Inducing long term low latent inhibition From what I have gathered of low latent inhibition, it is an extreme increased level of dopamine in the brain.. dopamine is a neurotransmitter and hormone. 

Increasing it has many advantages and a few nasty disadvantages.

While improving concentration, mood, energy, and libido for starters,
too much can cause side effects such as addiction and a host of mental disorders. (schizophrenia and bipolar to name two)

I'm looking for those who might have more knowledge of the subject than I do: there is a lot of controversy over the internet and half of it can't be believed.
So, for the question part:

1. Is increased dopamine levels the source (or at least main source) of LLI?

2.Is Dopamine increased more through direct supplements such as DHA which supposedly affect Dopamine levels directly, or supplements such as L-Dopa which claim to affect the precursors?

I've done my own research and am still looking for answers to the benefits, risks, and induction of such to lower latentcy... just looking for others' knowledge and/or experiences.
Low latent inhibition is not an ideal state...Wikipedia lists several potential problems including attentional and emotional dysregulation, psychosis, and negative emotionality. Wikipedia also suggests that intelligence may moderate effects on well-being, such that more highly intelligent people could cope with stronger stimulation more effectively, and possibly enhance creativity (Carson, Peterson, &amp; Higgins, 2003).

As for dopamine, there's a lot to read and thoroughly reconsider before going ahead with any attempt to alter it. The dopamine hypothesis of schizophrenia is one particularly noteworthy concern with heightened dopamine levels; nausea is another risk, and addiction to the means of alteration is another. I don't know that this last risk is any less serious with legal drugs, or even naturally rewarding behaviors.

That being said, some regulated drugs are prescribed for disorders of low dopaminergic activity, including Parkinson's and (to some extent) attention-deficit hyperactivity disorder, including $_\mathbf L$-DOPA and methylphenidate. I link here to the overdose sections to emphasize that using them is not a good idea without a strong recommendation from a doctor in support and supervision of medicinal use. Even those with severe disorders who basically need these medications may suffer complications, so the likelihood of normally functioning individuals benefitting safely from (ab)use of these drugs is rather low at best.

BTW, @ChuckSherrington's comment is wisely made, and I want to emphasize also that I'm only mentioning these drugs because they exist and are sometimes prescribed for disorders that sometimes result from harmfully low dopamine levels. These medications should NOT be used by normally functioning individuals. They have several undesirable side effects, and could be particularly dangerous if used to deliberately elevate dopamine receptor activity above normal. Beside that, many if not most are regulated substances, and illegal to use without a prescription.

This is not a place to look for people who have experimented with dopaminergic drugs on normally functioning individuals: such experimentation is dangerous and unethical, especially if conducted in an uncontrolled manner without professional medical support on hand. Personal use of a drug like $_\rm L$-DOPA or methylphenidate without a prescription is not experimentation in a scientific sense, but is abuse in a legal sense. 

Some properly ethical and cautious research has investigated the effects of various dopaminergic drugs on normal populations, and results seem mixed at best, and quite scary at worst. As a near-worst case, consider cocaine: it acts on much more than dopamine, and tends to dysregulate it, not just temporarily block its reuptake. These aspects make it a very messy way of manipulating dopamine, and leads to some of its well-known dangers. This may be an extreme example, but one shouldn't assume so; any psychoactive drug has some potential to upset homeostasis in a lasting way and in more ways than one intends.

Methylphenidate might be a near-best case pharmacodynamically, but it too affects more than just dopamine, and has its share of dangers, as I mentioned above. What makes it noteworthy is the debate surrounding it as a potential nootropic vs. drug of abuse. Here's an interesting excerpt from Wikipedia:


  Methylphenidate is sometimes used by students to enhance their mental abilities, improving their concentration and helping them to study. Professor John Harris, an expert in bioethics, has said that it would be unethical to stop healthy people taking the drug. He also argues that it would be "not rational" and against human enhancement to not use the drug to improve people's cognitive abilities.[97] Professor Anjan Chatterjee however has warned that there is a high potential for abuse and may cause serious adverse effects on the heart, meaning that only people with an illness should take the drug. In the British Medical Journal he wrote that it was premature to endorse the use of Ritalin in this way as the effects of the drug on healthy people have not been studied.[98][99] Professor Barbara Sahakian has argued that the use of Ritalin in this way may give students an unfair advantage in examinations and that as a result universities may want to discuss making students give urine samples to be tested for the drug.[100][Emphasis added.]


Evidently there are cases to be made for both perspectives on methylphenidate, and a variety of ramifications to consider. More research would be helpful, especially for the sake of isolating important mechanisms of action and reducing undesirable side effects. Until that much is done successfully, methylphenidate seems too controversial to recommend at best, and downright dangerous to recommend at worst. Furthermore, being a Schedule II drug in USA, it is illegal to possess or distribute without prescription.

Another notable prospect of sorts (though still Schedule II) is buproprion. From Wikipedia:


  The primary pharmacological action of the drug is as a mild dopamine reuptake inhibitor and also a much weaker norepinephrine reuptake inhibitor as well as a nicotinic acetylcholine receptor antagonist...
  
  According to the US government classification of psychiatric medications, bupropion is "non-abusable".[93] In animal studies, squirrel monkeys and rats could be induced to self-administer bupropion, which is often taken as a sign of addiction potential; however, there are significant interspecies differences in bupropion metabolism.[54] There have been a number of anecdotal and case-study reports of bupropion abuse, but the bulk of evidence indicates that the subjective effects of bupropion are markedly different from those of addictive stimulants such as cocaine or amphetamine.[94] However bupropion is reported to be abused in Canada.[95]


One look at Tryon and Logan (2013) is more than enough to tell that the US government is wrong yet again on drug abuse; this one can definitely be abused in a really unsettling way (seriously, view at your own risk; it's got some gruesome imagery). However, to be fair, I can't verify that the cited source for the US government [93] says "non-abusable"; the link only leads to a table where bupropion is listed under Low Abuse Potential...but this seems pretty outdated in light of the news from Canada, unfortunately. Granted, this is primarily a problem with intravenous administration, which is not intended...but clearly the potential exists, and is bad enough to outweigh any merits of deregulation I could imagine. Again, further demonstration of how hazardous this psychopharmacological minefield of dopaminergic drugs really is...The only safe advice is to steer clear – barring any exigent need and prescription for personal medical use, of course – but that doesn't apply here.

References
- Carson, S. H., Peterson, J. B., &amp; Higgins, D. M. (2003). Decreased latent inhibition is associated with increased creative achievement in high-functioning individuals. Journal of Personality and Social Psychology, 85(3), 499–506. Retrieved from ResearchGate.

54. Dwoskin, L. P., Rauhut, A. S., King‐Pospisil, K. A., &amp; Bardo, M. T. (2006). Review of the pharmacology and clinical profile of bupropion, an antidepressant and tobacco use cessation agent. CNS Drug Reviews, 12(3–4), 178–207.
93. Center for Substance Abuse Treatment. (2000). Abuse potential of common psychiatric medications. In Substance abuse treatment for persons with HIV/AIDS (Treatment Improvement Protocol (TIP) Series, No. 37, pp. 83–84). Rockville, USA: Substance Abuse and Mental Health Services Administration. Retrieved from http://www.ncbi.nlm.nih.gov/books/NBK64916/table/A67504/.
94. Lile, J. A., &amp; Nader, M. A. (2003). The abuse liability and therapeutic potential of drugs evaluated for cocaine addiction as predicted by animal models. Current Neuropharmacology, 1(1), 21–46.
95. Tryon, J., &amp; Logan, N. (2013, September 18). Antidepressant Wellbutrin becomes ‘poor man’s cocaine’ on Toronto streets. Global News: Health. Retrieved from http://globalnews.ca/news/846576/antidepressant-wellbutrin-becomes-poor-mans-cocaine-on-toronto-streets/.
97. Harris, J. (2009). Is it acceptable for people to take methylphenidate to enhance performance? Yes. British Medical Journal, 28(8), b1955. Retrieved from http://livingtomorrow.livejournal.com/59100.html.
98. Chatterjee, A. (2009). Is it acceptable for people to take methylphenidate to enhance performance? No. British Medical Journal, 338, b1956. Retrieved from http://repository.upenn.edu/cgi/viewcontent.cgi?article=1079&amp;context=neuroethics_pubs&amp;sei-redir=1.
99. BBC News. (2009, June 19). Ritalin backed as brain-booster. Retrieved from http://news.bbc.co.uk/2/hi/health/8106957.stm.
100. Davies, C. (2010, February 21). Universities told to consider dope tests as student use of 'smart drugs' soars. The Observer: Education: Student Health. Retrieved from http://www.theguardian.com/society/2010/feb/21/smart-drugs-students-universities.