Other coincident diseases such as heart problems, diabetes, or history of alcohol abuse are also related with shortened survival. While the earlier the age at onset the higher the total survival years, life expectancy is particularly reduced when compared to the healthy population among those who are younger. Men have a less favourable survival prognosis than women.Pneumonia and dehydration are the most frequent immediate causes of death brought by Alzheimers disease, while cancer is a less frequent cause of death than in the general population. Epidemiology
Two main measures are used in epidemiological studies: incidence and prevalence. Incidence is the number of new cases per unit of person-time at risk (usually number of new cases per thousand person-years); while prevalence is the total number of cases of the disease in the population at any given time. Regarding incidence, cohort longitudinal studies (studies where a disease-free population is followed over the years) provide rates between 10 and 15 per thousand person-years for all dementias and 5–8 for Alzheimers disease, which means that half of new dementia cases each year are Alzheimers disease. Advancing age is a primary risk factor for the disease and incidence rates are not equal for all ages: every 5 years after the age of 65, the risk of acquiring the disease approximately doubles, increasing from 3 to as much as 69 per thousand person years. Females with Alzheimers disease are more common than males, but this difference is likely due to womens longer life spans.
Pseudohypoaldosteronism (PHA) is a condition that mimics hypoaldosteronism. However, the condition is due to a failure of response to aldosterone, and levels of aldosterone are actually elevated, due to a lack of feedback inhibition. Types
Presentation
PHA2 is clinically characterised by hypertension, hyperkalaemia, metabolic acidosis and normal renal function. Mechanism
PHA2 is also known as familial hyperkalaemic hypertension, or Gordon syndrome. The underlying genetic defect leads to increased sodium chloride reabsorption in the distal tubule in the kidney, leading to volume expansion, hypertension and lowered renin levels. The hyperkalemia found in PHA2 is proposed to be a function of diminished sodium delivery to the cortical collecting tubule (potassium excretion is mediated by the renal outer medullary potassium channel ROMK in which sodium reabsorption plays a role). Alternatively, WNK4 mutations that result in a gain of function of the Na-Cl co-transporter may inhibit ROMK activity resulting in hyperkalemia. Unlike in PHA1 in which aldosterone resistance is present, in PHA2 the volume expansion leads to relatively low aldosterone levels. Treatment
Treatment of severe forms of PHA1 requires relatively large amounts of sodium chloride. These conditions also involve hyperkalemia.In contrast, PHA2 (Gordons syndrome) requires salt restriction and use of thiazide diuretics to block sodium chloride reabsorption and normalise blood pressure and serum potassium. History
This syndrome was first described by Cheek and Perry in 1958.