Statins reduce our ability to make vital cholesterol. Cholesterol is used to make memory connections in the brain.  The linked paper is worrying for all statin users.

Synaptogenesis and neural cholesterol
Nowhere is the impact of cholesterol depletion more keenly studied than in the neurologic arena.  The work of Pfrieger et al. described the functional role of cholesterol in memory through synapto-genesis [24]. Mauch et al. [25] reported evidence that cholesterol is vital to the formation and correct operation of neurons to such an extent that neurons require additional sources of cholesterol to be secreted by glial cells. A recent mini-review by Jang et al. describes the synaptic vesicle secretion in neurons and its dependence upon cholesterol-rich membrane areas of the synaptic membrane [26]. Furthermore, working on rat brain synaptosomes, Waseem [23] demonstrated that a mere 9.3% decrease in the cholesterol level of the synaptosomal plasma membrane could inhibit exocytosis. These data might be particularly worrisome for lovastatin and simvastatin which are known to cross the blood brain barrier [27].
In fact, the proposed use of statins as a thera-peutic agent in Alzheimer’s disease (AD) [28] counters Pfrieger’s evidence [24]. Indeed, a reduc-tion in cholesterol synthesis leads to depletion of cholesterol in the lipid rafts – i.e. the de-novo cholesterol is required in the neurons for synaptic function and also in the neuronal membrane fusion pores [29].
Cognitive problems are the second most frequent type of adverse events, after muscle complaints, to be reported with statin therapy [30] and this has speculatively been attributed to mitochondrial effects. The central nervous sytem (CNS) cholesterol is synthesised in situ and CNS neurons only produce enough cholesterol to survive. The substantial amounts needed for synaptogenesis have to be supplemented by the glia cells. Having previously shown that in rat retinal ganglion cells without glia cells fewer and less efficient synapses could form, Göritz et al. [31] indicate that limiting cholesterol availability from glia directly affects the ability of CNS neurons to create synapses. They note that synthesis, uptake and transport of cholesterol directly impacts the development and plasticity of the synaptic circuitry. We note their very strong implication that local de-novo cholesterol synthesis in situ is essential in the creation and maintenance of memory.
There should be further consideration of cholesterol depletion on synaptogenesis, behaviours and memory loss for patients undergoing long-term statin therapy. This is particularly important with lipophilic statins which easily cross the blood brain barrier [32].
The effects of statins on cognitive function and the therapeutic potential of statins in Alzheimer’s disease are not clearly understood [28]. Two randomised trials of statins versus placebo in relatively younger healthier samples (lovastatin in one, simvastatin in other) showed significant worsening of cognitive indices relative to placebo [33, 34]. On the other hand, two trials in Alzheimer samples (with atorvastatin and simvastatin respectively) suggested possible trends to cognitive benefit, although these appeared to dissipate at 1 year [35, 36]. A recent Cochrane review concluded that there is good evidence from randomised trials that statins given in late life to individuals at risk of vascular disease have no effect in preventing Alzheimer´s disease or dementia [37]. However, case reports and case series from clinical practice in the real world reported cognitive loss on statins that resolved with discontinuation and recurred with rechallenge [30].

Statin Use Increases Dementia Risk