Black out may mean different things to different health professionals. I wonder if his black outs mean that "he behaves unlike his real self" that is why he received a diagnosis of Cyclic Depression?
Anyway,symptoms of major depression include disturbance of sleep and appetite, diminished interest in previously enjoyable activities, suicidal thoughts, diminished concentration, feelings of hopelessness/helplessness/worthlessness, and fatigue. The exact cause of depression is unknown. It may be due to deficiency of abrain chemical called serotonin or other so-called neurotransmitters", genetic factors, medical conditions, or stressful events.
Depression may be considered RECURRENT (or cyclic?)if there are separate episodes of depression of at least 2 months interval.
Depression may also have psychotic features if this icludes hallucinations or delusions (false beliefs)
Depression may also have catatonic features if symptoms include bizarre posturing, or echolalia (repeating the words by the person speaking to him).
I suffer blackouts as a result of; several congenital developmental abnormalities, A series of concussions from pre-school to my early 20's. The later concussions were from being a downhill ski racer. I had 4 during 15-17. The most dangerous ones were only two weeks apart.
Basically birth defects. I had migration anomalies (Cells develop, but migrate to the wrong part of the brain), Focal Lipomas (Fatty benign tumors), Hemispheres not symmetrical, pressure on the optic nerve causing "Short circuits", inner ear not developed normally causing reduced hearing in my left ear and constant ringing. Vascular difficulties etc.
(These types of anomalies often cause retardation and are more frequent in twins. Many times symptoms do not start to manifest themselves until their 30's - 40's. It isn't rare, nor common. I had it explained to me that the body, particularly the brain can compensate. Our bodies peak at around 25. We can compensate, but after a decade, more or less, you systems begin to lose the fight.)
Post Concussion Syndrome
Difficult to diagnose, but two surgeons and three neurologists feel that the head bangs effects are multiplied by the brain defects. It appears that surgeries may get relief for some symptoms.
Significant short term memory problems, loss of balance (I usually walk with a cane, blackouts, and severe attacks of excruciating pain. I now suffer from depression and am being treated for that. Reluctantly, I have gone on disability, it felt like a "Loss". In retrospect, that was a dumb decision based on ego. If he begins to go that way. As I had it explained to me "you have paid into it, that is why it is there."
I have learned to be very specific describing "Blackouts". Does he lose consciousness, or does he lose blocks of time. Time that he cannot remember at all, but he did function during them. Driving to work, having conversations, maybe a little out of it? My blackouts are ones where I lose time, sometimes an entire day, usually, just hours.
MRI's lead to the discovery of the anomalies. My blackouts were originally thought to be seizure related. Absence seizures do cause the blackouts I described; functioning, but having no recollection. There are a number of anti-seizure medications that will completely handle the seizures. But it is not a cure.
Other possibilities are TIA Transient Ischemic Attack. Basically mini strokes. I was never treated for this.
AVM Arterio Veinous Malformations. A "birdsnest" of small veins within the brain. They can cause all sorts of issues, including the ones you describe. Surgery is the option here. There is a process called the "Gamma Knife". It is non-invasive surgery that uses focused gamma radiation as a knife. Stereo tactic is another non-invasive surgery. There is also typical surgery. These can also cause leaking aneurysms. ScrippsClinic in Lahoya, CA and UCLA Medical are one of the leaders in this type of cutting edge surgery (OOP