Brief Answer:
Read below.

Detailed Answer:
Hello again! I am sorry to see that you still remain so preoccupied with the possibility of having cognitive impairment.

The causes I have to say are pretty similar with those in older adults, only the lower the age the more exceptional they are and often in the setting of a familiar genetically inherited mutation.

So the causes include:

- neurodegenerative diseases: alzheimer, fronto-temporal dementia, lewy body dementia
- vascular dementia (but of course in the setting of stroke)
- chronic long standing alcohol abuse
- vitamin B12 deficiency
- low thyroid function
- there is also a whole host of other, mostly inherited conditions (can appear earlier, from childhood), but they impair all brain functions, have many other signs like seizures, paralysis, balance issues, damage to other organs. So dementia would be one of the least issues, much more prominent manifestations, diseases such as adrenoleukodystrophy, spinocerebellar ataxia, gangliosidosis, neuroacanthocytosis, Huntington's....the list can go on and on really, but as I said many other manifestations, doesn't make much sense continuing.

Another cause, I would say the most common in young people, would be mood disorders like depression or anxiety, which impair concentration causing difficulty in retaining information.

I remain at your disposal for further questions.

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Brief Answer:
Read below

Detailed Answer:
There are no neurodegenerative diseases which involve selectively the visual memory alone, they do involve other areas of cognition, they involve the cerebral cortex bilaterally. Stroke in theory could impair only selected regions, but it is an acute event with other signs which you would've been aware of. Also didn't you score great in Memtrax and Corsi block tapping test?

As for ADHD, by definition ADHD symptoms appear before the age of 12. Also to be honest, you ask about the cause to your problems, but I am not sure what your problems are. I did go back to past questions of yours, both involving me or other colleagues and you never seem to give much detail, but only ask about tests, you seem to have become an expert in the field :)
Tests were designed by doctors but that is to help us when we are in doubt, to create measurable criteria for our patients and studies, they are not everything and certainly not meant to bring more distress to patients as they seem to be doing in your case. Furthermore as you've already been told their results can be distorted by anxiety.
So you really should try to take a break from this issue. I honestly do not believe there is something wrong with your cognitive abilities, already listed many causes why, the more tests you undergo the more anxiety you'll instill into yourself and risk of having worse scores, will risk entering a vicious circle.

I hope things will work out for the best.

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Brief Answer:
You're welcome.

Detailed Answer:
Yes, generally both are affected and the verbal issues are more apparent.

I hope you will be able to get over this fear of dementia.

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