The WAIS-III provides results for verbal IQ, performance IQ, and full scale IQ, which are compared to the average scores of the population. The average IQ for adults is 100, with a standard deviation of 15 points. However, the Wisconsin card sorting test, which is used to evaluate frontal lobe impairment, is not included in the WAIS-III.

NMS can be identified by three primary symptoms: hyperthermia, rigidity, and elevated creatine phosphokinase concentration. If these symptoms are not present, the diagnosis of NMS should be reconsidered as other symptoms may be present in patients taking neuroleptics without having NMS. This information was reported by P Adnet in the British Journal of Anaesthesia in 2000.

Serotonin Syndrome and Neuroleptic Malignant Syndrome are two conditions that can be difficult to differentiate. Serotonin Syndrome is caused by excess serotonergic activity in the CNS and is characterized by neuromuscular abnormalities, altered mental state, and autonomic dysfunction. On the other hand, Neuroleptic Malignant Syndrome is a rare acute disorder of thermoregulation and neuromotor control that is almost exclusively caused by antipsychotics. The symptoms of both syndromes can overlap, but there are some distinguishing clinical features. Hyper-reflexia, ocular clonus, and tremors are more prominent in Serotonin Syndrome, while Neuroleptic Malignant Syndrome is characterized by uniform ‘lead-pipe’ rigidity and hyporeflexia. Symptoms of Serotonin Syndrome usually resolve within a few days of stopping the medication, while Neuroleptic Malignant Syndrome can take up to 14 days to remit with appropriate treatment. The following table provides a useful guide to the main differentials of Serotonin Syndrome and Neuroleptic Malignant Syndrome.

Umami taste or savoury taste is one of the five basic tastes described as meaty or brothy. The basic taste “umami” is mediated by glutamate acting on a metabotropic receptor named mGluR4 (metabotropic glutamate receptor 4). Additionally, umami taste is also mediated by the T1R1/T1R3 heterodimer, which is a combination of two G protein-coupled receptors. These receptors are responsible for detecting the presence of glutamate and other amino acids, contributing to the savory flavor characteristic of umami.

All serotonin receptors, except for 5-HT3, are coupled with G proteins instead of being ligand gated ion channels.

Serotonin (5-hydroxytryptamine, 5-HT) receptors are primarily G protein receptors, except for 5-HT3, which is a ligand-gated receptor. It is important to remember that 5-HT3 is most commonly associated with nausea. Additionally, 5-HT7 is linked to circadian rhythms. The stimulation of 5-HT2 receptors is believed to be responsible for the side effects of insomnia, agitation, and sexual dysfunction that are associated with the use of selective serotonin reuptake inhibitors (SSRIs).

Understanding Wilson’s Disease: Causes, Symptoms, and Management

Wilson’s disease, also known as hepatolenticular degeneration, is a genetic disorder that affects copper storage in the body. This condition is caused by a defect in the ATP7B gene, which leads to the accumulation of copper in the liver and brain. The onset of symptoms usually occurs between the ages of 10 and 25, with liver disease being the most common presentation in children and neurological symptoms in young adults.

The excessive deposition of copper in the tissues can cause a range of symptoms, including hepatitis, cirrhosis, basal ganglia degeneration, speech and behavioral problems, asterixis, chorea, dementia, Kayser-Fleischer rings, sunflower cataract, renal tubular acidosis, haemolysis, and blue nails. Diagnosis is based on reduced serum ceruloplasmin, reduced serum copper, and increased 24-hour urinary copper excretion.

The traditional first-line treatment for Wilson’s disease is penicillamine, which chelates copper. Trientine hydrochloride is an alternative chelating agent that may become first-line treatment in the future. Tetrathiomolybdate is a newer agent that is currently under investigation.

In summary, Wilson’s disease is a genetic disorder that affects copper storage in the body, leading to a range of symptoms that can affect the liver, brain, and eyes. Early diagnosis and treatment are essential to prevent complications and improve outcomes.

– Functional hallucination requires an external stimulus to provoke the hallucination
– The normal perception and hallucination are in the same modality
– Example: sound of the boiler triggers auditory hallucinations
– Extracampine hallucinations occur outside of one’s sensory field
– Reflex hallucination is when a stimulus in one modality produces hallucination in another
– Reflex hallucination is a form of synaesthesia
– Third person auditory hallucination is when a person hears voices talking about them as a third person.

The Dunning-Kruger effect refers to a phenomenon where individuals with limited skills of knowledge tend to overestimate their abilities, leading them to believe they are more competent than they actually are.

The Flynn Effect is the term used to describe the increase in standardised intelligence test scores over time. Research conducted by Flynn showed that IQ scores increased by 13.8 points between 1932 and 1978, which equates to a 0.3-point increase per year of approximately 3 points per decade. More recent studies have also supported the Flynn effect, with IQ score gains observed between 1972 and 2006. This means that an individual is likely to achieve a higher IQ score on an earlier version of a test than on the current version. In fact, the test will overestimate an individual’s IQ score by an average of 0.3 points per year between the year in which the test was normed and the year in which the test was administered.

Most antidepressants and stimulants target monoamine transporters, which are crucial molecular targets. These transporters are also targeted by 30% of all psychotropic drugs. Another 30% of psychotropic drugs target G-protein-linked receptors, while enzymes are targeted by about 10% of these drugs. Monoamine oxidase inhibitors (MAOIs) are a type of antidepressant that targets the enzyme monoamine oxidase. Ligand-gated and voltage-gated ion channels are targeted by 20% and 10% of all psychotropic drugs, respectively.

Teleology, derived from the Greek words for goal and theory, is a moral philosophy that emphasizes the outcomes of actions as the initial consideration in evaluating ethical behavior. This category of theories is also known as consequentialism, as it focuses on the consequences of an action as the basis for determining its morality. Consequentialism evaluates the morality of an action based on the balance of its positive and negative outcomes. Utilitarianism of social consequentialism is the most prevalent form of consequentialism, although it is not the only one.

Ethical theory and principles are important in medical ethics. There are three key ethical theories that have dominated medical ethics: utilitarianism, deontological, and virtue-based. Utilitarianism is based on the greatest good for the greatest number and is a consequentialist theory. Deontological ethics emphasize moral duties and rules, rather than consequences. Virtue ethics is based on the ethical characteristics of a person and is associated with the concept of a good, happy, flourishing life.

More recent frameworks have attempted to reconcile different theories and values. The ‘four principles’ of ‘principlism’ approach, developed in the United States, is based on four common, basic prima facie moral commitments: autonomy, beneficence, non-maleficence, and justice. Autonomy refers to a patient’s right to make their own decisions, beneficence refers to the expectation that a doctor will act in a way that will be helpful to the patient, non-maleficence refers to the fact that doctors should avoid harming their patients, and justice refers to the expectation that all people should be treated fairly and equally.

Projection is classified as an underdeveloped defense mechanism, as it is considered immature. Freud proposed the idea that defenses evolve along a spectrum of personality growth. As an illustration, as time passes and the connections between the frontal lobe and the limbic system continue to myelinate, the defense mechanism commonly seen in adolescence, acting out (such as impulsive and momentarily soothing outbursts), may give rise to reaction formation and potentially even altruism in the future.

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.

Courtesy stigma, also known as stigma by association, is a genuine type of stigma that targets individuals who are connected to those with mental health issues, such as family members and healthcare providers. The remaining terms are not valid.

Stigma is a term used to describe the negative attitudes and beliefs that people hold towards individuals who are different from them. There are several types of stigma, including discredited and discreditable stigma, felt stigma, enacted stigma, and courtesy stigma. Discredited stigma refers to visible stigmas such as race, gender, of physical disability, while discreditable stigma refers to concealable stigmas such as mental illness of HIV infection. Felt stigma is the shame and fear of discrimination that prevents people from seeking help, while enacted stigma is the experience of unfair treatment by others. Finally, courtesy stigma refers to the stigma that attaches to those who are associated with a stigmatized person.

– Catatonia is a psychiatric syndrome characterized by disturbed motor functions, mood, and thought.
– Key behaviors associated with catatonia include stupor, posturing, waxy flexibility, negativism, automatic obedience, mitmachen, mitgehen, ambitendency, psychological pillow, forced grasping, obstruction, echopraxia, aversion, mannerisms, stereotypies, motor perseveration, echolalia, and logorrhoea.
– These behaviors are often tested in exam questions.
– Karl Ludwig Kahlbaum is credited with the original clinical description of catatonia.

Vigabatrin is known to cause visual field constriction in approximately 30% of its users. Although the majority of cases are asymptomatic, as the drug primarily affects peripheral fields and not central visual acuity, the effects are typically irreversible of only partially reversible after discontinuation of the medication. Patients who are over the age of 10 and are prescribed vigabatrin should undergo baseline threshold visual field testing and follow-up every six months. It is important for patients to report any new vision problems, such as blurring, double vision, of signs of peripheral vision impairment. Vigabatrin is only recommended for specialist use and is indicated for epilepsy that is not adequately controlled by other medications.

Recent clinical trials have shown that various psychotherapy approaches do not differ significantly in terms of effectiveness. This particular trial aimed to prove that psychodynamic psychotherapy was not inferior to other modalities at 22 weeks and one year follow-up. While non-inferiority was observed at 22 weeks, it could not be conclusively demonstrated at one year, despite no significant difference between interventions. Interestingly, individuals who received CBT appeared to require more additional treatment during the year following therapy, although this trend was not statistically significant.

Tamoxifen metabolism to its active metabolite may be inhibited by the use of fluoxetine and paroxetine, therefore, these medications should be avoided in patients receiving tamoxifen. Venlafaxine is considered the safest choice of antidepressant as it has little to no effect on tamoxifen metabolism. Mirtazapine has been found to have minimal effect on CYP2D6, while the other commonly prescribed antidepressants have mild to moderate degrees of CYP2D6 inhibition.

The two sample unpaired t test is utilized to examine whether the null hypothesis that the two populations related to the two random samples are equivalent is true of not. When dealing with continuous data that is believed to conform to the normal distribution, a t test is suitable, making it appropriate for comparing weight loss between two groups. In contrast, a paired t test is used when the data is dependent, meaning there is a direct correlation between the values in the two samples. This could include the same subject being measured before and after a process change of at different times.

According to a recent study by Ran (2019), lithium carbonate has been found to have a neuroprotective effect in individuals who have experienced a stroke. The study conducted exploratory analyses of neuroanatomical and cognitive outcomes in a poststroke population. It is interesting to note that while lithium is contraindicated in individuals with Addison’s disease, it is only cautioned in individuals with QT prolongation. Hypothyroidism (untreated) is also a contraindication for lithium. Addison’s disease is a condition characterized by inadequate production of cortisol and aldosterone by the adrenal cortex, leading to symptoms such as fatigue, gastrointestinal abnormalities, changes in skin pigmentation, and mood changes. In some cases, acute adrenal failure can occur, which is a serious condition that develops rapidly. The cause of Addison’s disease is often due to the body’s immune system mistakenly attacking the adrenal glands, causing progressive damage to the adrenal cortex.

Lithium – Pharmacology

Pharmacokinetics:
Lithium salts are rapidly absorbed following oral administration and are almost exclusively excreted by the kidneys unchanged. Blood samples for lithium should be taken 12 hours post-dose.

Ebstein’s:
Ebstein’s anomaly is a congenital malformation consisting of a prolapse of the tricuspid valve into the right ventricle. It occurs in 1:20,000 of the general population. Initial data suggested it was more common in those using lithium but this had not held to be true.

Contraindications:
Addison’s disease, Brugada syndrome, cardiac disease associated with rhythm disorders, clinically significant renal impairment, untreated of untreatable hypothyroidism, low sodium levels.

Side-effects:
Common side effects include nausea, tremor, polyuria/polydipsia, rash/dermatitis, blurred vision, dizziness, decreased appetite, drowsiness, metallic taste, and diarrhea. Side-effects are often dose-related.

Long-term use is associated with hypothyroidism, hyperthyroidism, hypercalcemia/hyperparathyroidism, irreversible nephrogenic diabetes insipidus, and reduced GFR.

Lithium-induced diabetes insipidus:
Treatment options include stopping lithium (if feasible), keeping levels within 0.4-0.8 mmol/L, once-daily dose of the drug taken at bedtime, amiloride, thiazide diuretics, indomethacin, and desmopressin.

Toxicity:
Lithium salts have a narrow therapeutic/toxic ratio. Risk factors for lithium toxicity include drugs altering renal function, decreased circulating volume, infections, fever, decreased oral intake of water, renal insufficiency, and nephrogenic diabetes insipidus. Features of lithium toxicity include GI symptoms and neuro symptoms.

Pre-prescribing:
Before prescribing lithium, renal function, cardiac function, thyroid function, FBC, and BMI should be checked. Women of childbearing age should be advised regarding contraception, and information about toxicity should be provided.

Monitoring:
Lithium blood levels should be checked weekly until stable, and then every 3-6 months once stable. Thyroid and renal function should be checked every 6 months. Patients should be issued with an information booklet, alert card, and record book.

Escape conditioning involves ending an unpleasant stimulus by performing a certain behavior, while avoidance conditioning involves avoiding the presentation of an unpleasant stimulus by performing a certain behavior.

Operant Conditioning: Reinforcement, Punishment, and More

Operant conditioning, also known as instrumental learning, is a theory of learning developed by B.F. Skinner. It suggests that people learn by interacting with their environment. Reinforcement and punishment are key concepts in operant conditioning. A reinforcer is a stimulus of event that increases the likelihood of a behavior being repeated. Reinforcement can be positive of negative. Positive reinforcement occurs when a behavior is strengthened by adding a rewarding stimulus, while negative reinforcement occurs when a behavior is strengthened by removing an unpleasant stimulus. A punisher is a stimulus that decreases the likelihood of a behavior being repeated. Positive punishment occurs when a behavior is reduced in frequency by adding an unpleasant stimulus, while negative punishment occurs when a behavior is reduced in frequency by removing a pleasant stimulus.

Primary reinforcers are instinctual desires such as food, water, social approval, and sex. Secondary reinforcers, also known as conditioned reinforcers, are not innately appreciated and people have to learn to like them through classical conditioning of other methods. Secondary reinforcers include things such as money. Different patterns of reinforcement have different influences on the response. There are five main reinforcement schedules: fixed interval, variable interval, fixed ratio, variable ratio, and random. Variable ratio schedules are most resistant to extinction.

Shaping and chaining are techniques used when an exact behavior cannot be performed and so cannot be rewarded. Shaping involves rewarding successive, increasingly accurate approximations to the behavior, while chaining involves breaking a complex task into smaller, more manageable sections. Escape conditioning refers to a situation whereby an aversive situation is removed after a response. It is a form of negative reinforcement. Habituation refers to the phenomenon whereby there is a decrease in response to a stimulus over time. Covert sensitization is a technique used whereby someone learns to use mental imagery to associate a behavior with a negative consequence.

Adregenic receptors are A1, A2, B1, B2, B3. Out of these, the function of the A2 receptor is inhibition of transmitter release including nor adrenalin and acetylcholine of the autonomic nervous system.

Anankastic personality disorder, previously known as obsessive-compulsive personality disorder in DSM-IV, is a condition where individuals are excessively focused on schedules, rules, and details. Their perfectionism can hinder their ability to meet the criteria outlined in ICD-10, which characterizes the disorder as one marked by doubt, excessive conscientiousness, preoccupation with details, checking, stubbornness, caution, and rigidity. People with this disorder may experience persistent and unwanted thoughts of impulses that do not reach the level of an obsessive-compulsive disorder. They may also struggle to function effectively at work due to difficulty completing tasks.

Piaget’s Stages of Development and Key Concepts

Piaget developed four stages of development that describe how children think and acquire knowledge. The first stage is the Sensorimotor stage, which occurs from birth to 18-24 months. In this stage, infants learn through sensory observation and gain control of their motor functions through activity, exploration, and manipulation of the environment.

The second stage is the Preoperational stage, which occurs from 2 to 7 years. During this stage, children use symbols and language more extensively, but they are unable to think logically of deductively. They also use a type of magical thinking and animistic thinking.

The third stage is the Concrete Operational stage, which occurs from 7 to 11 years. In this stage, egocentric thought is replaced by operational thought, which involves dealing with a wide array of information outside the child. Children in this stage begin to use limited logical thought and can serialise, order, and group things into classes on the basis of common characteristics.

The fourth and final stage is the Formal Operations stage, which occurs from 11 through the end of adolescence. This stage is characterized by the ability to think abstractly, to reason deductively, to define concepts, and also by the emergence of skills for dealing with permutations and combinations.

Piaget also developed key concepts, including schema, assimilation, and accommodation. A schema is a category of knowledge and the process of obtaining that knowledge. Assimilation is the process of taking new information into an existing schema, while accommodation involves altering a schema in view of additional information.

Overall, Piaget’s stages of development and key concepts provide a framework for understanding how children learn and acquire knowledge.

Heritability: Understanding the Concept

Heritability is a concept that is often misunderstood. It is not a measure of the extent to which genes cause a condition in an individual. Rather, it is the proportion of phenotypic variance attributable to genetic variance. In other words, it tells us how much of the variation in a condition seen in a population is due to genetic factors. Heritability is calculated using statistical techniques and can range from 0.0 to 1.0. For human behavior, most estimates of heritability fall in the moderate range of .30 to .60.

The quantity (1.0 – heritability) gives the environment ability of the trait. This is the proportion of phenotypic variance attributable to environmental variance. The following table provides estimates of heritability for major conditions:

Condition Heritability estimate (approx)
ADHD 85%
Autism 70%
Schizophrenia 55%
Bipolar 55%
Anorexia 35%
Alcohol dependence 35%
Major depression 30%
OCD 25%

It is important to note that heritability tells us nothing about individuals. It is a population-level measure that helps us understand the relative contributions of genetic and environmental factors to a particular condition.

Postural hypotension is a known side effect of alpha-1-blockade.

Antipsychotics: Common Side Effects and Relative Adverse Effects

Antipsychotics are medications used to treat various mental health conditions, including schizophrenia and bipolar disorder. However, they can also cause side effects that can be bothersome of even serious. The most common side effects of antipsychotics are listed in the table below, which includes the adverse effects associated with their receptor activity.

Antidopaminergic effects: These effects are related to the medication’s ability to block dopamine receptors in the brain. They can cause galactorrhoea, gynecomastia, menstrual disturbance, lowered sperm count, reduced libido, Parkinsonism, dystonia, akathisia, and tardive dyskinesia.

Anticholinergic effects: These effects are related to the medication’s ability to block acetylcholine receptors in the brain. They can cause dry mouth, blurred vision, urinary retention, and constipation.

Antiadrenergic effects: These effects are related to the medication’s ability to block adrenaline receptors in the body. They can cause postural hypotension and ejaculatory failure.

Histaminergic effects: These effects are related to the medication’s ability to block histamine receptors in the brain. They can cause drowsiness.

The Maudsley Guidelines provide a rough guide to the relative adverse effects of different antipsychotics. The table below summarizes their findings, with +++ indicating a high incidence of adverse effects, ++ indicating a moderate incidence, + indicating a low incidence, and – indicating a very low incidence.

Drug Sedation Weight gain Diabetes EPSE Anticholinergic Postural Hypotension Prolactin elevation
Amisulpride – + + + – – +++
Aripiprazole – +/- – +/- – – –
Asenapine + + +/- +/- – – +/-
Clozapine +++ +++ +++ – +++ +++ –
Flupentixol + ++ + ++ ++ + +++
Fluphenazine + + + +++ ++ + +++
Haloperidol + + +/- +++ + + +++
Olanzapine ++ +++ +++ +/- + + +
Paliperidone + ++ + + + ++ +++
Pimozide + + – + + + +++
Quetiapine ++ ++ ++ – + ++ –
Risperidone + ++ + + + ++ +++
Zuclopenthixol ++ ++ + ++ ++ + +++

Overall, it is important to discuss the potential side effects of antipsychotics with a healthcare provider and to monitor for any adverse effects while taking these medications.

Proprioception, also known as kinaesthesia, is the sense through which humans perceive their own position and movements. α nerve fibers are specifically involved in transmitting proprioception stimuli.

Extrapyramidal side-effects (EPSE’s) are a group of side effects that affect voluntary motor control, commonly seen in patients taking antipsychotic drugs. EPSE’s include dystonias, parkinsonism, akathisia, and tardive dyskinesia. They can be frightening and uncomfortable, leading to problems with non-compliance and can even be life-threatening in the case of laryngeal dystonia. EPSE’s are thought to be due to antagonism of dopaminergic D2 receptors in the basal ganglia. Symptoms generally occur within the first few days of treatment, with dystonias appearing quickly, within a few hours of administration of the first dose. Newer antipsychotics tend to produce less EPSE’s, with clozapine carrying the lowest risk and haloperidol carrying the highest risk. Akathisia is the most resistant EPSE to treat. EPSE’s can also occur when antipsychotics are discontinued (withdrawal dystonia).

While Mary Rothbart, Rudolf Steiner, and Jerome Kagan are known for their theories on the stability of personality traits in children, they were not involved in the New York Longitudinal Study conducted in the 1970s. However, Solomon Diamond, who focused on personality and temperament and conducted research on various animal studies, is also associated with this field.

The delusional psychopathology is a secondary factor that can lead to delusions, while the other examples are considered primary delusions. It’s important to note that delusional mood is distinct from the mood disorder associated with depression, as it refers to a subtle sense of paranoia of unusual feeling that may precede the development of delusional beliefs.

Borderline Learning Disability

Borderline learning disability is a term used to describe individuals with an IQ between 70-85. This category is not officially recognized as a diagnosis by the ICD-11. It is estimated that approximately 15% of the population falls within this range (Chaplin, 2005). Unlike mild learning disability, borderline learning disability is not typically associated with deficits in adaptive functioning, such as grooming, dressing, safety, of money management.

Brain Anatomy

The brain is a complex organ with various regions responsible for different functions. The major areas of the cerebrum (telencephalon) include the frontal lobe, parietal lobe, occipital lobe, temporal lobe, insula, corpus callosum, fornix, anterior commissure, and striatum. The cerebrum is responsible for complex learning, language acquisition, visual and auditory processing, memory, and emotion processing.

The diencephalon includes the thalamus, hypothalamus and pituitary, pineal gland, and mammillary body. The thalamus is a major relay point and processing center for all sensory impulses (excluding olfaction). The hypothalamus and pituitary are involved in homeostasis and hormone release. The pineal gland secretes melatonin to regulate circadian rhythms. The mammillary body is a relay point involved in memory.

The cerebellum is primarily concerned with movement and has two major hemispheres with an outer cortex made up of gray matter and an inner region of white matter. The cerebellum provides precise timing and appropriate patterns of skeletal muscle contraction for smooth, coordinated movements and agility needed for daily life.

The brainstem includes the substantia nigra, which is involved in controlling and regulating activities of the motor and premotor cortical areas for smooth voluntary movements, eye movement, reward seeking, the pleasurable effects of substance misuse, and learning.

Logistic regression is employed when dealing with dichotomous variables, which are variables that have only two possible values, such as live/dead of head/tail.

Stats: Correlation and Regression

Correlation and regression are related but not interchangeable terms. Correlation is used to test for association between variables, while regression is used to predict values of dependent variables from independent variables. Correlation can be linear, non-linear, of non-existent, and can be strong, moderate, of weak. The strength of a linear relationship is measured by the correlation coefficient, which can be positive of negative and ranges from very weak to very strong. However, the interpretation of a correlation coefficient depends on the context and purposes. Correlation can suggest association but cannot prove of disprove causation. Linear regression, on the other hand, can be used to predict how much one variable changes when a second variable is changed. Scatter graphs are used in correlation and regression analyses to visually determine if variables are associated and to detect outliers. When constructing a scatter graph, the dependent variable is typically placed on the vertical axis and the independent variable on the horizontal axis.

Alpha-Secretase: A Potential Treatment for Alzheimer’s Disease

Alpha-secretase is a promising avenue for preventing and treating Alzheimer’s disease. When amyloid precursor protein (APP) crosses the cell membrane, it can be cleaved by various enzymes. Alpha-secretase cleaves APP in a way that produces non-toxic protein fragments. However, beta and gamma-secretase are two other enzymes that can cleave APP, resulting in shorter, stickier fragments called beta-amyloid. These fragments can join together to form insoluble amyloid plaques. Researchers are developing drugs that can either stimulate alpha-secretase of block beta- and gamma-secretase, with the hope of preventing or treating Alzheimer’s disease.