Dementia

What does the term dementia mean?

Dementia is a clinical condition characterized by a chronic, acquired cognitive impairment that affects several higher functions and significantly interferes with daily activities.

To understand this definition we will analyze its components:

• The acquired origin of dementia differentiates it from mental retardation and other congenital developmental disorders.
• The chronic course, arbitrarily defined as longer than 6 months, makes it possible to differentiate dementia from acute confusional syndrome.
• The requirement of impairment of several higher functions distinguishes dementia from focal syndromes. Years ago it was required that one of the altered functions was fixation memory, but nowadays it is not a necessary requirement.
• The presence of significant functional impairment differentiates dementia from mild cognitive impairment.

What is the frequency of dementia in the population?

The incidence (new cases) and prevalence (existing cases) of dementia increase exponentially with age. The prevalence of dementia in those under 65 years of age is less than 5%, while in those over 85 years it reaches figures of 30-60%. Given the progressive aging of the population and the costs associated with these pathologies, dementia is one of the main public health challenges in Western countries.

What are the main causes of dementia?

The causes of dementia can be classified into two major ones:

• Primary, idiopathic or degenerative dementias represent the dominant group in our environment. These processes are characterized by a slowly progressive course and the presence of brain deposits of abnormally folded proteins. Most cases are sporadic, but may have a genetic origin. The most frequent degenerative dementias are Alzheimer’s disease, dementia with Lewy bodies and frontotemporal degeneration.
• Secondary dementias occur as a consequence of structural neurological lesions or defined general diseases. The most frequent entity in this group is vascular dementia. Other important causes include normotensive hydrocephalus, hypothyroidism and vitamin B12 deficiency. Identification of these processes allows initiation of specific treatment and, in some cases, stabilization or reversal of cognitive impairment.

Overall, Alzheimer’s disease is estimated to cause 60% of dementia cases. However, the relative frequency of the causes of dementia varies greatly depending on age. In early-onset cases, genetic and secondary causes (e.g. trauma, infections, cerebrovascular disease) predominate. In those over 65 years of age, most cases correspond to degenerative or vascular dementias.

What are the symptoms of dementia?

Most patients with dementia present with subtle clinical manifestations for years. The first symptoms usually correspond to subjective memory complaints. Later they develop mild cognitive impairment, characterized by objective disturbances in one or more cognitive spheres without significant interference in social and occupational activities. Dementia would represent the final phase of this continuum, and in turn includes different stages of severity until complete dependence.

In clinical practice we observe two characteristic forms of presentation of dementias:

• Cortical dementias, the prototype of which is Alzheimer’s disease, are characterized by early impairment of fixation memory and the development of classic cognitive syndromes such as aphasia, apraxia and agnosia. In the early stages these patients usually do not have prominent motor manifestations.
• Fronto-subcortical dementias, typical of parkinsonisms and cerebral ischemic small vessel disease, are characterized by bradypsychia, alterations of executive functions and the presence of prominent motor disturbances from the onset.

How are patients with dementia studied?

The assessment of a patient with cognitive or behavioral symptoms begins with the clinical interview (anamnesis). In these cases it is essential to obtain additional information from a family member or cohabitant. We should collect the list of symptoms, paying special attention to their order of appearance and speed of development.

The anamnesis is followed by a physical examination, which in these cases should include a detailed examination of the mental status. The level of consciousness, attention, orientation, recent and remote memory, language, visual recognition, execution of motor acts, abstraction capacity, constructive skills and executive functions should be explored in an orderly manner. We should also investigate the mood and functional capacity of the patients. Validated scales and questionnaires should be used to facilitate the systematic collection of this information.

Once the clinical evaluation has been completed, several complementary examinations are usually requested. Essential complementary studies include:

• Blood tests: CBC, ESR, general biochemistry and levels of vitamin B12, folic acid and TSH.
• A brain imaging test, preferably MRI. The classic role of neuroimaging is to detect secondary forms of dementia, especially potentially treatable causes such as adult hydrocephalus (“normotensive hydrocephalus”), chronic subdural hematoma and tumors.

The remaining complementary explorations are performed only in selected cases, depending on clinical suspicion: immunological and microbiological analyses in blood and CSF, quantification of Aβ-42, tau and phosphorylated tau in CSF, EEG, genetic analyses, brain PET (FDG, ioflupane, amyloid markers) and other studies aimed at ruling out general diseases (e.g. occult neoplasms).

What is the treatment of dementia?

The ideal treatment would be aimed at eliminating the underlying cause and reversing the brain damage produced up to that point. Currently this therapeutic option is only possible in some cases of secondary dementia, such as certain metabolic disorders (e.g., vitamin B12 deficiency, hypothyroidism) and some structural neurological lesions (e.g., hydrocephalus, subdural hematomas, tumors).

In patients with degenerative dementias, treatment is limited to symptomatic measures. In particular, patients with Alzheimer’s disease and dementia with Lewy bodies may benefit from anticholinesterase drugs and memantine.

• Anticholinesterase drugs (donepezil, rivastigmine, galantamine) block the activity of the enzyme acetylcholinesterase, responsible for the degradation of acetylcholine, thereby increasing intracerebral levels of this neurotransmitter.
• Memantine blocks NMDA-type glutamate receptors, which reduces excessive calcium entry into neurons, resulting in neurotoxicity.

Apart from these specific treatments, most patients require medications aimed at improving affective and behavioral symptoms. These medications are the same as those used in various psychiatric illnesses (antidepressants, anxiolytics, neuroleptics), although low doses are usually used in this context.

What are the non-pharmacological treatments for dementia?

Non-pharmacological treatments are essential to improve the quality of life of patients and their caregivers.

First of all, it is advisable to follow a Mediterranean diet, rich in fruits and vegetables and low in sugar and saturated fats. It is also advisable to avoid the consumption of tobacco, alcohol and other toxic substances.

Secondly, regular exercise, such as a daily walk of at least 30 minutes, is recommended.

Thirdly, patients should remain mentally active to the best of their ability. In this regard, it is important that activities are regulated so that they are neither too simple (which is not stimulating) nor too complex (which would cause frustration). For this purpose it is advisable to follow the indications of a neuropsychologist.

Fourth, patients should continue to participate in social activities, as long as these activities are not stressful or behaviorally disruptive.

Finally, it is very important for the primary caregiver to seek help to avoid burnout. Apart from health center social workers, family caregiver associations are an excellent source of information in this regard.

How can clinical trials or other dementia research studies be accessed?

For years there has been intense research activity in the field of dementias. To participate in these studies, it is advisable to contact a neurologist expert in dementias, who will tell you which studies are underway and, if necessary, can direct you to other professionals. On the other hand, to obtain information through the Internet you can access some of the pages where ongoing clinical trials are registered (e.g. www.clinicaltrials.gov).

AUTHOR AND DATE OF ISSUE

Dr. Adolfo Jiménez Huete

18/05/2020