ADHD (Diagnosis and Management in Children)

ADHD is a behavioural syndrome characterised by symptoms of inattention, hyperactivity, and impulsivity. The DSM-5 and ICD-11 provide diagnostic criteria for the condition, with both recognising three subtypes: predominantly inattentive, predominantly hyperactive-impulsive, and combined.

Treatment for children under 5 involves offering an ADHD-focused group parent-training programme as a first-line option. Medication should only be considered after obtaining advice from a specialist ADHD service. For children and young people aged 5-18, advice and support should be given, along with an ADHD-focused group parent-training programme. Medication should only be offered if ADHD symptoms persist after environmental modifications have been implemented and reviewed. Cognitive behavioural therapy may also be considered for those who have benefited from medication but still experience significant impairment.

NICE advises against elimination diets, dietary fatty acid supplementation, and the use of the ‘few foods diet’. Methylphenidate of lisdexamfetamine is the first-line medication option, with dexamphetamine considered for those who respond to lisdexamfetamine but cannot tolerate the longer effect profile. Atomoxetine of guanfacine may be offered for those who cannot tolerate methylphenidate of lisdexamfetamine. Clonidine and atypical antipsychotics should only be used with advice from a tertiary ADHD service.

Drug holidays may be considered for children and young people who have not met the expected height for their age due to medication. However, NICE advises that withdrawal from treatment is associated with a risk of symptom exacerbation.

The First Pass Effect in Psychiatric Drugs

The first-pass effect is a process in drug metabolism that significantly reduces the concentration of a drug before it reaches the systemic circulation. This phenomenon is related to the liver and gut wall, which absorb and metabolize the drug before it can enter the bloodstream. Psychiatric drugs are not exempt from this effect, and some undergo a significant reduction in concentration before reaching their target site. Examples of psychiatric drugs that undergo a significant first-pass effect include imipramine, fluphenazine, morphine, diazepam, and buprenorphine. On the other hand, some drugs undergo little to no first-pass effect, such as lithium and pregabalin.

Orally administered drugs are the most affected by the first-pass effect. However, there are other routes of administration that can avoid of partly avoid this effect. These include sublingual, rectal (partly avoids first pass), intravenous, intramuscular, transdermal, and inhalation. Understanding the first-pass effect is crucial in drug development and administration, especially in psychiatric drugs, where the concentration of the drug can significantly affect its efficacy and safety.

Psychogenic polydipsia is a condition where there is excessive consumption of fluids leading to polyuria, and it is commonly seen in psychiatric conditions such as schizophrenia and developmental disorders. The exact mechanism is unknown, but it is thought to be due to a defect in thirst and a dysfunction in AVP regulation. Patients with psychogenic polydipsia rarely complain of thirst but instead provide delusional explanations for their excessive drinking of state that drinking reduces their anxiety and makes them feel better. If fluid intake exceeds the capacity for excretion, then the resultant hyponatremia may produce signs of water intoxication. It is best managed by fluid restriction. Differential diagnosis should be done to rule out other causes of polyuria and polydipsia. Investigations such as fluid balance charts, urine dipstick, serum U&E and calcium, and urine and plasma osmolality should be arranged. Primary polydipsia can be subclassified into psychogenic and dipsogenic types.

Intermediate Mechanism: Rationalisation

Rationalisation is a defense mechanism commonly used by individuals to create false but credible justifications for their behavior of actions. It involves the use of logical reasoning to explain away of justify unacceptable behavior of feelings. The individual may not be aware that they are using this mechanism, and it can be difficult to identify in oneself.

Rationalisation is considered an intermediate mechanism, as it is common in healthy individuals from ages three to ninety, as well as in neurotic disorders and in mastering acute adult stress. It can be dramatically changed by conventional psychotherapeutic interpretation.

Examples of rationalisation include a student who fails an exam and blames the teacher for not teaching the material well enough, of a person who cheats on their partner and justifies it by saying their partner was neglectful of unaffectionate. It allows the individual to avoid taking responsibility for their actions and to maintain a positive self-image.

Overall, rationalisation can be a useful defense mechanism in certain situations, but it can also be harmful if it leads to a lack of accountability and an inability to learn from mistakes.

Heterogeneity is characterized by the existence of multiple genetic abnormalities that result in the same disorder.

Understanding Penetrance in Genetic Diseases

Penetrance refers to the likelihood of individuals with a specific genetic mutation developing clinical symptoms of a disease. It is expressed as a percentage, indicating the proportion of individuals with the mutation who exhibit symptoms. For instance, if a mutation in a gene responsible for an autosomal dominant disorder has a penetrance of 90%, it means that 90% of individuals with the mutation will develop the disease, while the remaining 10% will not.

Penetrance is an essential concept in genetics, as it helps to predict the likelihood of a disease occurring in individuals with a specific genetic mutation. However, it is important to note that penetrance can vary depending on several factors, including age, gender, and environmental factors. Therefore, it is crucial to consider these factors when assessing the risk of developing a genetic disease. Understanding penetrance can also aid in genetic counseling and the development of personalized treatment plans for individuals with genetic mutations.

Hyperkinesia is a defining feature of tics.

Movement Disorders: Key Features

Movement disorders refer to a range of conditions that affect voluntary muscle movements. These disorders can be caused by various factors, including neurological conditions, medication side effects, and metabolic imbalances. The following table outlines some of the key features of common movement disorders:

Akinesia: Absence of loss of control of voluntary muscle movements, often seen in severe Parkinson’s disease.

Bradykinesia: Slowness of voluntary movement, a core symptom of Parkinson’s disease.

Akathisia: Subjective feeling of inner restlessness, often caused by antipsychotic medication use.

Athetosis: Continuous stream of slow, flowing, writhing involuntary movements, often seen in cerebral palsy, stroke, and Huntington’s disease.

Chorea: Brief, quasi-purposeful, irregular contractions that appear to flow from one muscle to the next, often seen in Huntington’s disease and Wilson’s disease.

Dystonia: Involuntary sustained of intermittent muscle contractions that cause twisting and repetitive movements, abnormal postures, of both.

Dyskinesia: General term referring to problems with voluntary movements and the presence of involuntary movements, often drug-induced.

Myoclonus: A sequence of repeated, often non-rhythmic, brief shock-like jerks due to sudden involuntary contraction of relaxation of one of more muscles.

Parkinsonism: Syndrome characterized by tremor, rigidity, and bradykinesia.

Tic: Sudden, repetitive, non-rhythmic, stereotyped motor movement of vocalization involving discrete muscle groups, often seen in Tourette’s syndrome.

Tremor: Involuntary, rhythmic, alternating movement of one of more body parts, often seen in essential tremor, Parkinson’s disease, and alcohol withdrawal.

Hemiballismus: Repetitive, but constantly varying, large amplitude involuntary movements of the proximal parts of the limbs, often seen in stroke and traumatic brain injury.

Stereotypies: Repetitive, simple movements that can be voluntarily suppressed, often seen in autism and intellectual disability.

It is important to consider the underlying conditions and factors that may contribute to movement disorders in order to properly diagnose and treat these conditions.

Cold and Menthol receptor 1 (CMR1) is a protein that in humans is encoded by TRPM8 gene. It is primarily responsible for the detection of temperatures ranging from 8-28 C. It is an ion channel which upon activation causes the influx of Na+ and Ca+ ions into the cell that leads to the depolarization and generation of an action potential.

The prevalence of the disease is 20% as there are currently 200 cases out of a total population of 1000.

Apart from Bleuler who is Swiss, all the other psychiatrists in the list of options are German – Kraepelin and…

Antipsychiatry is a movement that emerged in the 1960s and challenges the traditional medical model of mental illness. It argues that mental illnesses are not biological of medical conditions but rather social constructs that reflect deviations from social norms. The movement has been associated with several famous figures, including Thomas Szasz, R.D. Laing, Michel Foucault, and Franco Basaglia. These individuals have criticized the psychiatric profession for its use of involuntary hospitalization, medication, and other forms of coercion in the treatment of mental illness. They have also advocated for alternative approaches to mental health care, such as community-based care and psychotherapy. Despite its controversial nature, the antipsychiatry movement has had a significant impact on the field of mental health and continues to influence the way we think about and treat mental illness today.

The caffeine content in brewed coffee is relatively high, with approximately 100 mg per cup. In comparison, tea has a lower caffeine content. Black tea has around 45 mg per cup, while green tea has approximately 25 mg per cup. Instant coffee contains about 60 mg per cup, and a can of Red Bull contains 80 mg of caffeine.

The Bazett formula adjusts the QT interval for heart rate by taking the square root of the R-R interval and dividing the QT interval by it.

QTc Prolongation: Risks and Identification

The QT interval is a measure of the time it takes for the ventricles to repolarize and is calculated from the beginning of the QRS complex to the end of the T wave. However, the QT interval varies with the heart rate, making it difficult to use a single number as a cut-off for a prolonged QT. Instead, a corrected QT interval (QTc) is calculated for each heart rate using various formulas. A QTc over the 99th percentile is considered abnormally prolonged, with approximate values of 470 ms for males and 480 ms for females.

Prolonged QT intervals can lead to torsade de pointes (TdP), a polymorphic ventricular tachycardia that can be fatal if it degenerates into ventricular fibrillation. TdP is characterized by a twisting of the QRS complexes around an isoelectric line and is often asymptomatic but can also be associated with syncope and death. An accurate diagnosis requires an ECG to be recorded during the event. It is important to note that an increase in the QT interval due to a new conduction block should not be considered indicative of acquired LQTS and risk for TdP.

Eating disorders are serious mental health conditions that can have severe physical consequences. Anorexia nervosa is diagnosed when a person has a BMI less than 17.5 kg/m2, self-induced weight loss, body image distortion, and abnormalities of the hypothalamic-pituitary-gonadal axis. On the other hand, bulimia nervosa is diagnosed when a person experiences recurrent episodes of binge eating and recurrent inappropriate compensatory behavior to prevent weight gain, occurring more than twice weekly for three months. Unlike anorexia nervosa, there is no diagnostic requirement for weight loss in bulimia nervosa. Both conditions are characterized by a preoccupation with shape and weight, and obtaining a reliable dietary history from the patient is unlikely. A key feature of bulimia nervosa is a feeling of loss of control during binge eating episodes.

Amantadine and QTc Prolongation

Amantadine is a medication used to treat Parkinson’s disease and influenza. It has been associated with QTc prolongation, which can increase the risk of Torsades de points. Therefore, caution should be exercised when prescribing amantadine to patients with risk factors for QT prolongation. If a patient is already taking amantadine and develops a prolonged QTc interval, the medication should be discontinued and an alternative treatment considered. It is important to monitor the QTc interval in patients taking amantadine, especially those with risk factors for QT prolongation.

The Basal Ganglia: Functions and Disorders

The basal ganglia are a group of subcortical structures that play a crucial role in controlling movement and some cognitive processes. The components of the basal ganglia include the striatum (caudate, putamen, nucleus accumbens), subthalamic nucleus, globus pallidus, and substantia nigra (divided into pars compacta and pars reticulata). The putamen and globus pallidus are collectively referred to as the lenticular nucleus.

The basal ganglia are connected in a complex loop, with the cortex projecting to the striatum, the striatum to the internal segment of the globus pallidus, the internal segment of the globus pallidus to the thalamus, and the thalamus back to the cortex. This loop is responsible for regulating movement and cognitive processes.

However, problems with the basal ganglia can lead to several conditions. Huntington’s chorea is caused by degeneration of the caudate nucleus, while Wilson’s disease is characterized by copper deposition in the basal ganglia. Parkinson’s disease is associated with degeneration of the substantia nigra, and hemiballism results from damage to the subthalamic nucleus.

In summary, the basal ganglia are a crucial part of the brain that regulate movement and some cognitive processes. Disorders of the basal ganglia can lead to significant neurological conditions that affect movement and other functions.

The projective approach to personality assessment utilizes ambiguous test stimuli to reveal information about an individual’s personality. The Rorschach test, which involves ten inkblot cards, is the most widely used and researched projective test. The Thematic Apperception Test (TAT) is another projective measure that uses 20 stimulus cards depicting ambiguous scenes. The Make a Picture Story (MAPS) test is similar to the TAT but allows the patient to manage the stimuli. In contrast, the Minnesota Multiphasic Personality Inventory (MMPI) and the Personality Assessment Inventory (PAI) are objective measures of personality in adults.

Acetaldehyde dehydrogenase is irreversibly bound by disulfiram.

Mechanisms of Action of Different Drugs

Understanding the mechanisms of action of different drugs is crucial for medical professionals. It is a common topic in exams and can earn easy marks if studied well. This article provides a list of drugs and their mechanisms of action in different categories such as antidepressants, anti dementia drugs, mood stabilizers, anxiolytic/hypnotic drugs, antipsychotics, drugs of abuse, and other drugs. For example, mirtazapine is a noradrenaline and serotonin specific antidepressant that works as a 5HT2 antagonist, 5HT3 antagonist, H1 antagonist, alpha 1 and alpha 2 antagonist, and moderate muscarinic antagonist. Similarly, donepezil is a reversible acetylcholinesterase inhibitor used as an anti dementia drug, while valproate is a GABA agonist and NMDA antagonist used as a mood stabilizer. The article also explains the mechanisms of action of drugs such as ketamine, phencyclidine, buprenorphine, naloxone, atomoxetine, varenicline, disulfiram, acamprosate, and sildenafil.

Antipsychotics can be classified in various ways, including by chemical structure. One common classification is into typical (first generation) and atypical (second generation) antipsychotics. Haloperidol is a butyrophenone, while other antipsychotics fall into categories such as benzoxazoles (risperidone), dibenzodiazapines (clozapine), dibenzothiazapines (quetiapine), and Thienobenzodiazepine (olanzapine). Phenothiazines are another structural classification, with three groups: aliphatic compounds (chlorpromazine, promazine, methotrimeprazine), piperazines (trifluoperazine, fluphenazine, perphenazine), and piperidines (thioridazine, pipothiazine). Other structural categories include thioxanthenes (flupentixol, zuclopenthixol), diphenylbutylpiperidine (pimozide), substituted benzamides (sulpiride, amisulpride), and arylpiperidylindole (quinolone) such as aripiprazole.

Mutations are changes in the DNA of a cell. There are different types of mutations, including missense mutations, nonsense mutations, point mutations, frameshift mutations, and silent mutations. Missense mutations alter the codon, resulting in a different amino acid in the protein product. Nonsense mutations change a codon that specifies an amino acid to a stop codon, which prematurely stops the translation process. Point mutations involve a single change in one base of the gene sequence. Frameshift mutations occur when a number of nucleotides are inserted of deleted, causing a shift in the sequence and a different translation than the original. Silent mutations code for the same amino acid. Stop codons are nucleotide triplets that signal the end of the translation process. There are three types of stop codons: TAA, TAG, and TGA. When these codons undergo DNA transcription, they change to UAA, UAG, and UGA, which are the stop codons found in RNA molecules.

Perseveration: The Clinical Symptoms in Chronic Schizophrenia and Organic Dementia

Perseveration is a common behavior observed in patients with organic brain involvement. It is characterized by the conscious continuation of an act of an idea. This behavior is frequently seen in patients with delirium, epilepsy, dementia, schizophrenia, and normal individuals under extreme fatigue of drug-induced states.

In chronic schizophrenia and organic dementia, perseveration is a prominent symptom. Patients with these conditions tend to repeat the same words, phrases, of actions over and over again, even when it is no longer appropriate of relevant to the situation. This behavior can be frustrating for caregivers and family members, and it can also interfere with the patient’s ability to communicate effectively.

In schizophrenia, perseveration is often associated with disorganized thinking and speech. Patients may jump from one topic to another without any logical connection, and they may repeat the same words of phrases in an attempt to express their thoughts. In organic dementia, perseveration is a sign of cognitive decline and memory impairment. Patients may repeat the same stories of questions, forgetting that they have already asked of answered them.

Overall, perseveration is a common symptom in patients with organic brain involvement, and it can have a significant impact on their daily functioning and quality of life. Understanding this behavior is essential for effective management and treatment of these conditions.

The Geriatric Mental State Schedule (GMSS) is a tool utilized to detect signs of depression among older adults.

In psychiatry, various questionnaires and interviews are used to assess different conditions and areas. It is important for candidates to know whether certain assessment tools are self-rated of require clinical assistance. The table provided by the college lists some of the commonly used assessment tools and indicates whether they are self-rated of clinician-rated. For example, the HAMD and MADRS are clinician-rated scales used to assess the severity of depression, while the GDS is a self-rated scale used to screen for depression in the elderly. The YMRS is a clinician-rated scale used to assess the severity of mania in patients with bipolar disorder, while the Y-BOCS is used to measure both the severity of OCD and the response to treatment. The GAF provides a single measure of global functioning, while the CGI requires the clinician to rate the severity of the patient’s illness at the time of assessment. The CAMDEX is a tool developed to assist in the early diagnosis and measurement of dementia in the elderly.

Rett syndrome is caused by mutations in the MeCP2 gene.

Tuberous Sclerosis: A Neurocutaneous Syndrome with Psychiatric Comorbidity

Tuberous sclerosis is a genetic disorder that affects multiple organs, including the brain, and is associated with significant psychiatric comorbidity. This neurocutaneous syndrome is inherited in an autosomal dominant pattern with a high penetrance rate of 95%, but its expression can vary widely. The hallmark of this disorder is the growth of multiple non-cancerous tumors in vital organs, including the brain. These tumors result from mutations in one of two tumor suppressor genes, TSC1 and TSC2. The psychiatric comorbidities associated with tuberous sclerosis include autism, ADHD, depression, anxiety, and even psychosis.

Agomelatine (Valdoxan) is a novel antidepressant that functions as an agonist at both MT1 and MT2 receptors, while also acting as a 5HT2C antagonist. Unlike most other antidepressants, it does not affect monoamine uptake.
First-generation antipsychotics work by antagonizing D2 receptors.
Benzodiazepines exert their effects by potentiating GABA.
Noradrenaline reuptake inhibition is a common mechanism of action for many antidepressants, including SNRIs and tricyclics.
SSRI (and other) antidepressants function by inhibiting the reuptake of serotonin.

The Positive and Negative Syndrome Scale (PANSS) is a tool used to measure the severity of symptoms in patients with schizophrenia. The scale is divided into three categories: positive symptoms, negative symptoms, and general psychopathology symptoms. Each category has several items that are scored on a seven-point severity scale. The positive symptoms include delusions, hallucinations, and hyperactivity, while the negative symptoms include blunted affect and lack of spontaneity. The general psychopathology symptoms include anxiety, depression, and poor impulse control. The PANSS is a valuable tool for clinicians to assess the severity of symptoms in patients with schizophrenia and to monitor their progress over time.

The defence mechanism of altruism is considered to be a sign of emotional maturity, as it involves channeling one’s own psychological distress towards aiding others.

Autism: A Brief History

The term autism was first coined in 1911 by Eugen Bleuler to describe individuals with schizophrenia who had cut themselves off as much as possible from any contact with the external world. In 1926, Grunya Sukhareva attempted to delineate autism spectrum disorders as distinct diagnostic entities, referring to them as schizoid personality disorder. However, her work remained largely unknown until 1996.

The first widely publicized use of the term autism to describe a distinct condition was in 1943 by Leo Kanner, who referred to it as autistic disturbance of affective contact. Kanner suggested that autism may be a manifestation of childhood schizophrenia and that it was characterized by an inability to related to themselves in the ordinary way to people and situations from the beginning of life. In 1944, Hans Asperger published descriptions of four cases of a condition he termed der autistichen psychopathie, which he regarded as a limitation of social relationships.

In 1980, infantile autism was included in the DSM-III under a new category of pervasive developmental disorders. Lorna Wing redefined Asperger Syndrome in 1981, proposing a triad of impairments in social interaction, communication, and imaginative activities. In 2000, the DSM-IV utilized the umbrella category of pervasive developmental disorders, with five main subcategories. Finally, in 2013, the DSM-5 combined the subcategories into a single label of autism spectrum disorder, asserting that autism is a single disorder on a wide spectrum.

It is important to note that there is no collateral history available and the duration of the observed behaviour pattern is unknown. Additionally, the individual’s excessive panting and pacing may indicate motor over-activity, which is consistent with symptoms of mania. Therefore, it is necessary to consider the possibility of a drug-induced state as a potential differential diagnosis. However, until further information is obtained, it is crucial to treat this as an episode of mania.

Genetic Conditions and Their Features

Genetic conditions are disorders caused by abnormalities in an individual’s DNA. These conditions can affect various aspects of a person’s health, including physical and intellectual development. Some of the most common genetic conditions and their features are:

– Downs (trisomy 21): Short stature, almond-shaped eyes, low muscle tone, and intellectual disability.
– Angelman syndrome (Happy puppet syndrome): Flapping hand movements, ataxia, severe learning disability, seizures, and sleep problems.
– Prader-Willi: Hyperphagia, excessive weight gain, short stature, and mild learning disability.
– Cri du chat: Characteristic cry, hypotonia, down-turned mouth, and microcephaly.
– Velocardiofacial syndrome (DiGeorge syndrome): Cleft palate, cardiac problems, and learning disabilities.
– Edwards syndrome (trisomy 18): Severe intellectual disability, kidney malformations, and physical abnormalities.
– Lesch-Nyhan syndrome: Self-mutilation, dystonia, and writhing movements.
– Smith-Magenis syndrome: Pronounced self-injurious behavior, self-hugging, and a hoarse voice.
– Fragile X: Elongated face, large ears, hand flapping, and shyness.
– Wolf Hirschhorn syndrome: Mild to severe intellectual disability, seizures, and physical abnormalities.
– Patau syndrome (trisomy 13): Severe intellectual disability, congenital heart malformations, and physical abnormalities.
– Rett syndrome: Regression and loss of skills, hand-wringing movements, and profound learning disability.
– Tuberous sclerosis: Hamartomatous tumors, epilepsy, and behavioral issues.
– Williams syndrome: Elfin-like features, social disinhibition, and advanced verbal skills.
– Rubinstein-Taybi syndrome: Short stature, friendly disposition, and moderate learning disability.
– Klinefelter syndrome: Extra X chromosome, low testosterone, and speech and language issues.
– Jakob’s syndrome: Extra Y chromosome, tall stature, and lower mean intelligence.
– Coffin-Lowry syndrome: Short stature, slanting eyes, and severe learning difficulty.
– Turner syndrome: Short stature, webbed neck, and absent periods.
– Niemann Pick disease (types A and B): Abdominal swelling, cherry red spot, and feeding difficulties.

It is important to note that these features may vary widely among individuals with the same genetic condition. Early diagnosis and intervention can help individuals with genetic conditions reach their full potential and improve their quality of life.

Genomics: Understanding DNA, RNA, Transcription, and Translation

Deoxyribonucleic acid (DNA) is a molecule composed of two chains that coil around each other to form a double helix. DNA is organised into chromosomes, and each chromosome is made up of DNA coiled around proteins called histones. RNA, on the other hand, is made from a long chain of nucleotide units and is usually single-stranded. RNA is transcribed from DNA by enzymes called RNA polymerases and is central to protein synthesis.

Transcription is the synthesis of RNA from a DNA template, and it consists of three main steps: initiation, elongation, and termination. RNA polymerase binds at a sequence of DNA called the promoter, and the transcriptome is the collection of RNA molecules that results from transcription. Translation, on the other hand, refers to the synthesis of polypeptides (proteins) from mRNA. Translation takes place on ribosomes in the cell cytoplasm, where mRNA is read and translated into the string of amino acid chains that make up the synthesized protein.

The process of translation involves messenger RNA (mRNA), transfer RNA (tRNA), and ribosomal RNA (rRNA). Transfer RNAs, of tRNAs, connect mRNA codons to the amino acids they encode, while ribosomes are the structures where polypeptides (proteins) are built. Like transcription, translation also consists of three stages: initiation, elongation, and termination. In initiation, the ribosome assembles around the mRNA to be read and the first tRNA carrying the amino acid methionine. In elongation, the amino acid chain gets longer, and in termination, the finished polypeptide chain is released.

Huntington’s Disease: Genetics and Pathology

Huntington’s disease is a genetic disorder that follows an autosomal dominant pattern of inheritance. It is caused by a mutation in the Huntington gene, which is located on chromosome 4. The mutation involves an abnormal expansion of a trinucleotide repeat sequence (CAG), which leads to the production of a toxic protein that damages brain cells.

The severity of the disease and the age of onset are related to the number of CAG repeats. Normally, the CAG sequence is repeated less than 27 times, but in Huntington’s disease, it is repeated many more times. The disease shows anticipation, meaning that it tends to worsen with each successive generation.

The symptoms of Huntington’s disease typically begin in the third of fourth decade of life, but in rare cases, they can appear in childhood of adolescence. The most common symptoms include involuntary movements (chorea), cognitive decline, and psychiatric disturbances.

The pathological hallmark of Huntington’s disease is the gross bilateral atrophy of the head of the caudate and putamen, which are regions of the brain involved in movement control. The EEG of patients with Huntington’s disease shows a flattened trace, indicating a loss of brain activity.

Macroscopic pathological findings include frontal atrophy, marked atrophy of the caudate and putamen, and enlarged ventricles. Microscopic findings include neuronal loss and gliosis in the cortex, neuronal loss in the striatum, and the presence of inclusion bodies in the neurons of the cortex and striatum.

In conclusion, Huntington’s disease is a devastating genetic disorder that affects the brain and causes a range of motor, cognitive, and psychiatric symptoms. The disease is caused by a mutation in the Huntington gene, which leads to the production of a toxic protein that damages brain cells. The pathological changes in the brain include atrophy of the caudate and putamen, neuronal loss, and the presence of inclusion bodies.

Alzheimer’s disease is characterized by both macroscopic and microscopic changes in the brain. Macroscopic changes include cortical atrophy, ventricular dilation, and depigmentation of the locus coeruleus. Microscopic changes include the presence of senile plaques, neurofibrillary tangles, gliosis, degeneration of the nucleus of Meynert, and Hirano bodies. Senile plaques are extracellular deposits of beta amyloid in the gray matter of the brain, while neurofibrillary tangles are intracellular inclusion bodies that consist primarily of hyperphosphorylated tau. Gliosis is marked by increases in activated microglia and reactive astrocytes near the sites of amyloid plaques. The nucleus of Meynert degenerates in Alzheimer’s, resulting in a decrease in acetylcholine in the brain. Hirano bodies are actin-rich, eosinophilic intracytoplasmic inclusions which have a highly characteristic crystalloid fine structure and are regarded as a nonspecific manifestation of neuronal degeneration. These changes in the brain contribute to the cognitive decline and memory loss seen in Alzheimer’s disease.