Neurological Disorders: Dementia

Dementia is a neurological condition and manifests with chronic mental (thinking or cognitive) deficits, significant enough to affect somebody’s functioning of daily life. In the beginning it may be subtle however as time passes it affects personal, family, social and occupational spheres of patient’s life and also get noticed by others. A Neurologist is frequently involved in the care of these patients.

If the duration is short then the above term is avoided, rather depending upon what we are dealing, terms like delirium or encephalopathy etc are entertained.

The term “mental” can be confusing sometimes; “mental patient” is an expression generally used for patients with psychiatric problems. But in the expression “mental abilities” the term implies of the cognitive & intellectual abilities of an individual rather than the psychological aspects of thinking and this is the connotation applied in this article.

Some misconceptions about dementia

1) It is always non-reversible

No it is not true. The definition doesn’t require whether the condition is reversible or not. In fact there are several reversible types (see later). But it is also true that the vast majority of them are indeed non reversible.

2) It is always progressive

No, this notion is wrong too. There are certain types that are static and never progressive (see later).

3) It brings certain and a quick death

Nope again; as cited above there are reversible and static types so this diagnosis is not at all a certain death warrant. Also many of the progressive types do so slowly rather than deteriorating at a galloping phase.

4) It occurs only in old people, and mental retardation is another term for it.

Wrong again. It can affect other adults (middle age, young adults), adolescents & children too, but it is true that it predominantly affects older individuals.

By definition, dementia means, losing “the already acquired mental faculties”. Mental retardation is the preferred term when someone’s mental faculties were never developed normally. So somebody born with a dementia like picture can only be called as mental retarded, but not demented whatever caused the intellectual disability.

Similarly if somebody loses cognitive abilities after acquiring them, then it cannot be called as mental retardation.

There could be some overlapping age, during especially childhood, where whether dementia or mental retardation is the preferred term but a careful history can resolve it.

Isolated memory loss is not enough to make a diagnosis of this condition and there should be at least one more cognitive sphere dysfunction including language skills, apraxias, agnosias, decreased insight, judgment, deficits in executive functioning, abstract thinking etc.

Apraxia means an inability to perform previously learned motor activity despite having the physical ability & desire to do so. Agnosia is a loss of a person’s ability to recognize things by using the special senses like vision, hearing, smell, taste etc while these senses themselves are intact.

Some important dementing conditions

Neurodegenerative conditions

• Alzheimers
• Dementia with Lewy bodies
• Vascular type
• Frontotemporal type
• NPH (normal pressure hydrocephalus)

Endocrine disorders;

Hypothyrpoidism

Nutritional deficiency;

• Vitamin B12
• Folic acid
• Niacin (Vitamin B3)
• Thiamine (Vitamin B1)

Classification of Dementing illness

It can be classified in many ways and some of them are mentioned below;

• Reversible e.g. hypothyroidism related
• Irreversible e.g. Alzheimers
• Progressive e.g. Alzheimer’s
• Non progressive (static) e.g. TBI (traumatic brain injury) related, postencephalitis related etc
• Rapidly progressive e.g. CJD (Creutzfeldt Jacob Disease)

Certain psychiatric conditions, for example depression can manifest as a dementing illness and this is called as pseudodementia. Generally this is a reversible condition; once the psychiatric cause is identified and promptly treated you would expect the dementing features melt parallely. But it is not always true, in some patients there may be only partial improvement, and sometimes no improvement at all.

If the clinical picture doesn’t give much clue as to what might be the possibility then myriad neurological tests may be required to arrive at the correct diagnosis. For conditions like AD the diagnosis is still mostly clinical although for hereditary forms genetic tests are indicated.

The following investigations may be required as a work up for dementing illnes (decided on case to case basis);

• CT and/or MRI of brain
• Thyroid tests
• Vitamin B12
• Folate
• ESR
• ANA
• Calcium
• EEG
• CSF (cerebrospinal fluid) analysis
• Genetic tests
• Brain biopsy etc

There are no curative treatments yet for dementing illness. If the cause for dementia is reversible like hypothyroidism, B12 deficiencies etc then patients are appropriately treated and the further cognitive worsening can be halted and some patients may even recover fully.

For dementia like AD symptomatic treatment is available in the form of Acetyl cholinesterase inhibitors (e.g. donepezil or aricept) and NMDA receptor antagonist memantin (namenda). They are not effective for every AD patients also only partial benefit may be seen. Some of these agents may be symptomatically useful for vascular dementia as well.