AGING BRAIN

HOW DOES THE BRAIN WORK?

The human brain is made up of 100 billion specialized cells called neurons (1).  These neurons receive neurochemical signals through branch-like structures called dendrites.  The main body of the cell then processes these signals and provides the energy, proteins, and chemicals necessary to relay additional signals.  These additional signals are passed down axons as electrical impulses until they reach terminals.  The terminals respond, in turn, by releasing neurochemicals (2).

Neurons can live for more than 100 years.  As a result, they must constantly maintain and repair themselves.  For this purpose, the brain also contains about 40-130 billion supporting cells called neuroglia (3).  These cells clear away cellular debris, provide nutrients to and insulate the neurons, support the blood-brain barrier, and protect against pathogens (4).

WHAT HAPPENS TO THE BRAIN AS WE AGE?

As we age, changes in our brains can affect our cognitive ability.  These age-associated changes are generally the result of one of two things:

1. The natural maturation process (referred to as normal aging)
2. Non-normative factors like disease or trauma (referred to as pathological aging) (5,6)

Both kinds of aging are associated with structural (7), chemical (8,9), physiological (10,11,12), and genetic (13,14,15) changes in the brain.

Defining the line between normal brain aging and pathological brain aging is difficult, and it is not yet entirely clear where one ends and the other begins.  Generally, the following occurs as the brain ages.

• Reduced blood flow and decreased vasculature in certain areas of the brain.  Damage to brain vasculature and to the blood-brain barrier are also common, but these are regarded as pathological changes (i.e. from high blood pressure etc.)
• Decreased glucose uptake and reduced glucose transportation (i.e. by insulin-sensitive transporters)
• Increased mitochondrial dysfunction and damage
• Increased reactive oxygen species and subsequent oxidative stress
• DNA damage in neurons and mitochondria
• Increased inflammation of the brain
• Certain neurochemicals and neurochemical receptors also decrease in the aging brain (7,8,9,10,11,12,13,14,15)

RISK FACTORS FOR AN AGING BRAIN

• Increased age
• Low education
• Medical conditions like diabetes, hypertriglyceridemia, or hypertension
• Excessive alcohol intake or smoking
• Limited physical activity
• Poor diet
• Depression
• Chronic inflammation (16,17,18,19)

SYMPTOM OF AN AGING BRAIN

The symptoms are generally the same whether normal or pathological aging occurs.  However, symptoms in pathological aging are generally more severe.

• Reduced ability to tune out or ignore irrelevant information
• Difficulty multitasking
• Difficulty processing and learning new information
• Increased difficulty finding words and recalling names
• Mild decreases in the ability to pay attention
• Slower processing speed (20,21)

AGING BRAIN FACTS AND STATISTICS

It has been estimated that the number of Americans over the age of 65 will double between 2010 and 2030 compared to the year 2000. By 2030 there will be about 72.1 million seniors in the United States which is twice the number from 2007 (22).

According to the United Nations, 1 out of every 10 people globally is age 60 or older, and the United Nations predicts that this number will grow to 1 in 5 by 2050 and 1 in 3 by 2150 (23).

The brain loses about 0.2-0.5% of its weight or volume every year after age 40.  Age-related decline in volume is not uniform across the brain and certain regions seem to shrink at a faster rate than others (24).

Alzheimer’s is the most common cause of dementia among older adults.  In 2013 an estimated 5 million Americans were living with Alzheimer’s disease. The number of people living with Alzheimer’s doubles every 5 years beyond age 65 (25)

MEDICAL TREATMENT OF AN AGING BRAIN

Treatment depends on what type of aging occurs.  There is little treatment for those who experience normal aging.  However, treatment of pathological aging varies greatly based on what disease someone is experiencing (26).

The following medications are usually prescribed for the diseases below:

• Alzheimer’s disease: Cholinesterase inhibitors sold under trade names Aricept, Exelon, and Razadyne, as well as memantine which is sold under the trade name Namenda, are prescribed to treat the cognitive symptoms of Alzheimer’s disease. Cholinesterase inhibitors are usually prescribed for the early stages of the disease, while memantine is prescribed for the later stages of the disease (27).
• Parkinson’s disease: Levodopa is the single most effective medication to treat the symptoms of Parkinson’s disease, but not the disease itself (28).
• Huntington’s disease: Tetrabenazine, Haloperidol, and Chlorpromazine are usually prescribed to suppress certain involuntarily movements, hence their primary role is to suppress the symptoms and not cure the disease. At this point, no medication for the treatment of the disease is identified (29,30,31).

NATURAL WAYS TO SUPPORT AN AGING BRAIN

Practices to Help Support an Aging Brain:

• Education: The most important and widely agreed upon item is education (32,33) and staying mentally active into years of elder life (34). Education has been shown to slow down age-related cortical thinning which in turn affects many cognitive functions (33).
• Physical activity: Exercise is another important factor which leads to increasing the neuroplasticity in the brain and hence improve cognitive function such as working memory, reasoning, response time and task switching (35,36,37,38). Physical exercise, when paired with mental exercise was shown to help increase the amount of gray matter and hence improve cognitive functions with a different mechanism (39,40). In fact, even in elderly with a sedentary lifestyle, short-term aerobic exercise is shown to boost cognitive performance (41). Exercise is also shown to fight neurodegenerative disease in early stages (42).
• Training: Brain training for certain cognitive function was shown to improve that function in long-term. Examples of such cognitive functions are selective attention and auditory attention (43).
• Early screening for neurodegenerative disease also helps with mediating the symptoms in pathological aging (44)
• Avoid smoking (45)

Natural Supplements to Support an Aging Brain:

• Phosphatidylserine (28,29,30,46)
• Vinpocetine (35,36,37)
• Bacopa (38,47,48,49,50,51)
• Ginkgo biloba (52,53)
• Ginger (54,55,56)
• Spearmint extract (57,58)
• Acetyl-L-carnitine (59,60,61)
• Ginseng Panax (62,63)

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