I has recently decided to go vegan. Do you follow any special diet?
No , vegetarianism had its origin from ancient India and ancient Greece.
There are a few versions of it. It is usually referred to abstaining from all animal products in the diet, and also big industrial farming of aniamls.
The diet was closely connected with the idea of nonviolence toward animals (called "ahimsa" in India),done as a religious practice
Donald Watson coined the tern in 1944 when he co founded the Vegan Society in England.  They defined it as the doctrine that man should live without exploiting animals.
Vegetarianism is strongly linked with a number of religions that originated in ancient India.such as buddhism, Hinduism.The killing of animals was sacred 
If you are strictly vegan, you need to take supplemental vitamins, like vitamin B12.
Nutritional neuroscience
Nutritional neuroscience is the scientific discipline that studies the effects various components of the diet such as minerals, vitamins, protein, carbohydrates, fats, dietary supplements, synthetic hormones, and food additives have on neurochemistry, neurobiology, behavior, and cognition.
Recent research on nutritional mechanisms and their effect on the brain show they are involved in almost every facet of neurological functioning including alterations in neurogenesis, neurotrophic factors, neural pathways and neuroplasticity, throughout the life cycle.
Relatively speaking, the brain consumes an immense
vegetarian diet that includes eggs and dairy.
- Vegan diet: In addition to the abstentions of a vegetarian diet, vegans do not use any product produced by animals, such as eggs, dairy products, or honey. The vegan philosophy and lifestyle is broader than just the diet and also includes abstaining from using any products tested on animals and often campaigning for animal rights.
Vegetarian diets Semi-vegetarian diets.
- Semi-vegetarianism: A predominantly vegetarian diet, in which meat is occasionally consumed.
- Kangatarian