L A Trittle has suggested in his paper ‘Alexander and the Killing of Cleitus the Black’ that the Great Macedonian was suffering from PTSD when he murdered Cleitus at Maracanda.
Trittle accepts that, ‘The assertion that Alexander, or anyone in the ancient Greek world, could have been troubled by such a “modern” phenomenon will unsettle some for sure.’ He proceeds to demonstrate that there are clear examples of hysterical blindness in the sources so we may consider the point that ancient warriors were subject to similar stresses as their modern counterparts. This is a long way from showing that Alexander was suffering from PTSD, however.
Trittle supplies a list of the symptoms of the condition, viz.;
‘1) Loss of authority over mental functions – particularly memory and trustworthy perception.
2) Persistent mobilization of the body and mind for lethal action, with the potential for explosive violence.
3) Persistence and activation of combat survival skills in civilian life.
4) Chronic health problems stemming from the chronic mobilization of the body for combat.
5) Persistent expectation of betrayal and exploitation; destruction of the capacity for social trust.
6) Persistent preoccupation with both the enemy and the veterans own military/government authorities.
7) Alcohol and drug abuse.

He then singles out the following as typical of Alexander - 1 (but only trustworthy perception) 2, 5 (but only social trust) and finally 7, although later he attempts to show a predisposition for suicide.
These symptoms are not given equal weight by the British Institute of Psychiatry with the alcohol abuse being relegated to a secondary indication.
There are many problems with diagnosing Alexander with PTSD in 328/7 the main one being that of Trittle’s point 4. It was five years before Alexander died and he showed no sign of the chronic health problems con-commitant with the condition. Conversely he displays a rude good health sufficient to recover from his chest wound and make it across the Gedrosian desert!
The BIP stress the effects on the memory, but Alexander is allegedly able to quote freely from Euripides and Homer, during his final illness he can recognise many of his men not feats of a troubled memory.
Again Alexander continues to administer the Empire and run the campaign, he intervenes in the various quarrels of Hephaistion and demonstrates a political tact not associated with PTSD.
All this suggests conclusively that Alexander was not suffering from PTSD. His drinking is merely part of Macedonian culture as it is part of the rugby ethos. That fights will occur when alcohol and testosterone are thrown into a cocktail with insult and antagonism does not require a psychological illness; unless every city centre is full of teenagers similarly suffering every Friday.
We might even posit what allowed the ancient warrior to seemingly remain free of the crippling psychological consequences of combat.
First and foremost, even in Alexander’s time there was not the total separation of the military and civilian. In the fourth century BC most citizens will have experienced war and combat this meant that the returning soldiers did not find themselves outside of society they were fully accepted and integrated. This was not the case with the men returning from even WWI, in fact even the heroes of ‘The Charge of the Light Brigade’ were reduced to beggary, once war became divorced from the general experience soldiers found themselves unable to relate the horrors that they had seen in battle. Again, whilst feeling someone else’s intestines spilling down your arm is unpleasant as is having a spear thrust in your genitals, there is still a feeling of self determination, your own efforts can improve your chances. On a modern battlefield mutilation speeds unseen out of the blue and that impotence in the face of death increases the stress levels exponentially. Further, the modern soldier fight in dispersed formations which lower morale, increasing stress in antiquity you would generally be able to smell your comrades let alone feel them, proximity has been shown to increase the will to combat.
Trittle does mention some of these points but only to dismiss them and he only treats the so-called ‘Reign of Terror’ ignoring the clear evidence that Alexander was functioning very well. It is also somewhat odd to question a man in the midst of a military campaign among nobles of dubious loyalty for being suspicious and on his mettle. In fact, Alexander continued to hand out independent commands which speaks of more confidence in his lieutenants than the hyper-paranoid interpretation of Alexander would allow.
So whilst the case for combat stress in the ancient world in proven it is a step too far to impute that Alexander was suffering from post-traumatic stress disorder.