Mental Stimulation Is Crucial for Cognitive Enhancement
While our brains aren’t actually muscles, recent research shows one large similarity between them. As with your muscles, the brain grows and strengthens when challenged frequently, and weakens when deprived of stimulation. One interesting study showed that animals which lived in more mentally challenging environments grew heavier brains than animals that lives in less challenging ones. 
If you are serious about improving your intelligence and mental performance, then you must use nootropics in combination with regular mental exercise. Taking nootropics and spending all day watching television won’t do much for you. The best way to maximize your gains is to train all different areas of cognition. Different activities are best at training different aspects of cognition. Below is a list of some different areas of intelligence and the most effective ways to train them:
If your goal is into increase your fluid intelligence (what is measured in IQ tests), than training your working memory is one of the best ways to do so.  Working memory is your ability to temporarily store and use information in order to complete complex tasks. In a nutshell, the better your working memory is the easier time you will have making connections and solving problems.
One of the best ways to train your working memory is by playing the Dual-N-Back Test. This test was used in many different studies that looked at the link between working memory and intelligence. In some of these studies, it was successfully shown to improve IQ.  The test involves paying attention to shapes and sounds and becomes more challenging as you complete each stage.
You can play the Dual-N-Back test, and learn more about it here
Another excellent place to train your working memory is Lumosity. Lumosity is the largest and highest quality brain training site around. They have over 15 different games to train working memory, and their games are designed to improve your training while still being fun.
Processing speed is how quickly your brain can react to information it has been provided with. Having a fast processing speed helps out your working memory as it decreases the time your brain must hold a given piece of information in working memory. Research has proven that this link exists. 
Lumosity has a large variety of games which train your processing speed.
Also known as reasoning, your brain’s ability to solve problems can absolutely be trained and improved. The most important factors in improving your problem solving skills are novelty and challenge. Facing and overcoming problems and challenges you’ve never been exposed to before is the best way to improve your reasoning skills.
Creativity also plays a large role in the brain’s ability to solve problems. Improving the communication between the left and right hemispheres of your brain will allow you to combine logic and abstract thought in order to arrive at solutions to problems.
Puzzle games are one excellent way to train your ability to reason, however they are far from the only method. Learning math and computer programming languages are excellent ways to improve your problem solving skills, but even just exposing yourself to new situations can help.
Attention and Focus
Focus is the ability of the brain to concentrate on only one thing while not paying attention to other stimuli. Being able to focus well is essential for completing any type of complex or mentally demanding task. It is easy to improve your ability to focus on specific tasks by eliminating distractions or by using certain nootropics, but you can also train your mind to be able to focus better in general.
Playing brain training games designed to improve your focus is a great way to do this. As you repeatedly partake in activities that require high amounts of focus, you will have an easier time focusing in the future. Lumosity has a wide variety of different games designed to train your ability to focus.
When playing brain training games or performing other mentally stimulating tasks it is extremely important to always be challenged. When exposed to novelty and challenge your brain is working at its hardest and is forging many new connections. Once a particular game becomes too easy it’s time to ramp up the difficulty or move on to a different one.
As mentioned in our article on maximizing the effectiveness of nootropics, combining brain training games with a nootropic regimen will provide far greater benefits than either will alone.
8 ) http://www.sciencedaily.com/releases/2009/02/090210162039