toward a defined goal, prediction of outcomes, expectation based on actions, and social "control" (the ability to suppress urges that, if not suppressed, could lead to socially-unacceptable outcomes).

Many authors have indicated an integral link between a person's personality and the functions of the prefrontal cortex.