Broca’s area, located in the inferior frontal gyrus of the dominant hemisphere, is a crucial region for language production. It controls the motor functions necessary for speech production, and damage to this area can result in difficulties forming words and speaking. While language comprehension remains intact, the individual may experience expressive dysphasia, struggling to produce speech.

Hardy-Weinberg Principle and Allele Frequency

Allele frequency refers to the proportion of a population that carries a specific variant at a particular gene locus. It can be calculated by dividing the number of individual alleles of a certain type by the total number of alleles in a population. The Hardy-Weinberg Principle states that both allele and genotype frequencies in a population remain constant from generation to generation unless specific disturbing influences are introduced. To remain in equilibrium, five conditions must be met, including no mutations, no gene flow, random mating, a sufficiently large population, and no natural selection. The Hardy-Weinberg Equation is used to predict the frequency of alleles in a population, and it can be used to estimate the carrier frequency of genetic diseases. For example, if the incidence of PKU is one in 10,000 babies, then the carrier frequency in the general population is 1/50. Couples with a previous child with PKU have a 25% chance of having another affected child.

Memory Forms

Memory is the ability to store, retain, and retrieve information. There are different forms of memory, including sensory memory, short-term/working memory, and long-term memory.

Sensory memory is the capacity for briefly retaining the large amounts of information that people encounter daily. It includes echoic memory (gathered through auditory stimuli), iconic memory (gathered through sight), and haptic memory (acquired through touch).

Short-term memory is the ability to keep a small amount of information available for a short period of time. Atkinson and Shiffrin’s multistore model (1968) suggests the existence of a short-term storehouse with limited capacity. Baddeley and Hitch (1974) further developed the concept of short-term memory, which eventually became known as Baddeley’s multi-storehouse model (2000). This model includes the central executive, visuospatial sketchpad, phonological buffer/loop, and episodic buffer.

Long-term memory includes declarative (of explicit) memories, which can be consciously retrieved, and nondeclarative (of implicit) memories, which cannot. Declarative memory includes episodic memory (stores personal experiences) and semantic memory (stores information about facts and concepts). Non-declarative memory includes procedural memory (recalls motor and executive skills), associative memory (storage and retrieval of information through association with other information), and non-associative memory (refers to newly learned behavior through repeated exposure to an isolated stimulus).

Overall, memory is a complex and essential cognitive function that plays a crucial role in learning, reasoning, and understanding.

The phenomenon known as placebo sag occurs when individuals who have undergone multiple treatment failures experience a decrease in the placebo effect. This is particularly common in chronically ill patients who may feel hopeless and discouraged. However, it is important to note that the extent to which the placebo effect diminishes over time varies depending on the individual’s experiences.

Understanding the Placebo Effect

In general, a placebo is an inert substance that has no pharmacological activity but looks, smells, and tastes like the active drug it is compared to. The placebo effect is the observable improvement seen when a patient takes a placebo, which results from patient-related factors such as expectations rather than the placebo itself. Negative effects due to patient-related factors are termed the nocebo effect.

Active placebos are treatments with chemical activity that mimic the side effects of the drug being tested in a clinical trial. They are used to prevent unblinding of the drug versus the placebo control group. Placebos need not always be pharmacological and can be procedural, such as sham electroconvulsive therapy.

The placebo effect is influenced by factors such as the perceived strength of the treatment, the status of the treating professional, and the branding of the compound. The placebo response is greater in mild illness, and the response rate is increasing over time. Placebo response is usually short-lived, and repeated use can lead to a diminished effect, known as placebo sag.

It is difficult to separate placebo effects from spontaneous remission, and patients who enter clinical trials generally do so when acutely unwell, making it challenging to show treatment effects. Breaking the blind may influence the outcome, and the expectancy effect may explain why active placebos are more effective than inert placebos. Overall, understanding the placebo effect is crucial in clinical trials and personalized medicine.

Ketamine, typically used in emergency medicine and paediatric anaesthesia, has been found to possess antidepressant properties and is currently being studied for its rapid onset efficacy. However, its acute side effect of inducing dissociation has raised concerns about its suitability for individuals with psychotic symptoms of emotionally unstable personality disorder.

Tauopathies exhibit tangles, but vascular dementia is not classified as one.

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.

Puberty

Puberty is a natural process that occurs in both boys and girls. The age range for the onset of puberty is between 8-14 years for females and 9-14 years for males, with the mean age of onset being 11 years for girls and 12 years for boys. The duration of puberty is typically 3-4 years. The onset of puberty is marked by the appearance of secondary sex characteristics, such as breast development in females and testicular enlargement in males. These characteristics evolve over time and are rated into 5 stages according to Tanner’s criteria. The sequence of events differs between boys and girls, with the onset of breast development (thelarche) generally preceding the onset of the first period (menarche) by around 2 years in girls. The pubertal growth spurt occurs during stages 3 to 4 in most boys and during stages 2 and 3 in girls. Precocious puberty, which occurs earlier than usual, is more common in girls than in boys. The age of onset of puberty in girls has been decreasing over time, with environmental factors such as nutrition potentially playing a role in this trend.

Most medical professionals recommend growth hormone therapy for girls diagnosed with Turner syndrome. Prenatal diagnosis can be achieved through chorionic villus sampling of amniocentesis, and while it has been traditionally believed that there is no increased risk in subsequent pregnancies, recent data suggests further studies are needed to confirm this.

Understanding Turner Syndrome

Turner syndrome is a genetic disorder that affects only females. It occurs when one of the two X chromosomes is missing of partially missing. This happens randomly and does not increase the risk of the condition in future siblings. Although X-inactivation occurs in females, having only one X chromosome can cause issues as not all genes are inactivated in the inactivated X chromosome.

The features of Turner syndrome include short stature, a webbed neck, a broad chest with widely spaced nipples, gonadal dysfunction leading to amenorrhea and infertility, congenital heart disease, and hypothyroidism. Despite these physical characteristics, girls with Turner syndrome typically have normal intelligence, with a mean full-scale IQ of 90. However, they may struggle with nonverbal, social, and psychomotor skills. It is important to understand the symptoms and effects of Turner syndrome to provide appropriate care and support for affected individuals.

Patients with existing ischaemic heart disease who experience depression have a relative risk of cardiac morbidity and mortality that ranges from 1.5 to 2.5.

Formal Thought Disorders

In formal thought disorders, changes in the speed, coherence, and cogency of thought can be observed from a patient’s speech. These disorders can also be self-reported and may be accompanied by enhanced use of nonverbal language. One possible indication is a lack of an adequate connection between two consecutive thoughts, which is called ‘asyndesis’.

There are several types of formal thought disorders, including inhibited thinking, retarded thinking, circumstantial thinking, restricted thinking, perseverative thinking, rumination, pressured thinking, flight of ideas, tangential thinking, thought blocking, disruption of thought, incoherence/derailment, and neologisms.

Inhibited thinking is about the subjective experience of the patient, who may feel that their thinking process is slowed down of blocked by an inner wall of resistance. Retarded thinking, on the other hand, is about the observed quality of thought as inferred through speech, where the flow of thought processes is slowed down and sluggish.

Circumstantial thinking refers to an inability to separate the essential from the unessential during a conversation without rendering the conversation incoherent. Restricted thinking involves a limited range of thought content, fixation on one particular topic of a small number of topics only, and a stereotyped pattern of thinking.

Perseverative thinking is characterized by the persistent repetition of previously used words, phrases, of details to the point where they become meaningless in the context of the current stage of the interview. Rumination is the endless mental preoccupation with, of excessive concern over, mostly unpleasant thoughts.

Pressured thinking, also known as crowding of thought, is when the patient feels helplessly exposed to the pressures of floods of different ideas of thoughts. Flight of ideas involves an increasing multitude of thoughts and ideas which are no longer firmly guided by clear goal-directed thinking.

Tangential thinking occurs when the patient appears to understand the contents of the questions addressed to them but provides answers which are completely out of context. Thought blocking of disruption of thought refers to sudden disruption of an otherwise normal flow of thought of speech for no obvious reason.

Incoherence of derailment is when the interviewer is unable to establish sensible connections between the patient’s thinking and verbal output, which is sometimes also called derailment. Neologisms involve the formation of new words of usage of words which disregard normal conventions and are generally not easily understandable.