Hi there,
First of all thank you for sharing your experience/opening up.
My mother suffers with Bipolar 1 and has been on and off medications almost my whole life (she has also been in and out of the psych ward year after year (except for when we moved states/changed environments).
I can relate to you when you mention the disturbing texts as I often receive this content from my mother (usually it surrounds religion/God/the bible) but it can often get really out of control (I get spammed with long winded religious based paragraphs that sometimes can include disturbing content (police in the past have actually told me it's considered harassment). However it has been an on and off thing I've dealt with for years that I find gets exacerbated in her manic episodes.
I myself (the eldest daughter) had to take on the role as "parent" at an early age due to this, taking on the responsibilities of my mother when she fell ill (having to cook, clean, look after my younger brother when we were in school). I later ended up developing substance use problems (however I would be functioning for a long period of time followed by a series of mental health episodes that mimicked my mothers). However I can say from experience if I am not abusing substances the bipolar 1 gene is not set off and I no longer experience these "manic" symptoms I grew up with in the home. Personally what would set off my episodes were stimulants and alcohol.
I can say from experience having all the right supports set up in place really helps. It can be super overwhelming and stressful (I used to have to hide what was going on at home from my friends and didn't really understand what was going on myself when I was younger.
I would definitely recommend looking up Dr Tracey Marks on YouTube as she has very helpful informative videos that explains bipolar 1 / bipolar 2 (and other mental health disorders or concerns/info you might be interested in). She goes through the symptoms and how to manage this and would even be helpful for someone who has a family member that may or may not suffer from it. I like how she explains things in a simplistic way that's easier to digest than other people I've come across or the alternative of reading the DSM-5 manual (diagnostic statistical manual). I found for both me myself (having struggled with mental health) and understanding the disorder/signs and symptoms to look out for is super helpful. Understanding the signs of an episode early is very helpful/setting up a safety/relapse prevention plan with your family members local psychologist would be good too. Anyways again, Dr Tracey Marks (YouTube) provides really great tips on how to manage bipolar/signs to look out for in others and what to expect.
From my own understanding and experience living with it at home, Bipolar 1 usually consists of manic episodes that could last for months if left untreated. There's the euphoric part of the mania that consists of decreased need for sleep, talkativeness, increased energy, grandiose plans. Then there's also the dysphoric element I've noticed is reoccurring in my own experience and from what I've read up on. So dysphoric being the opposite of euphoric, the person may get more agitated, raise their voice, develop superstitious beliefs/magical thinking. Worst case if the dysphoric type of mania continues the person also risks falling into psychosis or a psychotic like state where they may hear voices, hallucinate, feel paranoid (basically their behaviour becomes very strange and in some cases frightening.
The manic phase can often be followed by a depressive phase (however the depression/low mood levels differ depending on the person's ability to cope/what supports they have/environment etc). The depressive phase being lack of energy, lost motivation, fatigue, low mood and in some cases suicide ideation.
Overall in my experience from what I've grown up with in the home and what I've researched online Bipolar 1 is more intense than bipolar 2 in how it presents I guess you could say.
Bipolar 2 to my knowledge (correct me if I'm wrong as it's different for everyone) I believe consists of a 2 week period of mania/hypomania (hypomania being the less intense version of mania) so for some people they are still able to work and function normally during this time and it isn't prolonged like mania in bipolar 1 that can last for months. The person just may have increased energy, productivity, maybe a sense of relief as it would feel better than the periods of depression (low mood/fatigue).
Overall both include a cycle of depression and mania (however as I said the hypomanic episode in bipolar 2 usually only lasts for 2 weeks and is easier to manage/most people can continue working and functioning (they just feel more energised, productive and I suppose elevated compared to when one is in the depressive phase.
Like I said before definitely read up on this, get educated and I think once you have a better understanding of what your family member is going through it will be easier to empathise / notice the signs.
Definitely get in touch with a support line if you feel you need some counselling if you happen to be the caregiver of someone who suffers.
It can be tough ensuring someone with bipolar is regularly taking their meds (from my experience my mother would often lie/not take hers because she "felt better") but really the "I feel better" could be the beginning of a manic episode/cycle.
Get in touch with your local community centre (free psychology/psychiatrist/social worker) essentially having a team out in the community can really help.
Setting up alarms for the person with bipolar 1 or 2 to take their medication (this goes for any mental health disorder that requires medication. Tracking sleep (6-9 hours preferably).
Isolation for the person who suffers with this isn't very healthy and may lead to them self medicating (as you mentioned alcohol). Alcohol I found with my own issues caused decreased mood/more depression, anxiety, memory loss and brain fog (there are medications your brother can take instead of drinking that may better help him manage his anxiety/depression levels).
Definitely get him into see a doctor to get a referral to a psychologist/psychiatrist. If he does in fact have bipolar he most likely needs to be on medications (as if it is left untreated that person risks being hospitalised against their will/it will affect his ability to work, his reputation, burnt bridges etc which creates isolation which is a huge risk factor for anyones mental health (but esp when there is the element of substance abuse/that person turning to self medicate to manage the symptoms).