Dementia can be prevented

The Lancet commission on “Dementia Prevention, Intervention, and Care” has identified essential measures that will reduce the risk of the disease.

Dementia causes memory loss, language and speech difficulties, social isolation, mood changes, agitation, delusions

In an article published last July in The Lancet, an expert commission has defined the main risk factors for dementia and has pointed out the most effective methods to prevent and treat this disease.

Dementia affects nearly 50 million people in the world (47 millions were estimated in 2015). As our longevity increases, this number is bound to triplicate by 2050 if we don’t take any preventive measure. Dementia generally occurs in people older than 65 years.

In 2015 about 47 million people suffered from dementia, a figure bound to raise if we don’t promptly adopt any measures to prevent it

The key point, as stated by the expert panel, is that “dementia is by no means an inevitable consequence of reaching retirement age, or even of entering the ninth decade”.

In other words: dementia can be prevented.

Prevention requires reducing dementia risk factors during the whole course of life.

What is dementia?

There are different types of dementia, with distinct physical causes and biological features. The most common forms of the disease are: Alzheimer’s disease, vascular dementia, dementia with Lewy bodies, mixed dementia (with traits of more than one forms), dementia associated with brain traumas, infections, alcohol abuse.

The most common symptoms of dementia are: cognitive decline (memory loss, difficulties in speech and in critical thinking), frequent mood changes from depression to euphoria, agitation, psychosis (delusions, delirium, sometimes hallucinations), sleep disturbances.

Mild cognitive decline is not dementia.

Mild cognitive decline occurs in about one fifth of people older than 65 years. It is characterized by some memory impairment and decreased quickness of thought, but it allows people who are affected to go on with their normal activities, which will require just a bigger effort or some new strategies.

However, mild cognitive decline is a risk factor for dementia and, as such, it must be treated to prevent its progression.

A normal brain (left) and a brain suffering from Alzheimer’s disease (right):in the latter, cerebral cortex and hippocampus appear shrinked

Risk factors for dementia

The main risk factor for dementia is age, which, of course, is not modifiable. However, its power might be reduced by acting on other factors.

In other words, it might be possible to push further the age at which dementia occurs today – i.e. beyond 65 years – by mitigating other risk factors for the disease.

Genetic factors linked to some forms of dementia are not modifiable at present.

Modifiable risk factors for dementia prevention. Dementia prevention implies reducing its risk factors.

What risk factors can be modified?

The Lancet commission has identified 9 risk factors that, when present, significantly increase the possibility of dementia in old age. All these 9 risk factors can be targeted and reduced:

MODIFIABLE risk factors for dementia


It is possible to prevent dementia by modifying the above risk factors and, thus, by increasing the brain cognitive reserve.

Dementia prevention and cognitive reserve

The brain cognitive reserve is the functional capacity of the brain, i.e. the brain’s capacity to activate and regulate the neural circuits that mediate cognitive processes: memory, imagination, reasoning, and so on.

A large cognitive reserve increases the brain’s ability to perceive reality and adequately react to it: it endows the brain with a more diverse array of neural circuits that can be modulated and coordinated to carry out everyday tasks and to respond to challenges. A brain with a large cognitive reserve can better adapt to, and manage different situations: it is more resilient.

Activated brain neutrons (in red) communicate with each other through synapses (the connection points between neutrons). Image by

The brain cognitive reserve is modifiable because the brain is plastic: its cells (neurons) can form new connections (synapses) and establish new circuits that regulate our cognitive functions throughout life.

Cognitive reserve and the risk factors for dementia

By increasing our cognitive reserve, we reduce our risk of dementia in late life.


A resilient brain has more functional options: if one neural circuit gets damaged, it is able to activate alternative circuits that can efficiently substitute for the damaged one.

How to increase the cognitive reserve? The Lancet commission explains that it’s possible to increase the cognitive reserve by taking on behaviors that limit or reduce the 9 risk factors indicated above.

These behaviors should become habitual and thus constitute a lifestyle, that ideally should be adopted since childhood.

Possible preventive interventions

Education: school education, study, and reading increase the cognitive reserve because they stimulate critical thinking and thus brain plasticity. It should be protracted beyond school years. Education also means teaching healthy habits, from healthy nutrition to regular physical activity.

Hypertension, obesity, diabetes must be controlled because they may cause directly (hypertension) or indirectly (obesity and diabetes) vascular damage in the brain and thus compromise its function, with a reduction of the cognitive reserve.

Reducing dementia risk: healthy diet, regular physical activity, mental and social activity, care of hearing

Hearing loss: several scientific studies have shown that hearing loss since midlife is associated with increased risk for dementia. This is probably due to multiple causes, including changes in brain activity because of reduced sound stimuli, and difficulties in social interactions and consequently a tendency to social isolation and possibly depression. Hearing aids and initiatives that promote social interactions can help stabilize and improve the cognitive reserve.

Physical exercise: Various studies have observed that the practice of physical exercise is inversely related to the risk of dementia: more regular physical activity throughout life is associated with lower risk of dementia in old age. In addition, older people who regularly engage in physical exercise have a higher probability to maintain normal cognitive abilities than people who are physically inactive.

Gymnastics Park Morning Qi Gong
A form of gentle physical exercise

The importance of physical exercise in dementia prevention

A series of scientific studies has found that aerobic exercise (which improves the cardiorespiratory function) and resistance training (which increases muscle force and resistance) are the most beneficial to cognitive capacities: the former especially to memory, the latter to reasoning capacities. Also Tai Chi, a type of physical exercise that harmoniously combines slow movements with breathing, improves attention and processing speed.

Clearly, any exercise program must be adapted to age, physical conditions, and health status to be beneficial and improve the cognitive reserve.

But how does physical exercise reduce the risk of dementia?

Besides improving muscle tone and cardiovascular function, and reducing the risk of obesity and diabetes, regular physical activity exerts direct effects on the brain:

  • it increases the blood flow to the brain
  • it promotes the release of chemicals that protect brain neurons and stimulate neurogenesis and brain plasticity.

Physical exercise directly increases the cognitive reserve by remodeling the connections between neurons, and by improving the brain’s functional capacities.

In fact, a study in healthy adults, aged between 55 and 80 years, has demonstrated that walking for 40 minutes three times a week for a year increased the size of the hippocampus (a brain structure implicated in memory) and improved memory.

It is demonstrated that regular physical exercise is associated with better cognitive abilities and greater brain health; however, there is not enough scientific evidence yet that physical exercise protects against diseases (Alzheimer’s disease, dementia with Lewy bodies etc.) that cause dementia. Studies to clarify this point are ongoing.

Conclusions from the Lancet commission

Dementia can in large part be prevented.

A healthy lifestyle increases the brain’s cognitive reserve, its ability to adapt and react to different challenges, and to maintain its functional capacities.

Besides avoiding certain behaviors like unhealthy eating (that favors hypertension, obesity and diabetes) and smoking, the Lancet commission recommends taking on activities and adopting behaviors that stimulate the plasticity of the brain.

Among these activities, the most important and effective are:

  • prolonged education (beyond school years and ideally throughout life)
  • treatment of hearing problems
  • regular practice of physical exercise


“Dementia prevention, intervention, and care”, G. Livingston et al., The Lancet (2017)


Deep brain stimulation: Temporal Interference stimulation, a new, non-invasive technique to treat nervous and psychic disorders

A new technique allows the stimulation of precise areas deep in the brain by applying electric currents on the scalp, with no need to introduce electrodes into the brain. Its potential therapeutic applications include the treatment of both movement disorders, such as Parkinson’s disease, and psychic conditions, from depression to bipolar disorders.

Image: modified from Wikimikedia Commons staff 

Abnormal electrical activity in the brain underlies various motor and affective disorders. The former include Parkinson‘s disease, tremor, dystonia (characterized by uncontrollable and repetitive muscle contractions); among the latter are depression, bipolar disorders, obsessive-compulsive disorders.

These conditions are normally treated with drugs that modulate the electrical activity of the brain through a chemical stimulus (i.e. the drug molecule acting on brain cells); unfortunately, drugs always produce upsetting side effects that are often quite severe.

Transcranial electrical stimulation

A new therapy employs electrical currents to modulate the electrical activity of structures located deep inside the brain. We’re not talking, of course, about the comeback of electroshock (have you seen “Somebody flew over the cuckoo’s nest?”), but about applying currents of a specific intensity to specific brain areas.

In this way, the treatment is limited to a certain region (as opposed to diffuse over a large area), and secondary effects are significantly reduced or even eliminated.

Today this therapy, called transcranial electrical stimulation, is administered by introducing electrodes into the brain near the target area to be treated: clearly this technique is invasive and presents serious risks, and as such it’s employed only for those patients that do not respond to drugs.

Transcranial magnetic stimulation

A similar therapy, called transcranial magnetic stimulation (TMS), consists in administering a magnetic impulse to the head, i.e. on the scalp, and does not require surgery. This impulse induces an electrical current beneath the skull on the brain surface, which, however, can stimulate only superficial areas of the brain cortex and can’t reach structures located more deeply.

By applying sequences of magnetic impulses (repetitive TMS, or rTMS) it is possible to treat some forms of depression that are resistant to other therapies.

Some good news: a non-invasive technique for deep brain stimulation

Research keeps moving on and a study that was published this month in Cell (Grossman et al.) describes a technique that allows to modulate electricity deeply in the brain by applying currents to the scalp, with no need to surgically introduce electrodes.

This technique is called Temporal Interference stimulation.

Waves interference. Image from

How does it work?

This method is based on the concept of interference of electrical fields: two currents with similar frequencies (only slightly different) create electric fields that, when intersecting, combine and produce a new field that oscillates at a low frequency, equal to the difference of the two initial frequencies.

For example, if the two original fields differ in frequency by 10 Hz (as in the Cell study), the new, resulting field will oscillate at 10 Hz.

The frequency of the resulting field in a specific point will depend on the electrode position and on the currents that are applied to the electrodes: clearly, it can be easily modulated.

Thanks to the properties described above, the new technique allows to suitably place the electrodes on the scalp and choose the currents so to produce a specific frequency in the brain area that needs treatment.

The technique

The technique was established by a research group from the Institute for Brain Research, MIT (Cambridge, USA) who carried out the experiments in mice. The researchers put two electrodes on the animals’ heads (on the skin) and then applied two slightly different currents.

The chosen currents were unable to stimulate brain areas near the electrodes, but, because of interference, they generated a new electric field in a limited area inside the brain, at the right frequency to stimulate neurons.

The result was that only neurons in that area responded to the field and became “activated”, whereas neurons outside the area remained “at rest”.

The experiments

For example, by conveniently modulating the initial currents applied to the electrodes, the researchers were able to activate specific areas of the mice motor cortex and cause movement either in a paw or in the whiskers of the animals.

By further changing the currents in another experiment, the researchers could reach and specifically stimulate the hippocampus, a structure that is located deep inside the brain, without activating other more superficial areas.

The hippocampus is located deep inside the brain and is implicated in memory. Image modified from

A therapeutic revolution on the horizon

This new study expands the therapeutic potential of transcranial electric stimulation and corroborates the possibility to cure various neurological disorders with no need of drugs or of invasive surgical procedures.

In fact, we can now easily imagine that in a not so far future, doctors will be able to treat patients by placing electrodes on their scalp and applying suitable currents so to stimulate one or more target brain areas and normalize their electrical activity.

This therapy will benefit patients without causing those wearing side effects that are always associated with drugs.

This technique could treat nervous and psychic disorders:

  • by reducing or eliminating uncontrollable spasms and tremors, and thus alleviating Parkinson’s disease and other illnesses that are characterized by movement dysfunctions;
  • by stabilizing the activity of those brain structures that, when perturbed, cause affective and behaviour disturbances, like, among others, depression, bipolar disorders, and obsessive-compulsive disorders.
Electrodes are applied on the scalp; appropriate currents stimulate areas located deep inside the brain. Image modified from Wikimedia Commons

The technique needs of course more research before it can be applied to human patients: the researchers will have to evaluate its safety in the short and long term, and will have to make it extremely precise for the treatment of each single case.


“Noninvasive Deep Brain Stimulation via Temporally Interfering Electric Fields” N. Grossman et al., Cell 169, 1029-1041 (2017).

“Translational principles of deep brain stimulation” M. L. Kringelbach et al., Nature Rev Neuroscience 8, 623-635 (2007).


When the mind wanders

Scientists have identified cerebral circuits that are activated (or deactivated) any time we engage in spontaneous thought and let our minds wander freely. These circuits are turned on also when we are involved in imagining and creating something, or when we dream while asleep. Interestingly, they are perturbed in people suffering from various conditions including anxiety, depression, attention deficit hyperactivity disorder (ADHD), and others.

In the future, researchers hope to develop new therapies for psychological and behaviour disorders that will employ electromagnetic waves to regulate the activity of these brain networks efficiently and without drugs.


You are working on something, your attention absorbed by the task, when suddenly you realize that your mind has wandered off and you’re now thinking of something totally different: tonight dinner party, the vacation you long for, that great book waiting for you on your bedside table…

Your mind just took off from the job and is now wandering.

When the mind wanders, we become detached from things happening around us, and enter a mental state that reflects the content of our rambling thoughts: desire, confidence, fear, wonder…

Mind-wandering is an example of spontaneous thought, like dreaming and creativity.

Spontaneous thought is “free” thought: it is free of those constraints that we usually apply to our thinking to make it logic and goal-directed.

In mind-wandering, we let our thought unfold and we follow it in its wondrous flights.

Deliberate and automatic constraints

When we are engaged in any task requiring our attention, we apply constraints to our thoughts. These constraints can be deliberate (to evaluate, criticize, summarize, understand, and so on), or automatic (independent of your will, we just can’t ignore them).

A couple of examples to make it clearer:

We are working, but we can’t help checking our email any time we hear the beeping sound informing us that we got a new message: this is an automatic constraint.

We are reading a complicated and detailed instruction booklet and, despite we find the explanations difficult to grasp, we keep our concentration on it, committed to understanding every sentence: this is a deliberate constraint.

Constraints in the three types of spontaneous thought

Mind-wandering has more deliberate constraints than dreaming, but less than creative thought. Automatic constraints are low for the three types of spontaneous thought.

We can thus say that dreaming is the most spontaneous among free thoughts, followed by mind-wandering, and then by creative thought.

It’s interesting to notice that creative thought has some deliberate constraints because at the same time it is directed toward freely imagining (inventing) and creating (turning ideas into matter), the latter goal requiring critical evaluation and determination.

adapted image by lloveart lloveart

But how does the mind wanders?

What type of brain activity supports our flights of thought?

Scientists have identified some brain regions whose activity varies significantly during mind-wandering. These regions are part of brain circuits that are mostly localized in the brain cortex, are interconnected, and are functionally linked to some subcortical centers inside the brain.

The circuits that sustain spontaneous thought

The main brain circuits involved in mind-wandering are:

the Default Network (DN): it includes the DNcore that is activated when our thoughts are internally oriented (and deactivated during tasks that require our interaction with the external environment); and the DNMTL that is centered around the medial temporal lobe and is involved in memory and imagination of sceneries and possibilities (i.e. in “constructive mental simulations”);

the Dorsal Attention Network (DAN) and Ventral Attention Network (VAN) that acquire information from the external world and send it to motor centers to regulate body movements;

another “salience” network that catches relevant elements in the environment like DAN and VAN, and in addition is stimulated by perceptions and emotions that appear particularly prominent;

the frontoparietal control network (FPCN) that sustains critical thoughts regarding both the internal world (for instance evaluations about an important decision) and the external environment.

by houseofwhacks

Brain activity during mind-wandering

When our minds wander, DN activation predominates. In other words, DN centers sustain the free flights of our minds.

It’s in particular the DNMTL that is very active and produces ideas and spontaneous visions that are in part based on our memories stored in the hippocampus.

Moreover, the centers that limit our free thought by focusing our attention on details of the internal and external worlds (DAN, VAN, salience network, FPCN) are turned off.

And when we dream?

Tests on sleeping people have shown that during the REM phase of sleep (when we mostly dream), DNMTL is very active, FPCN is inactive, and DNcore doesn’t change its activity compared to the wake state.

This activation pattern is similar to the one observed during mind-wandering, but the levels of activity in the different networks, as well as the interactions among them, are probably different during the two types of spontaneous thought, and subtly modulated. In this way, during dreaming deliberate constraints are reduced to a minimum, and automatic constraints are kept low.

And what happens in the brain when we are creating something?

In a recent study researchers examined the brain of artists while they were drawing. They observed that there was a continuous shift in network activity, from periods of high DNMTL-activity and low DNcore and FPCN-activity, to periods in which the DNcore and the FPCN were on and the DNMTL was off.

This alternation corresponds to different phases in the creative process, namely the artist’s moving from grasping his/her creative “vision” and intuition, to critically evaluating them and turning them into concrete matter.

Analysis of spontaneous thought networks in the clinics

Knowing how brain activity changes during spontaneous thought has important implications in the clinics. In fact, spontaneous thought is altered in people suffering from various conditions, including anxiety, hyperactivity, depression, schizophrenia.

For example, excessive spontaneous thinking (which corresponds to the inhibition of the brain circuits that induce constraints, and to the hyperactivation of those that sustain free thinking) contributes to mental restlessness and to the inability to stay focused.

On the other hand, excessive constraints make thinking fixed, repetitive and “obsessive“, as it happens with rumination, which is typical of both anxiety and depression.

Analysing the activity of brain networks that control spontaneous thought can thus be very useful in the diagnosis of psychological and behaviour disorders.


Therapeutic modulation of spontaneous thought to treat psychological and behaviour disorders

But this is not all. Scientists envisage a future when it will be possible to specifically modulate brain activity so to either disrupt obsessive thought (and so treat anxiety, depression and various psychogenic disorders that are characterized by rumination), or stabilize thought and increase focus and critical abilities (and so treat ADHD and disorders characterized by frequent mood changes).

The new therapies will employ electromagnetic waves and not drugs: they’ll be targeted and will have less side effects than drugs.

All this will require further research to better understand the interactions among the different brain networks that regulate spontaneous thought.


“Mind-wandering as spontaneous thought: a dynamic framework”, K. Christoff et al., Nature Rev Neuroscience 17, 718-731 (2016).

What is STRESS?

We spontaneously react to adverse conditions by becoming alert and focused, and by taking action to overcome the difficulties we face and regain a state of quietness and balance.

If the adversities persist and we are unable to find a solution, we slowly exhaust our physical and mental resources and become weak and frustrated: in other words we become stressed.

Chronic psychophysical stress is a state of physical and mental exhaustion that arises when we are unable to resolve a difficult situation, despite various attempts.

Stress hits the body and the mind: we feel tired but often can’t sleep enough, and we feel hopeless.

Stress impacts our immune system and opens the doors to physical illnesses: from cardiovascular disease, to digestive and respiratory dysfunctions, depression and even cancer.

Several behavioral techniques that do not imply the use of drugs are very effective in preventing and treating psychophysical stress.



“Stress revisited: A critical evaluation of the stress concept”, J.M. Koolhaas et al., Neurosci Biobehav Rev 35, 1291-1301 (2009).

“Glucocorticoid regulation of inflammation and its functional correlates: from HPA axis to glucocorticoid receptor dysfunction” M.N. Silverman, E.M. Sternberg, Ann NY Acad Sci 1261, 55-63 (2012).

“The effects of chronic stress on health: new insights into the molecular mechanisms of brain-body communication” A. Mariotti, Future Sci OA 1, FSO23 (2015).

“Stress-induced immune dysfunction: implications for health” R. Glaser, and J.K. Kiecolt-Glaser, Nature Rev Immunol 5, 243-251 (2005).