The World Health Organization defines mental health as a “state of well-being in which the individual realizes his or her own abilities, can cope with the normal stresses of life, can work productively and fruitfully, and is able to make a contribution to his or her community”.
Dementia is one of the prevalent mental illnesses, which is more common in the elderly. Dementia, characterized by a decline in the functioning of the brain is an illness that results in the loss of mental functions like thinking, memory, reasoning and overall cognitive abilities. Some of the common symptoms of dementia include loss of memory, changes in personality, mood, and behavior.
Types of Dementia
Based on the portion of the brain affected - dementia is categorized into two main types, which are cortical dementia and sub-cortical dementia.
Cortical Dementias
These are dementias which are a result of a disorder in the cerebral cortex. The Alzheimer’s disease is one of the common types of cortical dementias.
However before you move on to read about cortical dementias, you need to know the functions of the cerebral cortex. The cerebral cortex is a structure within the brain, which is plays an important role in memory, perceptual awareness, language, thought, consciousness and attention. The cerebral cortex is comprised of three important parts, which are sensory, motor, and association areas. The sensory areas receive and process information from the senses, while the association areas function to produce a meaningful perceptual experience, process languages and thoughts and help us to interact effectively. The motor areas on the other hand help to execute and select voluntary movements.
Alzheimer’s Disease: Alzheimer’s disease, also known as Senile Dementia of the Alzheimer Type (SDAT) is an incurable, degenerative disorder and is one of the common types of dementia. Alois Alzheimer, a German psychiatrist was the first one to describe this disorder. During Alzheimer’s disease, the brain of the affected person shows characteristically abnormal behavior. The brain cells produce reduced amounts of neurotransmitters, which are chemicals required for communication between nerves. Some of the common symptoms or signs of Alzheimer’s disease include serious memory problems, which can affect everyday activities. Early diagnosis is crucial for effective treatment of the Alzheimer’s disease.
Dementia with Lewy Bodies(DLB): The dementia with Lewy bodies is characterized by the presence of Lewy bodies. The Lewy bodies are abnormal aggregates of protein, which develop inside nerve cells. Although the causes of this type of dementia are not well understood a locus at a gene called PARK11 is supposed to be associated with the disease. Several symptoms and pathology of DLB are similar to Alzheimer’s disease and the Parkinson’s disease. The diagnosis often involves detection of Lewy bodies, loss of dopamine-producing neurons and a loss of acetylcholine-producing neurons. People suffering from DLB exhibit fluctuating cognition with variation in attention and alertness, accompanied by hallucinations, syncope, transient loss of consciousness and hypersensitivity to neuroleptic medications.
Vascular Dementia: Vascular dementia, also known as multi-infarct dementia is a degenerative cerebro-vascular which is marked by a decline in the brain functions. Often, it is caused by a series of small strokes that damage the cerebral cortex and hamper understanding of language, instructions and the memory. Some of the early symptoms of vascular dementia also include mild weakness in the limbs, slurred speech, dizziness and impairment in the short-term memory. More prominent symptoms include prominent loss in memory, loss of control over bladder and bowel movements, difficulty in following instructions, lack of verbal fluency, a slowing of the processing ability and hampered abstract thinking.
Frontotemporal Lobar Degeneration(FTLD): Frontotemporal Lobar Degeneration refers to the group of disorders associated with atrophy in the frontal lobe and the temporal lobe of the brain. It is the fourth most common type of dementia. Clinically there are three subtypes of Frontotemporal Lobar Degeneration, which are frontotemporal dementia, semantic dementia and progressive nonfluent aphasia. Frontotemporal Dementia (FTD) is caused by degeneration of the frontal lobe of the brain and may extend to the temporal lobe. Semantic dementia (SD) is a progressive neurodegenerative disorder marked by loss of semantic memory. Progressive nonfluent Aphasia is marked by progressive difficulties with the production of speech.
Alcohol Induced Persisting Dementia: Also known as Alcohol Dementia, this disorder is associated with dementia resulting from excessive continuous consumption of alcohol. The common types of disorders in this category include the Korsakoff’s syndrome, Wernicke’s encephalopathy or the Wernicke-Karsakoff’s syndrome, which is a combined manifestation of first two disorders. Prominent symptoms of Korsakoff’s syndrome include anterograde amnesia, retrograde amnesia, confabulation, lack of insight and apathy, which are caused by thiamine deficiency. The onset of Wernicke’s encephalopathy is usually abrupt and is marked by gait ataxia, confusion, short-term memory loss, confabulation and several eye movement disorders. The Wernicke-Karsakoff’s syndrome exhibits combined symptoms of both the disorders. Some of the common signs include memory loss, difficulty performing familiar tasks, impaired judgment, problems with language and changes in personality. Unlike other forms of dementia, which are common only in elderly people, anyone (regardless of age) who is a regular heavy drinker is at risk for succumbing to alcohol related dementia.
Creutzfeldt-Jakob Disease: Creutzfeldt-Jakob disease (CJD) is a fatal degenerative neurological disorder. Known to be related to the mad cow disease, the symptoms of CJD are similar to those of Alzheimer’s disease, the only difference being that CJD progresses much faster. There are three types or variants, which are sporadic, hereditary and acquired. Sporadic form is the most common in which disease appears without exhibition of any risk factors. The hereditary case is the one in which person has a family history of CJD and tests positive for the genetic mutation that is associated with CJD. The acquired CJD is transmitted by exposure of brain or nervous system tissue. Initial symptoms include speech impairment, blurred vision, insomnia, personality changes, anxiety, and memory loss, impaired thinking and impaired muscle coordination as well. The symptoms aggravate as the disease progresses and in many cases the patient may lapse into coma. The disease becomes fatal and most common causes of death include heart failure, respiratory failure, pneumonia or other infections.
Dementia Pugilistica: Harrison S. Martland was the first to describe Dementia pugilistica in the year 1928. Dementia Pugilistica is also known as chronic traumatic encephalopathy (STE) or Boxer’s Dementia or the Punch-drunk syndrome. This is a neurological disorder, which is common in boxers and wrestlers owing to the repeated concussions during the matches. The most common symptoms include declining mental abilities, memory loss, tremors, lack of coordination, speech problems and pathological paranoia. The patient’s brain tends to lose neurons and the pyramidal tract in the brain becomes dysfunctional. Common causes that lead to this disorder are loss of neurons, hydrocephalus, collection of proteinacious and senile plaques, diffuse axonal injury, attenuation of corpus callosum, neurofibrillary tangles and damages to the cerebellum.
MoyaMoya Syndrome: The angiographic image for a person suffering from this disease looks like the “puff of smoke” which is how Moyamoya loosely translates from Japanese, and hence the name of the disorder. Moaymoya syndrome is a progressive neurological disorder, which affects the blood vessels in the brain. Moyamoya disease is characterized by the narrowing and/or closing of the carotid artery. Inadequate blood supply leads to decrease in the oxygen supply to the brain and remains to be the prominent causes of the Moyamoya syndrome. This disorder can either be congenital or acquired. Patients suffering from down syndrome, neurofibromatosis or sickle cell disease are vulnerable to Moyamoya syndrome. Diagnosis is usually done with the help of Computed tomography (CT), Magnetic resonance imaging (MRI) or an angiogram.
Benson’s Syndrome: Also known as the Posterior Cortical Atrophy, this syndrome is the visual variant of the Alzheimer’s disease and was first described by Franck Benson in 1988. This syndrome causes shrinkage of the cortex (which is the posterior part of the brain). The early symptoms of this disease usually start appearing after the age of fifty. Some of the early symptoms include blurred vision, problems with depth perception and difficulties in reading. As the disease progresses, the condition aggravates and the person might show mis-recognition of familiar faces and object or even suffer from hallucinations.
Sub-cortical Dementias
The second category of dementias is the sub cortical dementias, which are a result of dysfunction in the parts of the brain, which are beneath the cortex. The symptoms and signs of sub-cortical dementias differ largely from the cortical dementia disorders.
Huntington’s Disease: The Huntington’s disease is named after the American Physician George Huntington, who first described this disease in the year 1872. Huntington’s disease is a genetic neurological disorder, which affects the nerve cells in the brain and results in uncontrolled and uncoordinated body movements (called chorea), emotional disturbance and decline in overall cognitive abilities. Huntington’s disease is a trinucleaotide repeat disorder, which means that it is caused owing to the length of a repeated sequence of a gene, which exceeds the normal gene. The normal gene is called the Huntingtin gene and is referred to as HTT, while the mutant gene is referred to as mHTT. The symptoms for Huntington’s disease include chorea, slurred speech, and other psychological symptoms of dementia.
Dementia Due to Metabolic Abnormalities: In addition to several other reasons, there are a few metabolic abnormalities which can lead to dementia. Decreased thyroid function, which is medically termed as hypothyroidism results in depression that is similar to dementia. Hypoglycemia, which is a medical condition in which there is a lack of adequate sugar in the bloodstream, can cause confusion or personality changes. Pernicious anemia, which is caused by failure to absorb vitamin B-12 also can cause cognitive changes and lead to dementia. A condition called the beriberi disease, which is marked by deficiency of Vitamin B1 or Thiamine can also cause dementia. Folate deficiency can also lead to dementia.
Dementia Due to Parkinson’s Disease: Parkinson’s Disease is also known as Primary Parkinsonism or Idiopathic Parkinson’s Disease. Parkinson’s disease is a chronic and progressive neurodegenerative disorder, which affects the central nervous system (CNS) and results in impairment of the patient’s motor skills as well as other functions, which are controlled by the CNS. Parkinson’s disease is characterized by muscle rigidity, bradykinesia, tremor, and in some cases akinesia, which means loss of physical movement. All the symptoms in the Parkinson’s disease are a result of the degeneration of brain cells that produce dopamine, particularly those located in the locus coeruleus and the substantia nigra.
Dementia Due to Subdural Hematoma: Subdural Hematoma is a form of brain injury in which blood gathers between the outer protective covering of the brain (dura) and the middle layer of the meninges (Arachnoid). The bleeding separates the dura and the arachnoid layers and may cause a rise in the intracranial pressure (ICP), which can cause compression and damage to the delicate brain tissues. Signs and symptoms of subdural hematoma include history of recent head injury, loss of consciousness, amnesia, nausea, vomiting, numbness, dizziness, disorientation, blurred vision, Ataxia, personality changes, slurred speech, seizures and constant or fluctuating pain.
AIDS Dementia Complex: AIDS Dementia complex is a neurological disorder that is associated with HIV infection and AIDS. It is a metabolic encephalopathy, which is induced by HIV infection and caused by the immune activation of brain macrophages and microglia. AIDS Dementia Complex is characterized by impaired cognitive abilities, motor dysfunction, behavioral changes and speech problems. The cognitive disabilities usually include mental slowness, poor concentration and mild loss of memory. The motor symptoms include clumsiness, poor balance and tremors. The behavioral changes include lethargy, diminished emotional response and apathy. Dementia is diagnosed in the AIDS Dementia complex usually when the cognitive impairment in the patient is severe enough to hamper the routine day-to-day functions. The severity of the symptoms increases as the disease progresses. The normal, sub clinical and mild stages lead to moderate and severe cases and reach the severe stage in which the intellectual and social comprehension and responses are at a rudimentary level and the person becomes paraparetic pr paraplegic with urinary and/or fecal incontinence.
PsuedoDementia: Psuedodementia is a severe form of depression, which results from a progressive brain disorder in which cognitive symptoms mimic those of dementia. It is usually seen in older people in which the symptoms are similar to dementia but the cause is a pre-existing psychiatric illness and not a degenerative one. The history of disturbance in this disorder is short and abrupt onset unlike in dementia where it is more dangerous. Clinically, people with pseudodementia can be differentiated from those with dementia when their memory is tested since people with psuedodementia will often answer that they don’t know the answer to a question, and their attention and concentration are intact, and they appear upset or distressed. On the other hand people suffering form Dementia will often give wrong answers, have poor concentration, and will appear indifferent.
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