Dementia In Huntington Disease

Many times, when patients have symptoms, they initially go to a psychiatrist. After a detailed history and examination, you may have to refer the patient to a neurologist or medicine for integrated management of the patient. Patients can go to a psychiatrist first or go to a neurologist first; from there, they get referred to a psychiatrist managing the patient.

What is Huntington Disease?

Huntington's disease has motor and cognitive symptoms and psychiatric symptoms.

There may be a mixture of symptoms· The patient may come to you, and subsequently, you can

refer the patient, or you may get a referral from a neurologist regarding the management of this patient.

History

George Huntington first described Huntington's disease in 1872, and subsequently, it was named Huntington's disease. In 1993, the mutant gene responsible for Huntington's

disease was identified.

Etiology

It has an autosomal dominant transmission, and an important mutation has been identified, which is a triplet CAG repeat mutation in the HTT gene on chromosome 4. This leads to polyglutamate expansion in Huntington's protein. There is an abnormality in protein, which leads to neuronal damage and death, especially in areas like the caudate nucleus and frontal lobes.

Many of the symptoms are because of frontal lobe involvement and many of the subcortical areas involved, which lead to the symptoms.

Also read: Laboratory Tests For Traumatic Brain Injury

Diagnosis and Clinical Features

Motor Symptoms

Initially, chorea and ataxia are seen; that's why it is called Huntington's chorea. Subsequently, bradykinesia, dystonia, and ideomotor apraxia can be seen.

Cognitive Symptoms

Deficits in the visuospatial domain Psychomotor slowing can occur; Executive functioning, attention, and memory deficits.

Psychiatric Symptoms

Can also be present in the patient along with motor and cognitive symptoms. Personality changes - A lot of these will be related to frontal lobe involvement.

• Depression, irritability
• Psychosis
• Sometimes aggressive-compulsive behavior (some repeated behaviors may also be seen)

Diagnostic Criteria

DSM5 calls it a major or mild neurocognitive disorder due to Huntington's disease. According to DSM 5: Criteria should meet for major or mild neurocognitive disorder. There is an insidious onset and gradual progression of symptoms. It should be clinically established as Huntington's disease, or risk of Huntington's disease should be present, which may be because of family history or genetic testing. It should not be attributable to another medical condition and not be better explained by another mental disorder.

Rule out other causes so we can say that the patient has dementia due to Huntington's disease.

Also read: Vascular Dementia: Causes, Diagnosis & Treatment

Laboratory Examination

MRI: When we do MRIs, caudate atrophy and striatal atrophy are seen. Family history plays a vital role in the diagnosis. So many times, there is a positive family history of Huntington's disease, and it is confirmed by genetic testing. We have a mutated gene, which is responsible for this, and genetic testing is usually done to make a diagnosis.

Course and Prognosis

It is progressive, and inevitably death may occur. It is fatal.

Treatment

As a psychiatrist, many times the symptoms of patients are to be managed. For symptomatic management.

• Chorea, predominantly seen in patients, gives dopamine-depleting agents. 
• Mood symptoms: antidepressants. 
• Agitation, psychosis and Antipsychotics

One should be careful when using antipsychotics because, many times, potent or first-generation antipsychotics increase some of the motor symptoms. So, one has to balance out the motor symptoms and the psychotic symptoms. Also, it has been seen that for cognitive impairment, cholinesterase inhibitors have not shown benefits for patients. So, we may not use cholinesterase inhibitors. Studies do not show good results now for Huntington's disease.

You may clinically see such patients, so you should have Huntington's disease as one of the differential diagnoses.

Also read: Frontotemporal Dementia: Symptoms, Genetics, and Prognosis

Important Points to Remember

• George Huntington first described Huntington's disease in 1872, and subsequently, it was named Huntington's disease.
• In 1993, the mutant gene responsible for Huntington's disease was identified.
• Family history plays a vital role in the diagnosis. So many times, there is a positive family history of Huntington's disease, and it is confirmed by genetic testing.
• One should be careful when using antipsychotics because, many times, potent or first-generation antipsychotics increase some of the motor symptoms. So, one has to balance out the motor symptoms and the psychotic symptoms.

Hope you found this blog helpful for your Psychiatry residency Neurology and General Medicine preparation. For more informative and interesting posts like these, keep reading PrepLadder’s blogs.

Download PrepLadder's best app for Psychiatry Residency preparation for Android 

Download PrepLadder's best app for Psychiatry Residency preparation for ios