Adult son behaviour

Can anyone help please. My son is now 28. he was a 'normal' child apart from not speaking until about 2 which I put down to a bad reaction to his last whooping cough vaccination. He was a little disruptive in secondary school and had to be statemented as he was slow at learning and needed 1to1 help in lessons. SInce leaving school he has be unable to hold down a job, always spends his wages the day he gets them on alcohol and going out leaving no money for the rest of the week. He manages to stay in the job for the longest 4 months. He has been homeless because of this and so arrested and now has criminal record. His personal hygiene is non existant, it is a fight to get him to have a bath his clothes are a mess but polishes his shoes within an inch of their life! He is also a constant liar and has thieved money and objects from his family. He is currently staying with a friend with no job etc. I'm at my wits end  with him, and wonder if he has mre underlying problems.

[Sally44]

He may well have other things going on, but as an adult your son now has to be the one asking for assessments to be made.
If you are thinking he might be on the autistic spectrum, I would google DSM IV for autism and see what the diagnostic criteria is.  Someone has to have difficulties in each category and has to have enough of them to get a diagnosis.
However you must be very concerned at the fact that he is unable to hold down a job, has become homeless and now has a criminal record.  
If you think he is on the spectrum, and as you have said he was statemented (does that mean you are in the UK?), if you are in the UK I would advise you to contact the national autistic society on www. nag.org.uk.  
I think that social services should be involved as he is a vulnerable adult.  Even without a diagnosis I would contact them and tell them your concerns.  You tend to get quicker results if you write it in a letter (and keep a copy of it), because then you have proof that you have asked for them to become involved.
It is very common for adults with all types of difficulties to have problems with money.  Again he is vulnerable is he spends all his money on the first day.  I have a sister with learning difficulties and all her bills are paid by direct debit and she is only allowed to withdraw a certain amount of money each week.  She also has carers come into her flat (she lives independently), and they help her with cleaning and shopping etc.  
Also google Executive Function Disorder to see if that sounds like your son.
But at the end of the day, if he doesn't have the skills to look after himself he will need input from social services to ensure he is houses, fed, safe etc.  They might have something like sheltered housing.
He also needs a way of structuring his free time.  Does he have any hobbies?  If so these need to be nurtured and it might again need either Social Services or an Occupational Therapist to support him in accessing social activities.  But that is far better than leaving him to be swayed by any unsavoury character who realises he can get your son to spend all his money on alcohol.  Unfortunately there are many people around who would see your son as a free meal ticket either getting him to buy alcohol or drugs.  Again, I would suggest you send that letter to social services and specifically put in the phrase that "he was statemented as a child and is now a vulnerable adult".  And I would also look at talking with your son about further assessments and about supports that are available to him.