How meditation effects the Brain
As we go through life, our brain is always changing and adapting, say neuroscientists. During the first 18-20 years of life the brain is developing circuits that will form the basis of decision-making for a lifetime. Brain researchers have found that unhealthy lifestyles can inhibit normal brain development in adolescents and lead to impaired judgment and destructive behavior that carries over into adulthood. 
Studies recently published in the neuroscience journal Cognitive Processing show that brain development can be enhanced—not only during adolescence but at any age—through the Transcendental Meditation technique, and that different meditation techniques have different effects on the brain. Read more

Preventing Alzheimer's
Lifestyle factors such as stress, lack of physical and mental exercise, diet and routine are some of the main risk factors for developing Alzheimer’s. Addressing the onset of dementia or mental deterioration through preventative measures such as a meditation practice can go a long way in maintaining mental agility. Research findings on the Transcendental Meditation technique show increased blood flow to the brain, greater EEG coherence and more efficient, integrated brain functioning. Better education about the risk factors for Alzheimer's and the options for prevention should be part of this discussion. Read more about meditation and brain fitness ..

EEG Coherence in meditation
Some meditation techniques have been found to increase grey matter in the brain. What's more significant than changes in gray matter (which can happen by playing music or repeated mental tasks), is the brain research showing that meditation can change how the brain reorganizes it's neural networks, toward more coherent, integrated functioning.