Thanks for the extra detail, Jacquie. It really makes a difference.
she lies about things she did or didn't do. For instance, she either lies or refuses to answer when questioned about her behavior
These are the sort of lies I suspected - they're very simple, "I didn't do it" kind of lies which are well within the capability of autistic kids. ALL kids lie like this at times.
Kids lie generally out of fear of punishment. Its normal. What is NOT normal, is te quantity. But in tis case from what you describe - I think the quantity is due to a combination of things but notably, the impulse control issues. She either doesn't think, or doesn't think fast enough, before acting on impulse. Then she looks at what she's done and thinks, "uh-oh," or it's when you discover the problem and ask, "What happened here?" that she thinks, "uh-oh," and tries to cover with a simple lie. It would be interesting to know - what is the most complex lie she is capable of?
A child with bipolar is capable of complex lies. A complex lie is, "I was walking the dog on the leash like you told me I must because dogs are not allowed off leash in the park, when a group of big kids came up to me, grabbed the dog and took the leash off him. Then they let him go and threw balls for him and made him chase a little kid who fell over and now the little kid's mummy is cross, but it wasn't me, it was those big kids. No, I don't know who they are, I've never seen them before, but it was them who let Snoopy off the leash, Mummy, it wasn't me. Honest."
From your description, she was born with some problems that may have nothing to do with your sister's drug/alcohol habits. Sometimes these things just happen. It could be the way the baby lay in the womb, it could have been a problem with the use of forceps in the wrong place during delivery, it could have been any one of a number of things. It's valuable information, though.
Is it a possible cause (partly or fully)? I don't know. Maybe you will never know. It could be.
The thing is, this is what you're dealing with NOW. You need a helpful working hypothesis. And maybe a good working hypothesis could be, she has impulse control issues. She then has heightened anxiety which pushes her to try to cover up what she has done for fear of punishment/your disapproval. She keeps doing the wrong thing, so she isn't learning from these experiences (which means whatever punishment you're using, even if it is just your disapproval, is not working). She has some mild physical issues (poor muscle tone especially on one side) which could have a bearing on the observed learning problems.
A couple of thoughts - you say she has a normal IQ but did well on her last report card.
Take that "normal IQ" with a grain of salt. It is unlikely to be higher than it should be; you can't fudge a higher score than you should have. But it is VERY easy, especially for a kid who is "different" in any way, to get an artificially low score. The real measure is how she is actually able to do in her schoolwork. Not just in tests, but how well does she grasp the work and how well could she do it if she really focussed on it.
However, if she can do well at schoolwork, that doesn't mean she can necessarily cope with some level of abstract information. For example, we often use sarcasm with our children. With "normal" children, this is not generally a problem. It's often used with humour, but needn't be. You might respond to the marker on the sheets with, "And I suppose that marker just leapt out of the box all by itself and scribbled on the sheets and you didn't touch them?" and you will see that little head nod out of gratitude that you fabricated a neat excuse for her, saving her the trouble!
Another thing you need to consider when you're asking her what happened - be very careful to not lead her, or prompt her to the answer you expect with your question. This was a problem I had with difficult child 3's teachers, one in particular - difficult child 3 would report being bullied, he reported one day that a particular group of boys had tripped hi up as he was running, and he fell and bloodied his knees (they were a mess when he came home from school). I had an independent witness, a classmate of difficult child 3's who stuck by him as a friend, who quietly confirmed difficult child 3's story to me. So I wrote a note to the teacher, asking him to look into it. The teacher told me what happened plus I asked difficult child 3 what the teacher said to him. It was a disaster, because the teacher desperately wanted to find there was no problem. Otherwise he would have to punish the bullies, and he was scared of their parents. So the teacher questioned difficult child 3 by saying to him, "Now tell me, you didn't really get tripped, did you? Those boys said they were nowhere near you. You must have fallen over your own feet while you were running. That is what happened, isn't it?"
In that case, it was more than merely a leading question, it was actually pressure on the kid to say that things happened otherwise. difficult child 3, eager to please, accepted the teacher's version of events and said yes, it must have happened tat way. But he was confused. difficult child 3 said to me that afternoon, "Mr S said that I must have been mistaken about what happened because my autism means I don't always see things the way other people do. I don't get it - I was so certain I saw Jimmy's foot stick out in front of me and all his friends were laughing. But Mr S said they were on the other side of the playground at the time."
difficult child 3 was not mistaken - one thing with autism, they generally don't invent things. That's why they're very bad at lying. Being bad at lying doesn't mean they don't try to lie, but they generally always get caught out, because they're so bad at it. Over time they learn to not lie, especially when they eventually learn that telling the truth is better long-term for their anxiety.
Now, my next question for you has nothing to do with possible diagnosis, but more to do with how she functions. I have one child with this problem, another without it, both with autism.
Can she multi-task? A good test for tis is, can she follow a multi-step instruction?
Example - difficult child 1 at a stranger's house, we had gone there for a casual dinner. difficult child 1 asked to use the toilet. He was about 6 years old. The man of the house said to him, "You go down the hall, turn left and it's the third door on the right."
difficult child 1 got down the hall and came back. "I got down the hall but I forgot the bit that comes next."
We took him by the hand and showed him. He had no difficulty remembering where to find it next time, because he had been there and remembered the way. But remembering the multi-step verbal instruction was his problem. He still has trouble with this but has developed a lot of strategies to cope.
Regardless of the diagnosis, "Explosive Child" should help you. You read it, take form it what you can and leave the rest. But revisit the book later because what you can use will change. There is also some good discussion on how to adapt the book to a younger child. Go to the Early Childhood forum and look at the stickies there, for more info on that book. It could be a lifesaver for you.
You mentioned odd behaviour - can you give some examples? Also, are you alone in trying to manage her, or is there someone else in her life who can help you? Some of us have husbands or partners, some of us have parents or other family members who live with us. And some of us are managing alone, which is a struggle with kids like this. But together we can support one another and this can sometimes remove that last straw from the camel's back.
I'm glad you found us, but sorry you need to. I was concentrating hard on your problems so I didn't say it before - welcome aboard.
Marg